GRB 230812B
GCN Circular 34386
Subject
GRB 230812B: Fermi GBM Final Real-time Localization
Date
2023-08-12T19:08:45Z (2 years ago)
From
Fermi GBM Team at MSFC/Fermi-GBM <do_not_reply@GIOC.nsstc.nasa.gov>
Via
email
The Fermi GBM team reports the detection of a likely LONG GRB
At 18:58:12 UT on 12 Aug 2023, the Fermi Gamma-ray Burst Monitor (GBM) triggered and located GRB 230812B (trigger 713559497.049606 / 230812790).
The on-ground calculated location, using the Fermi GBM trigger data, is RA = 250.1, Dec = 46.2 (J2000 degrees, equivalent to J2000 16h 40m, 46d 12'), with a statistical uncertainty of 1.0 degrees.
The angle from the Fermi LAT boresight is 29.0 degrees.
The skymap can be found here:
https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2023/bn230812790/quicklook/glg_skymap_all_bn230812790.png
The HEALPix FITS file, including the estimated localization systematic, can be found here:
https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2023/bn230812790/quicklook/glg_healpix_all_bn230812790.fit
The GBM light curve can be found here:
https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2023/bn230812790/quicklook/glg_lc_medres34_bn230812790.gif
GCN Circular 34387
Subject
GRB 230812B: Fermi GBM detection of an extremely bright GRB
Date
2023-08-12T19:51:19Z (2 years ago)
From
Stephen Lesage at Fermi-GBM Team <sjl0014@uah.edu>
Via
Web form
S. Lesage (UAH), E. Burns (LSU), S. Dalessi (UAH), and O. Roberts (USRA)
report on behalf of the Fermi GBM Team:
"At 18:58:12 UT on 12 August 2023, the Fermi Gamma-ray Burst Monitor (GBM)
triggered and located GRB 230812B (trigger 713559497/230812790).
The GBM light curve consists of an extremely bright short pulse, with the bulk of the emission during the first 2 seconds, and continued emission out to roughly 20 seconds. This event, if it is a GRB, it is extremely bright and follow-up across all wavelengths is encouraged.
The on-ground calculated location, using the Fermi GBM trigger data,
is RA = 250.06, Dec = 46.20 (J2000 degrees, equivalent to J2000 16h 40m, +46d 12'), with a statistical uncertainty of 1.00 degree
(radius, 1-sigma containment,
statistical only; there is additionally a systematic
error which we have characterized as a core-plus-tail model, with 90% of
GRBs having a 3.7 deg error and a small tail suffering a larger than 10 deg systematic error. [Connaughton et al. 2015, ApJS, 216, 32] ).
The angle from the Fermi LAT boresight is 29 degrees.
The skymap can be found here:
https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2023/bn230812790/quicklook/glg_skymap_all_bn230812790.png
The HEALPix FITS file, including the estimated localization systematic, can be found here:
https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2023/bn230812790/quicklook/glg_healpix_all_bn230812790.fit
The GBM light curve can be found here:
https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2023/bn230812790/quicklook/glg_lc_medres34_bn230812790.gif"
GCN Circular 34388
Subject
GRB 230812B: Tiled Swift observations
Date
2023-08-12T21:10:34Z (2 years ago)
From
Phil Evans at U of Leicester <pae9@star.le.ac.uk>
Via
email
P. A. Evans (U. Leicester) reports on behalf of the Swift team:
Swift has initiated a series of observations, tiled on the sky, of the
Fermi/GBM GRB 230812B. Automated analysis of the XRT data will
be presented online at http://www.swift.ac.uk/xrt_products/TILED_GRB00115
Any uncatalogued X-ray sources detected in this analysis will be
reported on this website and via GCN COUNTERPART notices. The probability of finding
serendipitous sources, unrelated to the Fermi/GBM event is high: any X-ray source
considered to be a probable afterglow candidate will be reported via a GCN Circular
after manual consideration.
Details of the XRT automated analysis methods are detailed in Evans et
al. (2007, A&A, 469, 379; 2009, MNRAS, 397, 1177 and 2014, ApJS, 210, 8).
This circular is an official product of the Swift-XRT team.
GCN Circular 34389
Subject
Fermi GRB 230812B: Global MASTER-Net observations report
Date
2023-08-12T22:31:08Z (2 years ago)
From
Vladimir Lipunov at Moscow State U/Krylov Obs <lipunov@xray.sai.msu.ru>
Via
legacy email
V. Lipunov, V.Kornilov, E.Gorbovskoy, K.Zhirkov, N.Tyurina, P.Balanutsa, A.Kuznetsov, D. Vlasenko,
G.Antipov, D.Zimnukhov, V.Senik, E.Minkina, A.Chasovnikov, V.Topolev, D.Kuvshinov, D.Cheryasov, Ya.Kechin
(Lomonosov Moscow State University, SAI, Physics Department),
R. Podesta, C.Lopez, F. Podesta, C.Francile
(Observatorio Astronomico Felix Aguilar OAFA),
R. Rebolo, M. Serra
(The Instituto de Astrofisica de Canarias),
D. Buckley
(South African Astronomical Observatory),
O.A. Gres, N.M. Budnev
(Irkutsk State University, API),
L.Carrasco, J.R.Valdes, V.Chavushyan, V.M.Patino Alvarez, J.Martinez, A.R.Corella, L.H.Rodriguez
(INAOE, Guillermo Haro Astrophysics Observatory),
A. Tlatov, D. Dormidontov
(Kislovodsk Solar Station of the Pulkovo Observatory),
A. Gabovich, V.Yurkov
(Blagoveschensk Educational State University)
MASTER-Tavrida robotic telescope (Global MASTER-Net: http://observ.pereplet.ru, Lipunov et al., 2010, Advances in Astronomy, vol. 2010, 30L) located in Russia (Lomonosov MSU, SAI Crimea astronomical station) started inspect of the Fermi GRB 230812B ( Fermi GBM team, GCN 34386) errorbox 10680 sec after notice time and 10713 sec after trigger time at 2023-08-12 21:56:45 UT, with upper limit up to 19.3 mag. The observations began at zenith distance = 50 deg. The sun altitude is -31.0 deg.
The galactic latitude b = 41 deg., longitude l = 72 deg.
Real time updated cover map and OT discovered available here:
https://master.sai.msu.ru/site/master2/observ.php?id=2253499
We obtain a following upper limits.
Tmid-T0 | Date Time | Site | Coord (J2000) |Filt.| Expt. | Limit| Comment
_________|_____________________|_____________________|____________________________________|_____|_______|_______|________
10804 | 2023-08-12 21:56:45 | MASTER-Tavrida | (16h 41m 41.24s , +46d 23m 36.1s) | C | 180 | 19.3 |
10992 | 2023-08-12 21:59:54 | MASTER-Tavrida | (16h 41m 46.04s , +46d 22m 29.1s) | C | 180 | 19.1 |
11111 | 2023-08-12 22:03:07 | MASTER-Tavrida | (16h 41m 40.73s , +46d 21m 24.6s) | C | 30 | 17.8 |
11151 | 2023-08-12 22:03:47 | MASTER-Tavrida | (16h 41m 47.62s , +46d 21m 41.9s) | C | 30 | 17.8 |
11189 | 2023-08-12 22:04:25 | MASTER-Tavrida | (16h 41m 44.53s , +46d 23m 10.6s) | C | 30 | 17.9 |
11227 | 2023-08-12 22:05:04 | MASTER-Tavrida | (16h 41m 44.48s , +46d 21m 32.8s) | C | 30 | 17.8 |
11267 | 2023-08-12 22:05:43 | MASTER-Tavrida | (16h 41m 47.52s , +46d 22m 59.5s) | C | 30 | 17.8 |
11304 | 2023-08-12 22:06:21 | MASTER-Tavrida | (16h 41m 40.68s , +46d 22m 18.0s) | C | 30 | 17.8 |
11343 | 2023-08-12 22:06:59 | MASTER-Tavrida | (16h 41m 41.50s , +46d 23m 16.6s) | C | 30 | 18.0 |
11381 | 2023-08-12 22:07:38 | MASTER-Tavrida | (16h 41m 47.28s , +46d 22m 15.3s) | C | 30 | 17.8 |
11495 | 2023-08-12 22:08:17 | MASTER-Tavrida | (16h 39m 42.09s , +46d 39m 09.7s) | C | 180 | 19.0 |
11683 | 2023-08-12 22:11:25 | MASTER-Tavrida | (16h 39m 49.58s , +46d 39m 04.4s) | C | 180 | 19.0 |
11874 | 2023-08-12 22:14:36 | MASTER-Tavrida | (16h 41m 28.89s , +45d 40m 34.6s) | C | 180 | 19.0 |
12063 | 2023-08-12 22:17:44 | MASTER-Tavrida | (16h 41m 29.14s , +45d 39m 21.9s) | C | 180 | 19.0 |
12251 | 2023-08-12 22:20:53 | MASTER-Tavrida | (16h 41m 31.63s , +45d 40m 21.9s) | C | 180 | 19.0 |
Filter C is a clear (unfiltred) band.
The observation and reduction will continue.
The message may be cited.
GCN Circular 34391
Subject
GRB 230812B: Fermi GBM Observation of a very bright burst
Date
2023-08-13T01:41:45Z (2 years ago)
From
Oliver J Roberts at USRA/NASA <oliver.roberts@nasa.gov>
Via
Web form
O.J. Roberts (USRA), C. Meegan (UAH), S. Lesage (UAH), E. Burns (LSU), and S. Dalessi (UAH)
report on behalf of the Fermi GBM Team:
"At 18:58:12.05 UT on 12 August 2023, the Fermi Gamma-Ray Burst Monitor (GBM)
triggered and located GRB 230812B (trigger 713559497 / 230812790). The Fermi
GBM Final Real-time Localization was previously reported (GBM team 2023, GCN 34386).
The angle from the Fermi LAT boresight at the GBM trigger time is 29 degrees.
The GBM light curve consists of a FRED-like burst with a duration (T90)
of about 3 s (10-1000 keV). The time-averaged spectrum over the whole burst
from T0-1s to T0+32 s is best fit by a Band function with Epeak = 273 +/- 3 keV,
alpha of -0.80 +/- 0.01 and beta of -2.47 +/-0.02.
The event fluence (10-1000 keV) in this time interval is
(2.5201 +/- 0.0002)E-04 erg/cm^2. The 1s peak photon flux measured
starting from T0+0.6 s in the 10-1000 keV band is 740 +/- 2 ph/s/cm^2.
Due to a timing glitch in the middle of the burst in the TTE data, this data
type had to be reprocessed and consequently, this preliminary report used the
CSPEC and CTIME data types only, which were unaffected. We note that due
to the intensity of the burst, pulse pile-up during the burst is highly likely.
This analysis is ongoing.
The spectral analysis results presented above are preliminary;
final results will be published in the GBM GRB Catalog:
https://heasarc.gsfc.nasa.gov/W3Browse/fermi/fermigbrst.html
For Fermi GBM data and info, please visit the official Fermi GBM Support Page:
https://fermi.gsfc.nasa.gov/ssc/data/access/gbm/"
GCN Circular 34392
Subject
GRB 230812B: Fermi-LAT detection
Date
2023-08-13T02:50:20Z (2 years ago)
From
Lorenzo Scotton at UAH <lscottongcn@outlook.com>
Via
Web form
L. Scotton (UAH), D. Kocevski (NASA/MSFC), J. Racusin (NASA/GSFC), and N. Omodei (Stanford University)
report on behalf of the Fermi-LAT Collaboration:
On August 12, 2023, Fermi-LAT detected high-energy emission from
GRB 230812B, which was also detected by Fermi-GBM (trigger 713559497/230812790, S. Lesage GCN 34387, O. Roberts GCN 34391).
The best LAT on-ground location is found to be
RA, Dec = 249.10, 47.75 (degrees, J2000)
with an error radius of 0.13 deg (90% containment, statistical error only).
This was 29 deg from the LAT boresight at the time of the GBM trigger:
T0 = 18:58:12.05 UT.
The data from the Fermi-LAT show a significant increase
in the event rate after the GBM trigger that is spatially correlated with the
GBM emission (1.69 degrees from the GBM location) with high significance.
The photon flux above 100 MeV in the time interval 0-50 s after the
GBM trigger is (1.96 +/- 0.27)E-4 ph/cm2/s.
The estimated photon index above 100 MeV is -2.16 +/- 0.14.
The highest-energy photon is a 72 GeV event which is observed 32.2 seconds
after the GBM trigger.
The Fermi-LAT point of contact for this burst is
Lorenzo Scotton (lorenzo.scotton AT uah.edu).
The Fermi-LAT is a pair conversion telescope designed to cover
the energy band from 20 MeV to greater than 300 GeV.
It is the product of an international collaboration between
NASA and DOE in the U.S. and many scientific institutions
across France, Italy, Japan and Sweden.
GCN Circular 34393
Subject
GRB 230812B: Preliminary Swift/XRT localization
Date
2023-08-13T04:03:06Z (2 years ago)
From
Jamie Kennea at Penn State U <jak51@psu.edu>
Via
Web form
J. A. Kennea (PSU) on behalf ot the Swift team,
In a target-of-opportunity observation taken starting 02:00UT on
August 13th, 2023, pointed at the LAT position (GCN 34392) of
GRB 230812B (GCN 34391), we find a previously uncatalogued X-ray
point source in preliminary data from Swift’s X-ray Telescope.
The preliminary position is RA/Dec (J2000) = 249.13957, 47.854760,
which is equivalent:
RA(J2000) = 16h 36m, 33.4s,
Dec(J2000) = +47d 51m 17.1s,
with an estimate error of 10 arcseconds radius. Please note this position
is based upon preliminary data, reported rapidly to aide follow-up. An
updated position will be reported via GCN ASAP.
GCN Circular 34394
Subject
GRB 230812B: Improved Swift/XRT localization
Date
2023-08-13T05:19:38Z (2 years ago)
From
K.L. Page at U Leicester <klp5@leicester.ac.uk>
Via
email
K.L. Page (U. Leicester) reports on behalf of the Swift-XRT team:
We have analysed 1.8 ks of XRT data for GRB 230812B, starting 25.4 ks
after the Fermi trigger (GCN 34391, 34392). The data are entirely in
Photon Counting (PC) mode. The currently best available XRT position is
RA, Dec = 249.1323, 47.8574, which is equivalent to:
RA (J2000): 16 36 31.76
Dec(J2000): +47 51 26.7
with an uncertainty of 3.7 arcsec (radius, 90% confidence).
We note that this is 20 arcsec from the preliminary position given in GCN
34393.
A detailed refined analysis circular will be sent when more data are
available.
This circular is an official product of the Swift-XRT team.
GCN Circular 34395
Subject
GRB 230812B: KAIT Optical Afterglow Candidate
Date
2023-08-13T05:26:37Z (2 years ago)
From
Weikang Zheng at UC Berkeley <weikang@berkeley.edu>
Via
legacy email
WeiKang Zheng and Alexei V. Filippenko (UC Berkeley) report on
behalf of the KAIT GRB team:
The 0.76-m Katzman Automatic Imaging Telescope (KAIT), located at
Lick Observatory, responded to GRB 230812B (The Fermi GBM team,
GCN 34386) starting at Aug. 13, 04:42:53 UT. We detected an uncataloged
optical afterglow candidate not shown in SDSS archive at position
of (error ~0.5"):
RA: 16:36:31.52 (J2000)
Dec: +47:51:32.24 (J2000)
This position is about 7.4 arcsec to the improved Swift/XRT
localization (Page et al., GCN 34393), which is slightly outside its
estimate 3.7 arcseconds error radius. We measure the target is
~18.7 in out clear band image at ~9.75 hours after burst. We can
not estimate the variability at this time, further observations
are encouraged.
GCN Circular 34396
Subject
Fermi GRB 230812B: MASTER optical counterpart
Date
2023-08-13T05:28:50Z (2 years ago)
From
Vladimir Lipunov at Moscow State U/Krylov Obs <lipunov@xray.sai.msu.ru>
Via
legacy email
V.Lipunov (Lomonosov MSU),
D.Svinkin (Ioffe Institute),
A.Kuznetsov, A.Sosnovskiy, N.Tiurina, E.Gorbovskoy, Ya.Kechin, P.Balanutsa, K.Zhirkov,
O.Gress, A.Chasovnikov, G.Antipov, D.Vlasenko, V.Senik, V.Topolev, Yu.Tselik, Siyu Wu, D.Cheryasov, V.Shumkov, T.Pogrosheva (Lomonosov Moscow State University,SAI,Physics Department),
C.Francile, F. Podesta, C.Lopez, R. Podesta (Observatorio Astronomico Felix Aguilar OAFA),
D.Buckley (SAAO),
R. Rebolo, M. Serra (The Instituto de Astrofisica de Canarias),
L.Carrasco, J.R.Valdes, V.Chavushyan, V.M.Patino
Alvarez,J.Martinez,A.Corella,L.H.Rodriguez (INAOE, Guillermo Haro Astrophysics Observatory),
N.M.Budnev, O.Gress (ISU,API),
A.Gabovich, V.Yurkov (BSPU),
A. Tlatov, D. Dormidontov (Kislovodsk Solar Station of the Pulkovo Observatory),
MASTER started Fermi GRB 230812B (Fermi GBM team GCN 34386, Ttrigger=18:58:12,
Lesage et al. GCN 34387, Evans et al. GCN 34388, Scotton et al. GCN 34387, Roberts et al. GCN 34391)
at MASTER-SAAO (Lipunov et al GCN 34389, see covermap, near horizont; GCN 34390) by MASTER-II and MASTER very wide field cameras (Lipunov et al. 2010)
Fermi GBM error-box was covered by MASTER-SAAO, MASTER-Tavrida (since 2023-08-12 21:56:45 UT), MASTER-OAFA.
There is optical counterpart at
R.A.,Dec.2000= 16 36 31.48 +47 51 35.14
with m=18.2 at several set of images.
that is in ~18" of Swift-XRT preliminary counterpart (Swift GCN 34393)
We observed it till sunrise in MASTER-Tavrida , reduction will be continued.
GCN Circular 34397
Subject
GRB 230812B: Zwicky Transient Facility Identifies Optical Afterglow Candidate of a Fermi GRB (Trigger 713559497)
Date
2023-08-13T08:02:28Z (2 years ago)
From
Anirudh Salgundi <salgundi.anirudh@gmail.com>
Via
Web form
Anirudh Salgundi (IITB), Vishwajeet Swain (IITB), Harsh Kumar (IITB), Tomas Ahumada (CIT), Robert Stein (CIT), Igor Andreoni (UMD), Michael Coughlin (UMN), Shreya Anand (CIT), Viraj Karambelkar (CIT), Mansi Kasliwal (CIT), Avery Wold (IPAC), Theophile du Laz (CIT), Simeon Reusch (DESY), Igor Andreoni (UMD), Eric Bellm (UW), Varun Bhalerao (IITB), Brad Cenko (UMD), Brian Healy (UMN), David Kaplan (UWM), Jannis Necker (DESY), D. Perley (LJMU) report on behalf of the ZTF and GROWTH collaborations:
We observed the localization region of the GRB 230812B (trigger 713559497, GCN 34386) detected by the Gamma-Ray Burst Monitor (GBM) on the Fermi satellite with the 47 square-degree Zwicky Transient Facility (ZTF) camera (Graham et al., 2019; Bellm et al., 2019). We obtained images in the g-, and r- covering 420 square degrees beginning at 2023-08-13 03:34:57 (~8.5 hours after the burst trigger time). This corresponds to ~78% of the probability enclosed in the Earth-occultation corrected GRB localization map. Each exposure was 300 seconds with median depths of 21.9 mag in both g-band and r-band. The images were processed in real-time through the ZTF reduction and image subtraction pipelines at IPAC (Masci et al. 2019).
We queried the ZTF alert stream using Kowalski (Duev et al. 2019) through Fritz (Coughlin et al. 2023). We required at least 2 detections separated by at least 15 minutes to select against moving objects. Furthermore, we cross-match our candidates with the Minor Planet Center to flag known asteroids, reject stellar sources (Tachibana and Miller 2018), and apply machine learning algorithms (Mahabal et al. 2019). We require that no spatially coincident ZTF alerts were issued before the detection time of the GBM trigger. Close to 40 sources were time and spatially coincident with the burst, most of them showing g-r ~ 0 mag and a slow evolution.
We recover the candidate afterglow reported in Zheng et al. (GCN 34395) and Lipunov et al. (GCN 34396), and we highlight its rapid evolution: r-band decay rate ~2 mag/day. We note that this source is ~6" from the source circulated in Page et al. (GCN 34394) detected by the Neil Gehrels Swift Observatory.
We additionally crossmatched the optical candidates to the Swift sources circulated and in Evans et al (GCN 34388, http://www.swift.ac.uk/xrt_products/TILED_GRB00115) and we find no other coincidences.
The details of the afterglow candidate in the table below:
ZTF name , AT name , UT first alert , t-t0 (days) , filter , mag (AB) , mag error (AB)
-----------------------------------------------------------------
ZTF23aaxeacr , AT 2023pel , 2023-08-13 03:34:56 , 0.35 , r , 18.85 , 0.04
ZTF23aaxeacr , AT 2023pel , 2023-08-13 04:24:05 , 0.39 , g , 19.19 , 0.02
We encourage further follow-up.
ZTF and GROWTH are worldwide collaborations comprising Caltech, USA; IPAC, USA, WIS, Israel; OKC, Sweden; JSI/UMd, USA; U Washington, USA; DESY,
Germany; MOST, Taiwan; UW Milwaukee, USA; LANL USA; Tokyo Tech, Japan; IITB, India; IIA, India; LJMU, UK; TTU, USA; SDSU, USA and USyd, Australia.
ZTF acknowledges the generous support of the NSF under AST MSIP Grant No 1440341.
GROWTH acknowledges generous support of the NSF under PIRE Grant No 1545949.
Alert distribution service provided by DIRAC@UW (Patterson et al. 2019).
Alert database searches are done by AMPEL (Nordin et al. 2019) and Kowalski (Duev et al. 2019). The GROWTH India Telescope (GIT; Kumar et al. 2022) is a 70-cm telescope with a 0.7-degree field of view, set up by the Indian Institute of Astrophysics (IIA) and the Indian Institute of Technology Bombay (IITB) with funding from DST-SERB and IUSSTF. It is located at the Indian Astronomical Observatory (Hanle), operated by IIA. We acknowledge funding by the IITB alumni batch of 1994, which partially supports the operations of the telescope. Telescope technical details are available at https://sites.google.com/view/growthindia/.
GCN Circular 34398
Subject
GOTO confirmation and possible host galaxy of GRB230812B optical afterglow
Date
2023-08-13T08:19:47Z (2 years ago)
From
ackleyastro@gmail.com
Via
Web form
K. Ackley; B. P. Gompertz; B. Godson; S. Belkin; D. O'Neill; A. Levan; T. Killestein; G. Ramsay; D. Malesani; R. Starling; M. J. Dyer; J. Lyman; K. Ulaczyk; F. Jiminez-Ibarra; A. Kumar; D. Steeghs; D. K. Galloway; V. Dhillon; P. O'Brien; K. Noysena; R. Kotak; R. P. Breton; L. K. Nuttall; E. Pall'e and D. Pollacco report on behalf of the GOTO collaboration:
We report on observations with the Gravitational-wave Optical Transient Observer (GOTO; Steeghs et al. 2022) in response to GRB 230812B (Page et al. GCN 34394, Scotton et al. GCN 34392, Lesage et al. GCN 34391). We covered the field of the X-ray (Swift, Page et al. GCN 34394) and optical (KAIT Zheng et al. GCN 34395, MASTER Lipunov et al. GCN 34396) candidate afterglow. The field was observed several times between 21:08:01 UT and 23:37:33 UT on 2023-08-12 (starting 2.16 hours after trigger). Each observation consisted of 4x90s exposures in the GOTO L-band (400-700 nm).
Images were processed immediately after acquisition using the GOTO pipeline. We confirm the optical afterglow as reported by KAIT (Zheng et al. GCN 34395) with the first detection at 2.29 hours. Our observations show a clear decay as the source faded by approximately 0.76 magnitudes over 2.27 hours.
Obs Date | RA(J2000) | Dec(J2000) | Filter | Mag(AB)
2023-08-12 21:15:40 | 249.13 | 47.86 | L | 17.45 +/- 0.02
We note the presence of an underlying extended source at the KAIT localisation in PS1 imaging and deep HyperSuprimeCam imaging, and suggest it to be the host galaxy of GRB 230812B.
Magnitudes were calibrated using ATLAS-REFCAT2 (Tonry et al. 2018) and are not corrected for Galactic extinction.
Observations are ongoing.
GOTO (https://goto-observatory.org) is a network of telescopes operated at the Roque de los Muchachos Observatory on La Palma, Spain, and Siding Spring Observatory in NSW, Australia, on behalf of a consortium including the University of Warwick, Monash University, Armagh Observatory & Planetarium, the University of Leicester, the University of Sheffield, the National Astronomical Research Institute of Thailand (NARIT), the University of Turku, the University of Portsmouth, the University of Manchester and the Instituto de Astrofisica de Canarias (IAC).
GCN Circular 34400
Subject
GRB 230812B: Swift-XRT afterglow detection
Date
2023-08-13T09:01:52Z (2 years ago)
From
Phil Evans at U of Leicester <pae9@star.le.ac.uk>
Via
legacy email
A.P. Beardmore (U. Leicester), A. Melandri (INAF-OAR), T. Sbarrato
(INAF-OAB), P. D'Avanzo (INAF-OAB), J.A. Kennea (PSU), A. Tohuvavohu
(U. Toronto), D.N. Burrows (PSU), J.P. Osborne (U. Leicester) and P.A.
Evans (U. Leicester) reports on behalf of the Swift-XRT team:
Swift-XRT has performed follow-up observations of the
Fermi/GBM-detected burst GRB 230812B in a series of observations tiled
on the sky. The total exposure time is 8.3 ks, distributed over 27
tiles; the maximum exposure at a single sky location was 4.6 ks. The
data were collected between T0+25.4 ks and T0+38.1 ks, and are entirely
in Photon Counting (PC) mode.
Four uncatalogued X-ray sources are detected, of which one ("Source 7")
is above the RASS 3-sigma upper limit at this position, and is
therefore likely the GRB afterglow. Using 4926 s of PC mode data and 4
UVOT images, we find an enhanced XRT position (using the XRT-UVOT
alignment and matching UVOT field sources to the USNO-B1 catalogue):
RA, Dec = 249.13196, +47.85892 which is equivalent to:
RA (J2000): 16h 36m 31.67s
Dec(J2000): +47d 51' 32.1"
with an uncertainty of 2.1 arcsec (radius, 90% confidence). This
position is 106.5 arcmin from the Fermi/GBM position, but only 6.7
arcmin from the Fermi/LAT position.
The light curve can be modelled with a power-law decay with a decay
index of alpha=1.8 (+/-0.4).
A spectrum formed from the PC mode data can be fitted with an absorbed
power-law with a photon spectral index of 1.82 (+/-0.15). The
best-fitting absorption column is 9.6 (+4.3, -3.9) x 10^20 cm^-2, in
excess of the Galactic value of 2.0 x 10^20 cm^-2 (Willingale et al.
2013). The counts to observed (unabsorbed) 0.3-10 keV flux conversion
factor deduced from this spectrum is 3.4 x 10^-11 (4.0 x 10^-11) erg
cm^-2 count^-1.
A summary of the PC-mode spectrum is thus:
Total column: 9.6 (+4.3, -3.9) x 10^20 cm^-2
Galactic foreground: 2.0 x 10^20 cm^-2
Excess significance: 3.2 sigma
Photon index: 1.82 (+/-0.15)
If the light curve continues to decay with a power-law decay index of
1.8, the count rate at T+24 hours will be 0.038 count s^-1,
corresponding to an observed (unabsorbed) 0.3-10 keV flux of 1.3 x
10^-12 (1.5 x 10^-12) erg cm^-2 s^-1.
The results of the XRT-team automatic analysis are available at
http://www.swift.ac.uk/xrt_products/00021589.
The results of the full analysis of the tiled XRT observations are
available at https://www.swift.ac.uk/xrt_products/TILED_GRB00115.
This circular is an official product of the Swift-XRT team.
GCN Circular 34401
Subject
GRB 230812B: GECAM-C observation of a very bright burst
Date
2023-08-13T09:31:23Z (2 years ago)
From
Dong Xu at NAOC/CAS <dxu@nao.cas.cn>
Via
email
Shaolin Xiong, Jiacong Liu, Yue Huang report on behalf of the GECAM team:
GECAM-C was triggered in-flight by a very bright burst, GRB 230812B, at 2023-08-12T18:58:12.100 UTC (T0), which was also observed by Fermi/GBM (Fermi GBM Team, GCN 34386), Fermi/LAT (Scotton et al, GCN 34392), etc. Both the GECAM-C in flight location and on-ground location are generally consistent with the Fermi/GBM within error.
According to the realtime alert data, the GECAM-C light curve shows a FRED shape with a duration (T90) of ~4 sec (6-1000 keV). The time-averaged spectrum shows that it could be adequately fit by a Band function with a fluence about 2E-4 erg/cm2 in 20-1000 keV. We note that this analysis is based on realtime alert data and thus very preliminary. Refined analysis will be reported later.
Gravitational wave high-energy Electromagnetic Counterpart All sky Monitor (GECAM) mission originally consists of two microsatellites (GECAM-A and GECAM-B) launched in Dec. 2020. As the third member of GECAM constellation, GECAM-C was launched onboard SATech-01 experimental satellite in July 2022. GECAM mission is funded by the Chinese Academy of Sciences (CAS).
GCN Circular 34402
Subject
GRB230812B: AGILE/MCAL detection
Date
2023-08-13T11:45:31Z (2 years ago)
From
Claudio Casentini at INAF-IAPS <claudio.casentini@inaf.it>
Via
Web form
C. Casentini (INAF/IAPS), F. Longo (Univ. Trieste and INFN Trieste), C. Pittori,
F. Verrecchia (SSDC, and INAF/OAR), M. Tavani (INAF/IAPS, and Univ. Roma Tor Vergata),
A. Ursi (ASI and INAF/IAPS), A. Argan, M. Cardillo, Y. Evangelista, L. Foffano,
G. Piano (INAF/IAPS), A. Addis, L. Baroncelli, A. Bulgarelli, A. Ciabattoni, A. Di Piano,
V. Fioretti, G. Panebianco, N. Parmiggiani (INAF/OAS-Bologna), F. Lucarelli
(SSDC, and INAF/OAR), M. Marisaldi (INAF/OAS-Bologna, and Bergen University), M. Pilia,
A. Trois (INAF/OA-Cagliari), I. Donnarumma, E. Menegoni (ASI), A. Giuliani (INAF/IASF-Mi),
P. W. Cattaneo (INFN Pavia), F. Cutrona (Univ. Milano Bicocca) and P. Tempesta
(TeleSpazio) report on behalf of the AGILE Team:
The AGILE satellite detected the GRB 230812B at T0 = 2023-08-12 18:58:12 s (UTC),
reported by Fermi (GCNs #34386, #34387, #34391, #34392), Swift (GCNs #34388, #34393,
#34394, #34395, #34399, #34400) and MASTER (GCNs #34389, #34396).
The event lasted about 8 s and it released a total number of 17046 counts in the MCAL
detector (above a background rate of 590 Hz) and 97310 counts in the AC-Top detector
(above a background rate of 3188 Hz). The AGILE ratemeters light curves can be found
at http://www.agilescienceapp.it/notices/GRB230812B_AGILE_RM_ND.png .
The event also triggered a high time resolution MCAL data acquisition,
from T0 s to T0+2 s (UTC), and released 12643 counts in the detector, above
a background rate of 561 Hz. The MCAL light curve can be found
at http://www.agilescienceapp.it/notices/GRB230812B_084865_618951492.000000.png .
At the T0, the event was 55 deg off-axis.
Additional analysis of AGILE data is in progress. Automatic MCAL GRB alert Notices
can be found at: https://gcn.gsfc.nasa.gov/agile_mcal.html
GCN Circular 34403
Subject
Konus-Wind detection of GRB 230812B
Date
2023-08-13T12:39:29Z (2 years ago)
From
Dmitry Frederiks at Ioffe Institute <fred@mail.ioffe.ru>
Via
legacy email
D. Frederiks, A.Lysenko, A. Ridnaia, D. Svinkin,
A. Tsvetkova, M. Ulanov, and T. Cline,
on behalf of the Konus-Wind team, report:
The long very bright GRB 230812B (Fermi GBM detection:
Lessage et al., GCN 34387; Roberts et al., GCN 34391;
Fermi LAT detection: Scotton et al., GCN 34392;
GECAM-C observation: Xiong et al., GCN 34401;
AGILE/MCAL detection: Casentini et al., GCN 34402)
triggered Konus-Wind (KW) at T0=68292.611 s UT (18:58:12.611).
The burst light curve shows a single smooth emission pulse,
which starts at ~T0-0.1 s, peaks at ~T0+0.7 s,
and has a total duration of ~20 s.
The emission is seen up to ~5 MeV.
The Konus-Wind light curve of this GRB is available at
http://www.ioffe.ru/LEA/GRBs/GRB230812_T68292/
As observed by Konus-Wind, the burst had
a fluence of (3.27 ± 0.07)x10^-4 erg/cm^2 and
a 64-ms peak energy flux, measured from T0 + 0.704 s,
of (2.63 ± 0.11)x10^-4 erg/cm^2/s (both in the 20 keV - 10 MeV energy range).
The time-integrated spectrum (measured from T0 to T0+19.712 s)
is best fit in the 20 keV - 15 MeV range
by a GRB (Band) function with the following model parameters:
the low-energy photon index alpha = -0.85 (-0.03,+0.03),
the high energy photon index beta = -2.38 (-0.05,+0.04),
the peak energy Ep = 288 (-12,+12) keV,
chi2 = 169/97 dof.
The spectrum near the peak count rate (measured from T0+0.512 to T0+0.768 s)
is best fit in the 20 keV - 15 MeV range
by a GRB (Band) function with the following model parameters:
the low-energy photon index alpha = -0.17 (-0.08,+0.09),
the high energy photon index beta = -2.65 (-0.14,+0.11),
the peak energy Ep = 444 (-30,+31) keV,
chi2 = 68/56 dof.
All the quoted errors are estimated at the 90% confidence level.
All the presented results are preliminary.
GCN Circular 34404
Subject
GRB 230812B: GMG - GRANDMA observations
Date
2023-08-13T14:40:05Z (2 years ago)
From
Jirong Mao at Yunnan Obs <jirongmao@mail.ynao.ac.cn>
Via
Web form
J. Mao, K.-X. Lu, J.-M. Bai (YNAO), S. Karpov (FZU), M. C. Coughlin (UMN), A. Ugarte Postigo, S. Antier (OCA), O. Pyhsna (Univ. KieV), Z. Vidadi (Shao) on behalf of the Yunnan observatories team and the GRANDMA team:
We observed the field of GRB 230812B (Lesage et al. GCN 34387; Scotton et al. GCN 34392; Page GCN 34394; Zheng & Filippenko GCN 34395; Lipunov et al. GCN 34396; Salgundi et al. GCN 34397; Ackley et al. GCN 34398; Xiong et al. GCN 34401; Casentini et al. 34002; Frederiks et al. 34404) by the GMG telescope in Yunnan observatories. The observation began from UT 13:34:22 August 13, 2023, about 18.5 hours from the trigger. We clearly observed the optical afterglow of R~19.9+/-0.1. The further observation is ongoing.
GCN Circular 34405
Subject
GRB 230812B: Detected Optical Afterglow Candidate
Date
2023-08-13T17:32:55Z (2 years ago)
From
Mohammad Odeh at Al Khatim Observatory M44 <mshodeh@gmail.com>
Via
legacy email
Mohammad Odeh, Osama Ghannam, Anas Mohammad, Khalfan Al-Noaimy, and Sameh
Al-Ashi, report on behalf of Al-Khatim Observatory (AKO) operated by the
International Astronomical Center in Abu Dhabi, UAE:
We observed the field of GRB 230812B (Lesage et al., GCN 34387; Scotton et
al., GCN 34392; Page, GCN 34394; Zheng & Filippenko, GCN 34395; Lipunov et
al., GCN 34396; Salgundi et al., GCN 34397; Ackley et al., GCN 34398; Xiong
et al., GCN 34401; Casentini et al., GCN 34002; Frederiks et al., GCN
34403; Mao et al., GCN 34404), with our 0.36m f/7.7 robotic telescope. The
observation was done on 13 August 2023 from 16:15 to 16:47 (UT), about 21.6
hours from the trigger.
We obtained multiple 180-sec exposures in Ic filter. We detected an optical
afterglow candidate at:
R.A. (J2000): 16:36:31.45
Dec. (J2000): +47:51:32.3
That is the same localization of (Zheng & Filippenko, GCN 34395), which is
about 5.5 arcsec from the improved Swift/XRT localization (Page, GCN 34394).
The following observation was calculated using Atlas catalogue as a
reference:
-----------------------------------------------------------------------------
ObsTime (mid), Exposure (sec), Filter, Mag
-----------------------------------------------------------------------------
2023-08-13T16:32:40Z, 10 x 180s (stacked), Ic, 18.8 +/- 0.21
-----------------------------------------------------------------------------
The magnitude is not corrected for galactic extinction.
GCN Circular 34406
Subject
GRB 230812B: SAO RAS optical observations
Date
2023-08-13T22:20:02Z (2 years ago)
From
Moskvitin Alexander at SAO RAS <mosk@sao.ru>
Via
legacy email
A. S. Moskvitin and O. I. Spiridonova (SAO RAS), report on behalf of
the GRB follow-up team.
We observed the field of GRB 230812B (Lesage et al., GCN 34387;
Scotton et al., GCN 34392; Page, GCN 34394; Zheng & Filippenko, GCN
34395; Lipunov et al., GCN 34396; Salgundi et al., GCN 34397; Ackley
et al., GCN 34398; Xiong et al., GCN 34401; Casentini et al., GCN
34002; Frederiks et al., GCN 34403; Mao et al., GCN 34404; Odeh et
al., GCN 34405) with the 1-m telescope of SAO RAS Zeiss-1000 equipped
with the CCD photometer. We obtained 3 x 300 sec. images in Rc band on
August 13, 20:14:15--20:31:46 UT under mediocre weather conditions.
The OT is clearly detected in our stacked frame with the brightness of
R = 20.45 +/- 0.07 (t_mid - t0 = 1.0589 days).
This preliminary photometry is based on the nearby SDSS stars;
magnitudes are converted using Lupton (2005) equations.
GCN Circular 34408
Subject
GRB 230812B: Montarrenti Observatory optical observations
Date
2023-08-14T00:58:33Z (2 years ago)
From
Simone Leonini at Montarrenti Observatory (Siena, Italy) <s.leonini@iol.it>
Via
Web form
S. Leonini, M. Conti, P. Rosi, L.M. Tinjaca Ramirez (Montarrenti Observatory, Siena, Italy) report:
We observed the field of GRB 230812B (Lesage et al., GCN 34387; Scotton et al., GCN 34392; Page, GCN 34394; Zheng & Filippenko, GCN 34395; Lipunov et al., GCN 34396; Salgundi et al., GCN 34397; Ackley et al., GCN 34398; Xiong et al., GCN 34401; Casentini et al., GCN 34002; Frederiks et al., GCN 34403; Mao et al., GCN 34404; Odeh et al., GCN 34405; Moskvitin et al., GCN 34406) with the automatic 0.53m Ritchey-Chretien telescope at Montarrenti Observatory (Siena, Italy, IAU code C88).
The observations were started under good weather conditions at 2023-08-13 19:20:53 UT (approximately 24 hours after burst) stacking 50x30s R and I-band CCD images.
The OT was clearly detected at the following position:
RA (J2000.0) 16h 36m 31.47s +/-0.11
Decl. (J2000.0) +47° 51' 32.7" +/-0.14
Preliminary photometry is obtained using nearby PanSTARRS stars as follows:
MJD Filter Mag. Err.
60170.32784 R 20.48 +/-0.07
60170.32827 I 19.78 +/-0.10
Magnitudes are converted using Lupton (2005) equations and are not corrected for galactic dust extinction.
GCN Circular 34409
Subject
GRB 230812B: Redshift from OSIRIS+/GTC
Date
2023-08-14T01:49:35Z (2 years ago)
From
Antonio de Ugarte Postigo at OCA <deugarte@oca.eu>
Via
email
A. de Ugarte Postigo (OCA-CNRS), J.F. Agui Fernandez (IAA-CSIC), C. C Thoene (ASU-CAS) and L. Izzo (INAF-OACN and DARK/NBI) report:
We have observed the afterglow of GRB 230812B (Roberts et al. GCN34391, Scotton et al. GCN 34392, Zheng & Filippenko GCN 34395, Beardmore et al. GCN 34400) with OSIRIS+ mounted on the 10.4m GTC telescope at Roque de los Muchachos Observatory in La Palma (Spain). The observation consisted of spectroscopy with an exposure time of 3x900s and grism R1000B, with a wavelength coverage between 3600 and 7800 AA. The first spectrum started at 21:37 UT, 1.110 days after the burst.
In a preliminary reduction using old calibrations, the spectrum shows a strong trace with both emission and absorption lines which we identify as MgII, MgI, CaII, CaI in absorption, and [OII] and [OIII] in emission, at a common redshift of 0.360, which we interpret as the redshift of the GRB.
At this redshift, and assuming a fluence of 3.27e-4 erg/cm^2 as reported by Fermi/GBM (Roberts et al. GCN34391), the burst would have an Eiso = 8.3e52 erg. Together with a Ep = 273 keV (Roberts et al. GCN34391), GRB 230812B is consistent with the Amati relation for long GRBs.
We acknowledge excellent support from the GTC staff.
GCN Circular 34410
Subject
GRB 230812B: Spectroscopy from NOT
Date
2023-08-14T01:51:16Z (2 years ago)
From
Antonio de Ugarte Postigo at OCA <deugarte@oca.eu>
Via
email
A. de Ugarte Postigo (OCA-CNRS), L. Izzo (INAF-OACN and DARK/NBI), D.B. Malesani (Radboud and DAWN/NBI), K. Matilainen (NOT) report:
We have observed the afterglow of GRB 230812B (Roberts et al. GCN34391, Scotton et al. GCN 34392, Zheng & Filippenko GCN 34395, Beardmore et al. GCN 34400) with AlFOSC, mounted on the 2.5m NOT telescope at Roque de los Muchachos Observatory in La Palma (Spain).
We have performed spectroscopy with an exposure of 3x1200s and grism #4, with a spectral coverage between 3500 and 9600 AA. The observation started at 22:14 UT, 1.136 days after the trigger.
The spectrum shows a trace throughout the complete spectral range. In a preliminary reduction we don’t identify clear absorption features, but we do see weak detections of [OII], [OIII] and H-alpha at a redshift of z=0.360, as reported by de Ugarte Postigo et al. (GCN34409).
GCN Circular 34412
Subject
GRB 230812B: AbAO optical observations
Date
2023-08-14T08:02:51Z (2 years ago)
From
Alexei Pozanenko at IKI, Moscow <apozanen@iki.rssi.ru>
Via
legacy email
S. Belkin (IKI), R. Ya. Inasaridze (AbAO), A. Pozanenko (IKI), N.
Pankov (HSE, IKI) report on behalf of GRB IKI FuN:
We observed the field of GRB 230812B (Fermi GBM Team, GCN 34386; Scotton et al., GCN 34392; Page et al. GCN 34394; Kuin et al., GCN 34399; Casentini et al., GCN 34402) with AS-32 telescope of Abastumani observatory (AbAO) in R-filter starting on Aug. 13 (UT) 17:32:00. We detected the afterglow (Lesage et al., GCN 34387; Scotton et al., GCN 34392; Page, GCN 34394; Zheng & Filippenko, GCN 34395; Lipunov et al., GCN 34396; Salgundi et al., GCN 34397; Ackley et al., GCN 34398; Xiong et al., GCN 34401; Casentini et al., GCN 34402; Frederiks et al., GCN 34403; Mao et al., GCN 34404; Odeh et al., GCN 34405; Moskvitin et al., GCN 34406; Leonini et al., GCN 34408; de Ugarte Postigo et al., GCNs 24409, 34410) in the stacked image. Preliminary photometry of the object is following
Date UT start t-T0 Filter Exp. OT Err. UL(3sigma)
(mid, days) (s)
2023-08-13 17:32:00 0.97336 R 54*60 20.35 0.24 20.9
The photometry is based on nearby SDSS stars used in (Moskvitin et al, GCN 34406):
RA DEC R (Lupton transformations)
16:36:35.9365104 +47:52:54.574320 14.893 0.008
16:36:32.6835360 +47:53:44.537784 16.531 0.009
16:36:25.6055880 +47:53:20.456304 16.827 0.009
16:36:25.1691816 +47:52:20.931816 16.068 0.008
16:36:44.6580984 +47:50:56.806944 15.785 0.008
16:36:40.1374488 +47:54:02.128752 15.698 0.008
The underlying extended source galaxy mentioned by GOTO (Ackley et al., GCN 34398) is visible in Legacy Survey DR10 Catalog with r~22.66 and classified as round exponential galaxy.
GCN Circular 34413
Subject
GRB 230812B: OASDG optical observations
Date
2023-08-14T10:47:40Z (2 years ago)
From
luca.izzo@inaf.it
Via
Web form
N. Ruocco, A. Catapano (OASDG) and L. Izzo (INAF-OACN & DARK/NBI) report:
We observed the field of GRB 230812B (Lesage et al. GCN 34387, Roberts et al. GCN 34391, Scotton et al. GCN 34392, Beardmore et al. GCN 34400, Xiong et al. GCN 34401, Casentini et al. GCN 34402, Frederiks et al. GCN 34403) with the 0.5m telescope of the Osservatorio Astronomico S. Di Giacomo located in Agerola, Italy ( https://osservatorio.astrocampania.it/ - MPC L07). We obtained multiple 300s images in the Rc filter under good weather conditions, with the first observation starting at MJD 60169.818 (1.027 days after the GRB detection).
In the final stacked image, we detect a faint source at the enhanced position reported by Swift-XRT (Beardmore et al. GCN 34400) and by optical telescopes (Zheng & Filippenko, GCN 34395, Lipunov et al., GCN 34396, Salgundi et al., GCN 34397, Ackley et al., GCN 34398, Kuin et al. GCN 34399, Mao et al., GCN 34404, Odeh et al., GCN 34405, Moskvitin et al., GCN 34406, Leonini et al., GCN 34408, de Ugarte Postigo et al. GCN 34409 & 34410, Belkin et al., GCN 34412). We measure a magnitude for the GRB afterglow of Rc(AB) = 20.51 +/- 0.16 mag. The calibration was performed using nearby stars in the Pan-STARRS PS1 catalog, and using transformation equations to Rc magnitudes. Further analyses are ongoing.
GCN Circular 34414
Subject
GRB 230812B: rest-frame energetics from Konus-Wind observation
Date
2023-08-14T13:26:42Z (2 years ago)
From
Dmitry Frederiks at Ioffe Institute <fred@mail.ioffe.ru>
Via
legacy email
D. Frederiks, A.Lysenko, A. Ridnaia, D. Svinkin,
A. Tsvetkova, M. Ulanov, and T. Cline,
on behalf of the Konus-Wind team, report:
Assuming the spectrum and the observer-frame energetics of the very bright
GRB 230812B measured by KW (GCN 34403); the source redshift z=0.360
(de Ugarte Postigo et al., GCNs 34409, 34410); and a standard cosmology
with H_0 = 67.3 km/s/Mpc, Omega_M = 0.315, and Omega_Lambda = 0.685 (Planck Collaboration, 2014);
we estimate the burst isotropic energy release E_iso to (1.09 ± 0.02)x10^53 erg,
the isotropic peak luminosity L_iso to (1.25 ± 0.05)x10^53 erg/s,
the rest-frame peak energy of the time-integrated spectrum Ep,i,z to (392 ± 16) keV,
and the rest-frame peak energy at the peak of the emission Ep,p,z to (604 ± 41) keV.
With the obtained estimates, GRB 220627A fits perfectly both 'Amati' and 'Yonetoku'
relations derived for the sample of >300 long KW GRBs with known redshifts
(Tsvetkova et al., 2017; Tsvetkova et al., 2021), see
http://www.ioffe.ru/LEA/GRBs/GRB230812_T68292/GRB230812B_rest_frame.pdf
This suggests that an energy reservoir powering the burst and its emission mechanism
are similar to that typical of long-duration GRBs.
All the quoted errors are estimated at the 90% confidence level.
All the presented results are preliminary.
GCN Circular 34415
Subject
GRB 230812B: Osservatorio Astronomico "Nastro Verde" optical observation
Date
2023-08-14T13:45:40Z (2 years ago)
From
Nello Ruocco at Osservatorio Nastro Verde - Sorrento (Naples) - Italy - MPC Code C82 <osservatorionastroverde@gmail.com>
Via
Web form
Nello Ruocco at Osservatorio Nastro Verde - Sorrento (Naples) - Italy
in a large collaboration with:
M.G. Dainotti (National Astronomical Observatory of Japan),
Y. Niino (Tokyo University, Institute of Astronomy),
K. Kalinowski (Aarhus University, Department of Physics and Astronomy),
B. De Simone (Universita' degli Studi Di Salerno)
report:
We observed the field of GRB 230812B (Lesage et al. GCN 34387, Roberts et al. GCN 34391, Scotton et al. GCN 34392, Beardmore et al. GCN 34400, Xiong et al. GCN 34401, Casentini et al. GCN 34402, Frederiks et al. GCN 34403)
with telescope of Nastro Verde Observatory - Sorrento (Naples), Italy.
Member of:
AAVSO - American Association of Variable Star Observers.
UAI/SSV - Unione Astrofili Italiani/sezione stelle variabili.
AstroCampania Associazione
The observations started at 19:40 UT of 2023/08/13, after about 24 hours after the GRB trigger, at the end of twilight with clear skies, with principal telescope SC 0.35 f/10 with focal reduced + CCD Sbig ST10 XME
I took 22 image of 240 sec each. All images are unfiltered, calibrated with masterdark and masterflat, stacked with Tycho Tracker and Astrometrica software
We have detected a clearly visible source at the enhanced position reported by Swift-XRT (Beardmore et al. GCN 34400) and by optical telescopes (Zheng & Filippenko, GCN 34395, Lipunov et al., GCN 34396, Salgundi et al., GCN 34397, Ackley et al., GCN 34398, Kuin et al. GCN 34399, Mao et al., GCN 34404, Odeh et al., GCN 34405, Moskvitin et al., GCN 34406, Leonini et al., GCN 34408, de Ugarte Postigo et al. GCN 34409 & 34410, Belkin et al., GCN 34412, Ruocco et al. GCN 34413)
at following position
RA (J2000.0) 16h 36m 31.47s
Decl. (J2000.0) +47° 51' 32.2"
Preliminary photometry summing three sets of 7 images of 240 sec each, using Astrometrica and the UCAC4 catalog is as follows
2023 08 13.83014 16 36 31.46 +47 51 32.7 19.8 R
2023 08 13.85209 16 36 31.52 +47 51 32.1 19.8 R
2023 08 13.87403 16 36 31.47 +47 51 32.3 20.2 R
Magnitudes were estimated with the UCAC4 cat. and
are not corrected for galactic dust extinction.
The message may be cited.
GCN Circular 34416
Subject
GRB 230812B: Faulkes Telescope North optical afterglow follow-up
Date
2023-08-14T14:17:45Z (2 years ago)
From
Manisha Shrestha at University of Arizona <mshrestha1@arizona.edu>
Via
Web form
M. Shrestha (Univ. of Arizona), D. Sand (Univ. of Arizona), K. D. Alexander (Univ. of Arizona), J. Andrews (Gemini), K. Bostroem (Univ. of Arizona), J. Pearson (Univ. of Arizona), G. Hosseinzadeh (Univ. of Arizona), N. Smith (Univ. of Arizona), D. A. Howell (LCO/UCSB), C. McCully (LCO/UCSB), M. Newsome (LCO/UCSB), E Padilla Gonzalez (LCO/UCSB), C. Pellegrino (LCO/UCSB), G. Terreran (LCO/UCSB), J. Farah (LCO/UCSB) report on behalf of a wider Global Supernova Project collaboration:
We observed the field of Swift GRB 230812B (Fermi GBM GCN 34386) with Faulkes Telescope North, on 2023-08-14 at 5:50:39 UT (60170.2435 MJD, ~1.45 days after the trigger) using the MuSCAT3 imager in the g,r, and i bands. Data were calibrated with respect to nearby SDSS sources.
We clearly detect the optical counterpart in the g,r, and i bands. The magnitudes are as follows:
g = 21.38 +- 0.07
r = 20.81 +- 0.04
i = 20.71 +- 0.07
These values are not corrected for galactic extinction.
GCN Circular 34417
Subject
GRB 230812B: Bassano Bresciano Observatory optical observations
Date
2023-08-14T14:26:48Z (2 years ago)
From
Ulisse Quadri at Bassano Bresciano Obs <oabb@ulisse.bs.it>
Via
legacy email
U.Quadri and L.Strabla (Bassano Bresciano Astronomical Observatory),
in a large collaboration with:
M.G. Dainotti (National Astronomical Observatory of Japan),
Y. Niino (Tokyo University, Institute of Astronomy),
K. Kalinowski (Aarhus University, Department of Physics and Astronomy),
B. De Simone (Universita' degli Studi Di Salerno)
report:
We imaged the field of GRB 230812B (Lesage et al., GCN 34387;
Scotton et al., GCN 34392; Page, GCN 34394; Zheng & Filippenko, GCN 34395;
Lipunov et al., GCN 34396; Salgundi et al., GCN 34397; Ackley et al., GCN 34398;
Xiong et al., GCN 34401; Casentini et al., GCN 34002; Frederiks et al., GCN 34403;
Mao et al., GCN 34404; Odeh et al., GCN 34405; Moskvitin et al., GCN 34406)
detected by FERMI(trigger 713559497.049606 / 230812790)
with the robotic telescope of (IAU station 565) Bassano Bresciano
Observatory, Italy. Member of:
AAVSO - American Association of Variable Star Observers.
UAI/SSV - Unione Astrofili Italiani/sezione stelle variabili-GRB.
GAC - Gruppo Astrofili Cremonesi.
The observations started 24.57 hour after the FERMI trigger, At the end of twilight
with our Newton telescope D=250 mm F/D=4.8
Weather conditions were good.
We co-added 2 series of 70 exposures of 60 sec each.
Start T0+ End T0+
24.57 hour 27.09 hour
We detected a (fading) afterglow in the error box of the XRTcandidate.
at the following position (+/- 2 arcsec):
RA (J2000.0) = 16h 36m 31.51s
DEC(J2000.0) = +47d 51p 32.2s
The results of our photometry are:
-----------------------------------
JD Mag Err Flt
-----------------------------------
2460170.36459 19.9 +/- 0.2 CR
2460170.38708 20.1 +/- 0.2 CR
CR is unfiltered with R zero point.
Magnitudes were estimated with the PanSTARRS cat. and
are not corrected for galactic dust extinction.
Reference:
http://www.osservatoriobassano.org/GRB.asp
The message may be cited.
GCN Circular 34418
Subject
GRB 230812B : optical observations from Observatoire de Haute-Provence
Date
2023-08-14T15:16:09Z (2 years ago)
From
Emeric Le Floc'h at CEA-Saclay <emeric.lefloch@cea.fr>
Via
Web form
C. Adami (LAM), T. Adami (ENS Paris-Saclay), B. Schneider (MIT), A. Saccardi (GEPI, Obs. de Paris), A. de Ugarte Postigo (OCA, CNRS), E. Le Floc’h, F. Schüssler, D. Turpin (CEA-Saclay), S. D. Vergani, J. P. Palmerio (GEPI, Obs. de Paris), S. Basa (LAM), D. Götz (CEA-Saclay), S. Antier (OCA) report, on behalf of a larger collaboration:
We observed the field of GRB 230812B (Fermi GBM Team GCN, 34386; Roberts et al., GCN 34391; Scotton et al., GCN 34392; Page et al., GCN 34394; Zheng & Filippenko, GCN 34395; Kuin et al., GCN 34399; Beardmore et al., GCN 34400; Casentini et al., GCN 34402; de Ugarte Postigo et al., GCN 24409, 34410) using the T120 telescope of Observatoire de Haute Provence (OHP) in imaging mode. We obtained 10x360s exposures in the V-band with a mid-epoch of 2023-08-13 22:00 UT (~1 day after trigger), 2x300s exposures in the R-band with a mid-epoch of 2023-08-14 00:00 UT, and 10x360s exposures in the I band with a mid-epoch of 2023-08-13 20:40 UT.
We derive the following photometry, calibrated against the Pan-STARRS catalog and not corrected for Galactic dust reddening:
V = 20.87 +/- 0.08 mag
R = 20.64 +/- 0.09 mag
I = 19.77 +/- 0.04 mag
We also observed the field of GRB 230812B using the T193cm equipped with the MISTRAL spectro-imager. We obtained 4x300s + 1x60s exposures in the r’ band at a mid-epoch of 2023-08-13 20:15 UT, leading to the following preliminary photometry estimate:
r’ = 20.32 +/- 0.06 mag
We finally obtained 1h of exposure (2x15min + 1x30min) in spectroscopic mode, using the blue setting of MISTRAL. We clearly detect the continuum associated with the transient emission, leading to a redshift upper limit (z<2.5) consistent with the redshift determination obtained by the GTC and the NOT (de Ugarte Postigo et al., GCN 24409, 34410). The signal to noise in the final combined spectrum is however not sufficient to securely identify any absorption line.
We acknowledge Claire Moutou as well as the excellent support from Jean Balcaen and Yoann Degot-Longhi (Observatoire de Haute Provence).
GCN Circular 34419
Subject
GRB 230812B: Leavitt Observatory optical observations
Date
2023-08-14T16:37:57Z (2 years ago)
From
leavittob@gmail.com
Via
Web form
L. Moretti and E. Pavoni (Leavitt Observatory), in a large collaboration with:
M.G. Dainotti (National Astronomical Observatory of Japan),
Y. Niino (Tokyo University, Institute of Astronomy),
K. Kalinowski (Aarhus University, Department of Physics and Astronomy),
B. De Simone (Università degli Studi Di Salerno)
report:
We observed the field of GRB 230812B (Fermi GBM Team GCN, 34386; Roberts et al., GCN 34391; Scotton et al., GCN 34392; Page et al., GCN 34394; Zheng & Filippenko, GCN 34395; Kuin et al., GCN 34399; Beardmore et al., GCN 34400; Casentini et al., GCN 34402; de Ugarte Postigo et al., GCN 34409, 34410) with the telescope of Leavitt Observatory, Italy. Member of:
UAI/SSV - Unione Astrofili Italiani/sezione stelle variabili, GRB section.
ATA - Associazione Tuscolana di Astronomia.
The observations began at 20:35 UT on 2023/08/13 (~1 day after the FERMI trigger), at the end of twilight, with our RC telescope D=250 mm F/D=8.
Weather conditions were good.
We took 9 images of 240 sec each. All images are unfiltered, calibrated with master dark and master flat, stacked with ASTAP software.
We detected the afterglow at the following position:
RA(J2000) = 16h 36m 31.48s
Dec(J2000) = +47° 51' 32.1"
We measured its brightness of 20.78 +/- 0.2 mag in our coadd image in clear band, at a mid-time of 25.913 hours after the FERMI trigger, JD 2460170.36944.
Magnitudes were estimated with the Gaia (BP) DR3 cat. and are not corrected for galactic dust extinction.
The message may be cited.
GCN Circular 34420
Subject
GRB 230812B: GIT optical follow-up
Date
2023-08-14T18:22:14Z (2 years ago)
From
Vishwajeet Swain at IIT Bombay <vishwajeet.s@iitb.ac.in>
Via
Web form
R. Kumar (IITB), A. Salgundi (IITB), V. Swain (IITB), H. Kumar (IITB), V. Bhalerao (IITB), G.C. Anupama (IIA), S. Barway (IIA) and K. Angail (IAO) report on behalf of the GIT team:
We observed the field of the GRB230812B (Fermi GBM Team, GCN 34386) with 0.7m GROWTH-India Telescope (GIT). We started the observation from 14:46:44 UT on 2023-08-13, roughly 20 hours after the Fermi trigger. We obtained multiple frames of 300 sec each in the g' and r' bands. We detected the afterglow in our stacked images at the enhanced Swift XRT localization (Beardmore et al. GCN 34400). The details of the photometry are given in the below table:
----------------------------------------------------------------------
JD (mid) | t-t0 (days)| Filter | Exposure (s) | Magnitude (AB) |
----------------------------------------------------------------------
2460170.139773 | 0.85 | g' | 5 x 300 | 20.34 +/- 0.06 |
2460170.121745 | 0.83 | r' | 4 x 300 | 19.98 +/- 0.05 |
----------------------------------------------------------------------
Our photometry values are consistent with the results submitted by other optical telescopes (Zheng & Filippenko, GCN 34395, Lipunov et al., GCN 34396, Salgundi et al., GCN 34397, Ackley et al., GCN 34398, Kuin et al. GCN 34399, Mao et al., GCN 34404, Odeh et al., GCN 34405, Moskvitin et al., GCN 34406, Leonini et al., GCN 34408, de Ugarte Postigo et al. GCN 34409 & 34410, Belkin et al., GCN 34412, and N. Ruocco et al., GCN 34413, N. Ruocco et al., GCN 34413, M. Shrestha et al., GCN 34416, C. Adami et al., GCN 34418, L. Moretti et al., GCN 34419).
We confirm that the candidate is decaying fast.
The GROWTH India Telescope (GIT; Kumar et al. 2022) is a 70-cm telescope with a 0.7-degree field of view, set up by the Indian Institute of Astrophysics (IIA) and the Indian Institute of Technology Bombay (IITB) with funding from DST-SERB and IUSSTF. It is located at the Indian Astronomical Observatory (Hanle), operated by IIA. We acknowledge funding by the IITB alumni batch of 1994, which partially supports the operations of the telescope. Telescope technical details are available at https://sites.google.com/view/growthindia/.
GCN Circular 34421
Subject
GRB 230812B: Koshka Zeiss-1000 optical observations
Date
2023-08-14T18:43:43Z (2 years ago)
From
Alexei Pozanenko at IKI, Moscow <apozanen@iki.rssi.ru>
Via
legacy email
S. Belkin (IKI), I. Nikolenko (INASAN), N. Pankov (HSE, IKI), A. Pozanenko (IKI) report on behalf of GRB IKI FuN:
We observed the field of GRB 230812B (Fermi GBM Team, GCN 34386; Scotton et al., GCN 34392; Page et al. GCN 34394; Kuin et al., GCN 34399; Casentini et al., GCN 34402) with Zeiss-1000 telescope of Koshka observatory in R-filter. We detected the afterglow (e.g. Lesage et al., GCN 34387; Scotton et al., GCN 34392; Page, GCN 34394; Zheng & Filippenko, GCN 34395; Lipunov et al., GCN 34396; Salgundi et al., GCN 34397; Ackley et al., GCN 34398; Xiong et al., GCN 34401; Casentini et al., GCN 34402; Frederiks et al., GCN 34403; Mao et al., GCN 34404; Odeh et al., GCN 34405; Moskvitin et al., GCN 34406; Leonini et al., GCN 34408; de Ugarte Postigo et al., GCNs 24409, 34410; Belkin et al., GCN 34412) in a stacked image. Preliminary photometry of the object is following
Date UT start t-T0 Filter Exp. OT Err. UL(3sigma) Telescope
(mid, days) (s)
2023-08-13 18:07:14 0.99724 R 35*120 20.18 0.07 22.0 Zeiss-1000
The photometry is based on nearby SDSS stars used in (Moskvitin et al, GCN 34406):
RA DEC R (Lupton transformations)
16:36:35.9365104 +47:52:54.574320 14.893 0.008
16:36:32.6835360 +47:53:44.537784 16.531 0.009
16:36:25.6055880 +47:53:20.456304 16.827 0.009
16:36:25.1691816 +47:52:20.931816 16.068 0.008
16:36:44.6580984 +47:50:56.806944 15.785 0.008
16:36:40.1374488 +47:54:02.128752 15.698 0.008
GCN Circular 34423
Subject
GRB 230812B: CrAO ZTSh optical observations
Date
2023-08-14T19:08:13Z (2 years ago)
From
Alexei Pozanenko at IKI, Moscow <apozanen@iki.rssi.ru>
Via
legacy email
S. Belkin (IKI), V. Rumyantsev (CrAO), N. Pankov (HSE, IKI), A. Pozanenko (IKI) report on behalf of GRB IKI FuN:
We observed the field of GRB 230812B (Fermi GBM Team, GCN 34386; Scotton et al., GCN 34392; Page et al. GCN 34394; Kuin et al., GCN 34399; Casentini et al., GCN 34402; Frederiks et al., GCN 34403) with ZTSH 2.6m telescope of CrAO observatory in R-filter. We detected the afterglow (e.g. Lesage et al., GCN 34387; Scotton et al., GCN 34392; Page, GCN 34394; Zheng & Filippenko, GCN 34395; Lipunov et al., GCN 34396; Salgundi et al., GCN 34397; Ackley et al., GCN 34398; Xiong et al., GCN 34401; Casentini et al., GCN 34402; Mao et al., GCN 34404; Odeh et al., GCN 34405; Moskvitin et al., GCN 34406; Leonini et al., GCN 34408; de Ugarte Postigo et al., GCNs 24409, 34410; Belkin et al., GCN 34412, 34421) in a stacked image. Preliminary photometry of the object is following
Date UT start t-T0 Filter Exp. OT Err. UL(3sigma)
(mid, days) (s)
2023-08-13 19:24:53 1.03829 R 39*120 20.25 0.05 23.3
The photometry is based on nearby SDSS stars used in (Moskvitin et al, GCN 34406):
RA DEC R (Lupton transformations)
16:36:35.9365104 +47:52:54.574320 14.893 0.008
16:36:32.6835360 +47:53:44.537784 16.531 0.009
16:36:25.6055880 +47:53:20.456304 16.827 0.009
16:36:25.1691816 +47:52:20.931816 16.068 0.008
16:36:44.6580984 +47:50:56.806944 15.785 0.008
16:36:40.1374488 +47:54:02.128752 15.698 0.008
GCN Circular 34425
Subject
GRB 230812B: GRANDMA further observations of ZTF23aaxeacr candidate afterglow
Date
2023-08-14T21:28:38Z (2 years ago)
From
Aleksandra Pyshna at Astronomical Observatory of Taras Shevchenko National University of Kyiv, Kyiv, Ukraine <pyshnaya.sasha@gmail.com>
Via
Web form
O. Pyshna (AO TSNU of Kyiv), Z. Vidadi (ShAO), S. Beradze (AbAO), Y.Rajabov (UBAI), D. Aql (American Uni. SHJ), S. Antier (OCA), M. Coughlin (UMN), J. Peloton, P. Hello (IJCLAB), S. Karpov, M. Prouza, M. Mašek, M. Blazek (FZU), A. Klotz (IRAP),T. Pradier (Univ. Strasbourg), I. Tosta e Melo (UNICT), D. Turpin (CEA), A. Takey, E. G. Elhosseiny, A. Abulwfa, M. A. El-Sadek, M. Molham (NRIAG), R. Inasaridze, R. Natsvlishvili, N. Kochiashvili, V. Aivazyan (AbAO), A. Baransky, Y. Romanyuk, O. Sokoliuk, A. Simon, V. Vasylenko (Lisnyky) report on behalf of the GRANDMA collaboration:
GRANDMA observed the field of GRB 230812B (Lesage et al. GCN 34387; Scotton et al. GCN 34392; Page GCN 34394; Zheng
& Filippenko GCN 34395; Lipunov et al. GCN 34396; Ackley et al. GCN 34398; Xiong et al. GCN 34401; Casentini et al. 34402; Frederiks et al. 34403; Mao et al. 34404; Odeh et al. 34405; Moskvitin & Spiridonova 34406; Leonini et al. 34408; de Ugarte Postigo et al. 34409; de Ugarte Postigo et al. 34410; Belkin et al. 34412; Ruocco et al. 34413; Frederiks et al. 34414; Ruocco et al. 34415; Shrestha et al. 34416; Quadri et al. 34417; Adami et al. 34418; Moretti et al. 34419; Kumar et al. 34420; Belkin et al. 34421)
in particular ZTF23aaxeacr candidate afterglow (16:36:31.483 +47:51:32.26) (Salgundi et al. GCN 34397)
The first observation began about 22.56 hours from the trigger.
As time reference (T0), we choose: 2023-08-12T18:58:12 (60168.79041667 MJD) (Fermi GBM Team 34386)
In the following table we report a subset of the preliminary photometry
of our observations. Magnitudes and upper limits are reported
in the AB system.
ZTF23aaxeacr:
T-T0 (day) |MJD |Obser. |Exposure| Filter | Mag +/- err |Upp.Lim. (AB)
--------------------------------------------------------------------------
0.940|60169.73055556 |Abastumani-T70|46X60s |sdssr|20.35+/-0.12|21.3 (5sig)
0.959|60169.75012731 | KAO |10X180s|sdssg|20.53+/-0.05|21.7 (5sig)
0.988|60169.77848380 | KAO |10X180s|sdssr|20.23+/-0.05|21.5 (5sig)
1.021|60169.81137731 | KAO |20X150s|sdssi|20.17+/-0.03|22.3 (5sig)
1.115|60169.90562500 | FRAM-CTA-N |50X60s | R | - |>19.1 (Vega)
KAO data has been calibrated with respect to the PS1 catalog.
Abastumani-T70 data has been calibrated with respect to the PS1 catalog, with the Johnson cousin conversion into sloan r.
FRAM-CTA-N data has been calibrated with respect to the APASS catalog.
GRANDMA is a worldwide coordinated telescope network
(grandma.ijclab.in2p3.fr) devoted to the observation of transients
in the context of multi-messenger astrophysics (Antier et al. 2020 MNRAS
497, 5518). Kilonova-Catcher (KNC) is the citizen science program of
GRANDMA (http://kilonovacatcher.in2p3.fr/).
GCN Circular 34427
Subject
GRB 230812B: Upper limits from a neutrino search with IceCube
Date
2023-08-14T22:45:46Z (2 years ago)
From
Jessie Thwaites at IceCube/U Wisc-Madison <thwaites@wisc.edu>
Via
Web form
The IceCube Collaboration (http://icecube.wisc.edu/) reports:
IceCube has performed a search for track-like muon neutrino events arriving from the direction of GRB 230812B (GCN Circular 34391 (Fermi-GBM), 34392 (Fermi-LAT)) at the position determined by Swift-XRT (GCN Circular 34394) in a time range of -1 hour/+2 hours from the initial trigger reported by Fermi-GBM (T0=2023-08-12 18:58:12.05 UTC) during which IceCube was collecting good quality data.
Zero track-like events are found to coincide with the position of the GRB. We accordingly derive a time-integrated muon-neutrino flux upper limit for this source of E^2 dN/ dE = 5.1 x 10^-2 GeV cm^-2 at 90% CL, under the assumption of an E^-2 power law. 90% of events IceCube would detect from a source at this declination with an E^-2 spectrum have energies in the approximate energy range between 600 GeV and 300 TeV.
A subsequent search was performed including 2 days of data centered on the Fermi-GBM trigger (2023-08-11 18:58:12.05 UTC to 2023-08-13 18:58:12.05 UTC). In this case, we report a p-value of 1.0, consistent with background expectation. We accordingly derive a time-integrated muon-neutrino flux upper limit for this source of E^2 dN/ dE = 5.4 x 10^-2 GeV cm^-2 at 90% CL, under the assumption of an E^-2 power law.
The IceCube Neutrino Observatory is a cubic-kilometer neutrino detector operating at the geographic South Pole, Antarctica. The IceCube realtime alert point of contact can be reached at roc@icecube.wisc.edu.
[1] IceCube Collaboration, R. Abbasi et al., ApJ 910 4 (2021)
GCN Circular 34428
Subject
GRB 230812B: further SAO RAS optical observations
Date
2023-08-15T00:02:33Z (2 years ago)
From
Moskvitin Alexander at SAO RAS <mosk@sao.ru>
Via
legacy email
A. S. Moskvitin and O. I. Spiridonova (SAO RAS), report on behalf of
the GRB follow-up team.
We observed the field of GRB 230812B (Lesage et al., GCN 34387;
Scotton et al., GCN 34392; Page, GCN 34394; Zheng & Filippenko, GCN
34395; Lipunov et al., GCN 34396; Salgundi et al., GCN 34397; Ackley
et al., GCN 34398; Xiong et al., GCN 34401; Casentini et al., GCN
34002; Frederiks et al., GCN 34403; Mao et al., GCN 34404; Odeh et
al., GCN 34405; Moskvitin & Spiridonova GCN 34406; Leonini et al. GCN
34408; de Ugarte Postigo et al. GCN 34409; de Ugarte Postigo et al.
GCN 34410; Belkin et al. GCN 34412; Ruocco et al. GCN 34413; Frederiks
et al. GCN 34414; Ruocco et al. GCN 34415; Shrestha et al. GCN 34416;
Quadri et al. GCN 34417; Adami et al. GCN 34418; Moretti et al. GCN
34419; Kumar et al. GCN 34420; Belkin et al. GCN 34421 & GCN 34423;
Pyshna et al., GCN 34425) with the 1-m telescope of SAO RAS Zeiss-1000
equipped with the CCD photometer. We obtained 5 x 300 sec. images in
Rc band on August 14, 19:51:04--20:21:03 UT
The OT is clearly detected in our stacked frame with the brightness of
R = 21.20 +/- 0.09 (t_mid - t0 = 2.0471 days).
This preliminary photometry is based on the nearby SDSS stars;
magnitudes are converted using Lupton (2005) equations.
GCN Circular 34430
Subject
GRB 230812B: Further Bassano Bresciano Observatory optical observations
Date
2023-08-15T09:18:46Z (2 years ago)
From
Ulisse Quadri at Bassano Bresciano Obs <oabb@ulisse.bs.it>
Via
legacy email
U.Quadri and L.Strabla (Bassano Bresciano Astronomical Observatory),
Members of:
AAVSO - American Association of Variable Star Observers.
UAI/SSV - Unione Astrofili Italiani/sezione stelle variabili-GRB.
GAC - Gruppo Astrofili Cremonesi.
In a large collaboration with:
M.G. Dainotti (National Astronomical Observatory of Japan),
Y. Niino (Tokyo University, Institute of Astronomy),
K. Kalinowski (Aarhus University, Department of Physics and Astronomy),
B. De Simone (Universita' degli Studi Di Salerno)
report:
We re-observed the field of GRB 230812B (Lesage et al., GCN 34387;
Scotton et al., GCN 34392; Page, GCN 34394; Zheng & Filippenko, GCN
34395; Lipunov et al., GCN 34396; Salgundi et al., GCN 34397; Ackley
et al., GCN 34398; Xiong et al., GCN 34401; Casentini et al., GCN
34002; Frederiks et al., GCN 34403; Mao et al., GCN 34404; Odeh et
al., GCN 34405; Moskvitin & Spiridonova GCN 34406; Leonini et al. GCN
34408; de Ugarte Postigo et al. GCN 34409; de Ugarte Postigo et al.
GCN 34410; Belkin et al. GCN 34412; Ruocco et al. GCN 34413; Frederiks
et al. GCN 34414; Ruocco et al. GCN 34415; Shrestha et al. GCN 34416;
Quadri et al. GCN 34417; Adami et al. GCN 34418; Moretti et al. GCN
34419; Kumar et al. GCN 34420; Belkin et al. GCN 34421 & GCN 34423;
Pyshna et al., GCN 34425) with our 0.25-m Newton robotic telescope.
We coadded 155 x 60 sec. unfiltered images on August 14 2023,
from 19:46:11 to 22:32:27 UT
We confirm a fading afterglow at the following coordinates +/- 0.2 arcsec:
RA (J2000.0) = 16h 36m 31.51s
DEC(J2000.0) = +47d 51p 32.2s
The results of OT photometry are:
-----------------------------------
JD mag Err Flt
-----------------------------------
2460171.43558 20.5 +/- 0.3 CR
CR is unfiltered with Rc zero point.
Magnitudes were estimated with the Pan-STARRS cat.
and are converted using Lupton (2005) equations.
Not corrected for galactic dust extinction.
Reference:
http://www.osservatoriobassano.org/GRB.asp
The message may be cited.
GCN Circular 34431
Subject
GRB 230812B: Optical observaions from Rozhen Observatory
Date
2023-08-15T09:34:23Z (2 years ago)
From
Eslam Elhosseiny at NRIAG <eslam_elhosseiny@nriag.sci.eg>
Via
Web form
B. Mihov, L. Slavcheva-Mihova (Institute of Astronomy and NAO, Bulgaria),
Eslam G. Elhosseiny, Ali Takey (National Research Institute of Astronomy and Geophysics (NRIAG), Egypt)
We observed the field of GRB 230812B, detected by Fermi GBM team (GCN 34386; GCN 34387) with the 50/70 cm Schmidt telescope at Rozhen NAO, Bulgaria. The observations started at 19:43 UT of 2023-08-13, 24.75 hours after Fermi detection. We took 18 images with 180 sec in I-band. The stacked image was calibrated in Cousins I-band after transformation from the PS1 catalogue. The counterpart of GRB 230812B was detected with 19.82 +/- 0.15 mag at the position of RA and Dec as 16° 36' 31.5" and 47° 51' 31.81" respectively, which is within the uncertainty of the X-ray position (GCN 34400).
GCN Circular 34432
Subject
GRB 230812B: continued AbAO optical afterglow observations
Date
2023-08-15T09:36:05Z (2 years ago)
From
Alexei Pozanenko at IKI, Moscow <apozanen@iki.rssi.ru>
Via
legacy email
S. Belkin (IKI), R. Ya. Inasaridze (AbAO), A. Pozanenko (IKI), N. Pankov (HSE, IKI) report on behalf of GRB IKI FuN:
We observed the field of GRB 230812B (Fermi GBM Team, GCN 34386; Scotton et al., GCN 34392; Page et al. GCN 34394; Kuin et al., GCN 34399; Casentini et al., GCN 34402) with AS-32 telescope of Abastumani observatory (AbAO) in R-filter starting on Aug. 14 (UT) 17:47:21. We detected the afterglow (Lesage et al., GCN 34387; Scotton et al., GCN 34392; Page, GCN 34394; Zheng & Filippenko, GCN 34395; Lipunov et al., GCN 34396; Salgundi et al., GCN 34397; Ackley et al., GCN 34398; Xiong et al., GCN 34401; Casentini et al., GCN 34402; Frederiks et al., GCN 34403; Mao et al., GCN 34404; Odeh et al., GCN 34405; Moskvitin et al., GCN 34406; Leonini et al., GCN 34408; de Ugarte Postigo et al., GCNs 24409, 34410; Belkin et al. GCN 34412; Ruocco et al. GCN 34413; Frederiks et al. GCN 34414; Ruocco et al. GCN 34415; Shrestha et al. GCN 34416; Quadri et al. GCN 34417; Adami et al. GCN 34418; Moretti et al. GCN 34419; Kumar et al. GCN 34420; Belkin et al. GCN 34421 & GCN 34423; Pyshna et al!
., GCN 34425) in the stacked image. Preliminary photometry of the object is following
Date UT start t-T0 Filter Exp. OT Err. UL(3sigma)
(mid, days) (s)
2023-08-14 17:47:21 1.99199 R 94*60 21.16 0.21 22.0
The photometry is based on nearby SDSS stars used in (Moskvitin et al, GCN 34406):
RA DEC R (Lupton)
16:36:35.9365104 +47:52:54.574320 14.893 0.008
16:36:32.6835360 +47:53:44.537784 16.531 0.009
16:36:25.6055880 +47:53:20.456304 16.827 0.009
16:36:25.1691816 +47:52:20.931816 16.068 0.008
16:36:44.6580984 +47:50:56.806944 15.785 0.008
16:36:40.1374488 +47:54:02.128752 15.698 0.008
GCN Circular 34433
Subject
GRB 230812B: AMI-LA radio detection of afterglow candidate
Date
2023-08-15T10:57:05Z (2 years ago)
From
Lauren Rhodes at Oxford <lauren.rhodes@physics.ox.ac.uk>
Via
legacy email
Lauren Rhodes, Joe Bright, Rob Fender (Oxford), Dave Green, Dave Titterington (Cambridge) report:
We observed the field of the gamma-ray burst GRB 230812B (GCN 34286) with the Arcminute Microkelvin Imager Large-Array (AMI-LA) at 15.5 GHz beginning at UT 18:13:51.9 on 14-Aug-2023 for a total of 4 hours. The flux standard 3c286 was used to calibrate the bandpass response and flux scale of the AMI-LA and J1658+4737 was used as an interleaved complex gain calibrator.
We detect a unresolved source at a position consistent with the one reported in GCN 34394 with a (preliminary) peak flux density of 280uJy/beam. The rms noise in the field is 40uJy/beam. Further observations are planned.
We thank the staff at the Mullard Radio Astronomy Observatory for carrying out these observations and operating the AMI-LA.
GCN Circular 34435
Subject
GRB 230812B: Tautenburg observations
Date
2023-08-15T13:55:41Z (2 years ago)
From
Sylvio Klose at TLS Tautenburg <klose@tls-tautenburg.de>
Via
email
S. Klose, S. Melnikov, B. Stecklum, A. Nicuesa Guelbenzu, and F. Ludwig (all TLS Tautenburg) report:
We observed the field of GRB 230812B (Lesage et al., GCN 34387; Roberts et al., GCN 34391; Scotton et al., GCN 34392; Xiong et al., GCN 34401; Casentini et al., GCN 34402; Frederiks et al., GCN 34403) with the Tautenburg 1.34m Schmidt telescope equipped with the TAUKAM 6k x 6k CCD camera. Observations consisted of 3 x 90 sec exposures using the Sloan g, r, and i-band filter.
For the optical transient (first reported by Zheng et al., GCN 34395, and Lipunov et al, GCN 34396) we measure the following preliminary AB magnitudes (2.19 days post burst):
g = 21.85 +/- 0.25 (midtime: August 14, 2023, 23:23:33 UT),
r = 21.28 +/- 0.13 (midtime: August 14, 2023, 23:30:37 UT),
i = 21.29 +/- 0.14 (midtime: August 14, 2023, 23:37:44 UT),
calibrated against SDSS stars in the field.
GCN Circular 34436
Subject
GRB 230812B: Iota Scorpii Observatory, La Spezia, Italy
Date
2023-08-15T14:09:22Z (2 years ago)
From
GIULIO SCARFI at IOTA SCORPII OBSERVATORY <terziaria@gmail.com>
Via
legacy email
Giulio Scarfì (Iota Scorpii Observatory, La Spezia,Italy)
mail terziaria@gmail.com
In a large collaboration with:
M.G. Dainotti (National Astronomical Observatory of Japan),
Y. Niino (Tokyo University, Institute of Astronomy),
K. Kalinowski (Aarhus University, Department of Physics and Astronomy),
B. De Simone (Universita' degli Studi Di Salerno)
Members of:
GAD - Gruppo Astronomia Digitale.
AAVSO - American Association of Variable Star Observers.
UAI/SSV - Unione Astrofili Italiani/sezione stelle variabili-GRB.
report:
I have observed the field of GRB 230812B (Lesage et al., GCN 34387;
Scotton et al., GCN 34392; Page, GCN 34394; Zheng & Filippenko, GCN
34395; Lipunov et al., GCN 34396; Salgundi et al., GCN 34397; Ackley
et al., GCN 34398; Xiong et al., GCN 34401; Casentini et al., GCN
34002; Frederiks et al., GCN 34403; Mao et al., GCN 34404; Odeh et
al., GCN 34405; Moskvitin & Spiridonova GCN 34406; Leonini et al. GCN
34408; de Ugarte Postigo et al. GCN 34409; de Ugarte Postigo et al.
GCN 34410; Belkin et al. GCN 34412; Ruocco et al. GCN 34413; Frederiks
et al. GCN 34414; Ruocco et al. GCN 34415; Shrestha et al. GCN 34416;
Quadri et al. GCN 34417; Adami et al. GCN 34418; Moretti et al. GCN
34419; Kumar et al. GCN 34420; Belkin et al. GCN 34421 & GCN 34423;
Pyshna et al., GCN 34425) with my 0.40-m Ritchey-Cretien telescope.
The observations started 1660 min after the GRB trigger, at the end of
twilight,
with a Ritchey Cretien D=406 mm with reducer F/D=6,15.
Weather conditions were good.
Add 12 x 300 sec. unfiltered images on August 13 2023,
from 20:26:35 to 21:21:42 UT
Start T0+ End T0+ R lim
1660 min 1735 min 20
I confirm a fading afterglow
The results of photometry are:
JD mag Err Flt
2460170.36555307 19.85 +/- 0.2 CLEAR
Magnitudes were estimated with the Atlas catalog and
are not corrected for galactic dust extinction.
Reference:
http://www.iotascorpiiobservatory.it
The message may be cited.
GCN Circular 34442
Subject
GRB 230812B: continued SAO RAS optical observation
Date
2023-08-16T01:28:09Z (2 years ago)
From
Moskvitin Alexander at SAO RAS <mosk@sao.ru>
Via
legacy email
A. S. Moskvitin and O. I. Spiridonova (SAO RAS),
report on behalf of the GRB follow-up team.
We observed the field of GRB 230812B (Fermi GBM Team, GCN 34386;
Scotton et al., GCN 34392; Page et al. GCN 34394; Kuin et al.,
GCN 34399; Casentini et al., GCN 34402) with the 1-m telescope
of SAO RAS Zeiss-1000 equipped with the CCD photometer. We obtained
8 x 300 sec. images in Rc band on 19:02:23--20:57:14 UT and
8 x 300 sec. images in B band on 19:45:22--21:08:27 UT (August 15).
The OT (Lesage et al., GCN 34387; Scotton et al., GCN 34392; Page,
GCN 34394; Zheng & Filippenko, GCN 34395; Lipunov et al., GCN 34396;
Salgundi et al., GCN 34397; Ackley et al., GCN 34398; Xiong et al.,
GCN 34401; Casentini et al., GCN 34402; Frederiks et al., GCN 34403;
Mao et al., GCN 34404; Odeh et al., GCN 34405; Moskvitin & Spiridonova,
GCN 34406; Leonini et al., GCN 34408; de Ugarte Postigo et al.,
GCNs 24409, 34410; Belkin et al. GCN 34412; Ruocco et al. GCN 34413;
Frederiks et al. GCN 34414; Ruocco et al. GCN 34415; Shrestha et al.
GCN 34416; Quadri et al. GCN 34417; Adami et al. GCN 34418;
Moretti et al. GCN 34419; Kumar et al. GCN 34420; Belkin et al. GCNs
34421, GCN 34423; Pyshna et al., GCN 34425; Moskvitin & Spiridonova,
GCN 34428; Quadri & Strabla, GCN 34430; Mihov et al., GCN 34431;
Belkin et al. GCN 34432; Klose et al., GCN 34435; Scarfi, GCN 34436)
is clearly detected in our stacked frames with the brightness of
R = 21.40 +/- 0.06 (t_mid - t0 = 3.0428 days),
B = 22.23 +/- 0.09 (t_mid - t0 = 3.0616 days).
This preliminary photometry is based on the nearby SDSS stars;
magnitudes are converted using Lupton (2005) equations.
GCN Circular 34443
Subject
GRB 230812B: iTelescope optical upper limit
Date
2023-08-16T04:27:25Z (2 years ago)
From
Filipp Dmitrievich Romanov at Amateur astronomer <filipp.romanov.27.04.1997@gmail.com>
Via
legacy email
I observed the field of GRB 230812B (Fermi GBM team, GCN Circ. 34386)
remotely using telescope T24 (0.61-m f/6.5 reflector + CCD) of
iTelescope.Net in Sierra Remote Observatory (Auberry, California, USA)
on 2023-08-14. Six images (exposures 300 seconds, BINx1) were obtained
with Ic filter with mid time 05:10:04 UT (1.424 d. after the trigger).
I did not detect any optical afterglow in the Swift/XRT (Page, GCN
Circ. 34394) position. The magnitude limit is about 19 mag, compared
to the magnitudes of nearby stars from the USNO-B1.0 Catalog (Monet et
al., 2003).
F. D. Romanov (AAVSO member, observer code: RFDA).
GCN Circular 34445
Subject
GRB 230812B: GAD Observatory optical observations (upper limit)
Date
2023-08-16T10:38:15Z (2 years ago)
From
Claudio Lopresti <cl3lop@gmail.com>
Via
legacy email
Claudio Lopresti (Gruppo Astronomia Digitale - GAD Observatory, La Spezia, Italy),
in a large collaboration with:
M.G. Dainotti (National Astronomical Observatory of Japan),
Y. Niino (Tokyo University, Institute of Astronomy),
K. Kalinowski (Aarhus University, Department of Physics and Astronomy),
B. De Simone (Universita' degli Studi Di Salerno)
report:
I imaged the field of GRB 230812B (Lesage et al., GCN 34387;
Scotton et al., GCN 34392; Page, GCN 34394; Zheng & Filippenko, GCN 34395;
Lipunov et al., GCN 34396; Salgundi et al., GCN 34397; Ackley et al., GCN 34398;
Xiong et al., GCN 34401; Casentini et al., GCN 34002; Frederiks et al., GCN 34403;
Mao et al., GCN 34404; Odeh et al., GCN 34405; Moskvitin et al., GCN 34406)
detected by FERMI(trigger 713559497.049606 / 230812790)
with the GAD Observatory, La Spezia, Italy Italy.
Member of:
UAI/SSV - Unione Astrofili Italiani/sezione stelle variabili, GRB section
GAD - Gruppo Astronomia Digitale
The observations started 48.02 hour after the FERMI trigger, At the end of twilight
with a Maksutov-Newton telescope D=180 mm F/D=4
Weather conditions were good.
We co-added series of 8 exposures of 60 sec each.
Start T0+ End T0+ R lim
3168 min 3178 min 19.6
I did not detect any optical afterglow in the Swift/XRT (Page, GCN
Circ. 34387) position. The magnitude limit is about 19.5 mag, compared
to the magnitudes of nearby stars from the Gaia EDR3 Catalog
Magnitudes were estimated with the Gaia EDR3 cat. and
are not corrected for galactic dust extinction.
Reference:
https://www.parcodellestelle.com/
The message may be cited.
GCN Circular 34461
Subject
GRB 230812B: SAO RAS optical observations
Date
2023-08-16T22:32:47Z (2 years ago)
From
Moskvitin Alexander at SAO RAS <mosk@sao.ru>
Via
legacy email
A. S. Moskvitin and O. I. Spiridonova (SAO RAS),
report on behalf of the GRB follow-up team.
We observed the field of GRB 230812B (Fermi GBM Team, GCN 34386;
Scotton et al., GCN 34392; Page et al. GCN 34394; Kuin et al.,
GCN 34399; Casentini et al., GCN 34402) with the 1-m telescope
of SAO RAS Zeiss-1000 equipped with the CCD photometer. We obtained
8 x 300 sec. images in Rc band on 19:46:41--20:32:24 UT (August 17).
The OT (Lesage et al., GCN 34387; Scotton et al., GCN 34392; Page,
GCN 34394; Zheng & Filippenko, GCN 34395; Lipunov et al., GCN 34396;
Salgundi et al., GCN 34397; Ackley et al., GCN 34398; Xiong et al.,
GCN 34401; Casentini et al., GCN 34402; Frederiks et al., GCN 34403;
Mao et al., GCN 34404; Odeh et al., GCN 34405; Moskvitin & Spiridonova,
GCN 34406; Leonini et al., GCN 34408; de Ugarte Postigo et al.,
GCNs 24409, 34410; Belkin et al. GCN 34412; Ruocco et al. GCN 34413;
Frederiks et al. GCN 34414; Ruocco et al. GCN 34415; Shrestha et al.
GCN 34416; Quadri et al. GCN 34417; Adami et al. GCN 34418;
Moretti et al. GCN 34419; Kumar et al. GCN 34420; Belkin et al. GCNs
34421, GCN 34423; Pyshna et al., GCN 34425; Moskvitin & Spiridonova,
GCN 34428; Quadri & Strabla, GCN 34430; Mihov et al., GCN 34431;
Belkin et al. GCN 34432; Klose et al., GCN 34435; Scarfi, GCN 34436;
Moskvitin & Spiridonova, GCN 34442) is clearly detected in our stacked
frame with the brightness of R = 21.46 +/- 0.06 (t_mid - t0 = 4.0496d).
This preliminary photometry is based on the nearby SDSS stars;
magnitudes are converted using Lupton (2005) equations.
GCN Circular 34463
Subject
GRB 230812B: optical photometry from Konkoly
Date
2023-08-17T10:23:01Z (2 years ago)
From
Jozsef Vinko at Konkoly Observator <vinko@konkoly.hu>
Via
legacy email
J. Vinko, L. Kriskovics, A. Pal, R. Szakats
(Konkoly Observatory, Hungary).
We report detection and photometry of the optical afterglow of GRB230812B (Fermi GBM Team, GCN 34386;
Scotton et al., GCN 34392; Page et al. GCN 34394; Kuin et al.,GCN 34399; Casentini et al., GCN 34402)
with the RC80 robotic telescope at Piszkesteto Station of Konkoly
Observatory taken on 2023-08-13 to 2023-08-15. A series of 300 sec
frames were collected through Sloan r'- and i' bands. The optical afterglow
(Lesage et al., GCN 34387; Scotton et al., GCN 34392; Page,
GCN 34394; Zheng & Filippenko, GCN 34395; Lipunov et al., GCN 34396;
Salgundi et al., GCN 34397; Ackley et al., GCN 34398; Xiong et al.,
GCN 34401; Casentini et al., GCN 34402; Frederiks et al., GCN 34403;
Mao et al., GCN 34404; Odeh et al., GCN 34405; Moskvitin & Spiridonova,
GCN 34406; Leonini et al., GCN 34408; de Ugarte Postigo et al.,
GCNs 24409, 34410; Belkin et al. GCN 34412; Ruocco et al. GCN 34413;
Frederiks et al. GCN 34414; Ruocco et al. GCN 34415; Shrestha et al.
GCN 34416; Quadri et al. GCN 34417; Adami et al. GCN 34418;
Moretti et al. GCN 34419; Kumar et al. GCN 34420; Belkin et al. GCNs
34421, GCN 34423; Pyshna et al., GCN 34425; Moskvitin & Spiridonova,
GCN 34428; Quadri & Strabla, GCN 34430; Mihov et al., GCN 34431;
Belkin et al. GCN 34432; Klose et al., GCN 34435; Scarfi, GCN 34436;
Moskvitin & Spiridonova, GCN 34442, GCN 34461)
was detected on the stacked frames with the following magnitudes, calibrated
via nearby PS1 stars:
Date UT-middle t-T0(hr) Exp(s) r'(AB-mag) i'(AB-mag)
2023-08-13 19:41:01 24.71 1500 20.47 (0.10) 19.75 (0.12)
2023-08-14 19:40:32 48.71 1500 21.33 (0.20) 20.51 (0.19)
2023-08-15 21:50:01 74.86 900 >21.89 >21.45
The magnitudes above are not corrected for galactic extinction.
GCN Circular 34468
Subject
GRB 230812B: NOEMA detection
Date
2023-08-17T18:26:36Z (2 years ago)
From
Antonio de Ugarte Postigo at OCA <deugarte@oca.eu>
Via
legacy email
A. de Ugarte Postigo, (OCA-CNRS), J. M. Winters (IRAM), C. C. Thoene (ASU-CAS), S. Antier (OCA), J. F. Agui-Fernandez (IAA-CSIC), M. Bremer (IRAM), D. A. Perley (LJMU), S. Martin (ESO, ALMA) report,
We observed the afterglow of GRB 230812B (Roberts et al. GCN34391, Scotton et al. GCN 34392, Zheng & Filippenko GCN 34395, Beardmore et al. GCN 34400) with NOEMA in the 3mm band. The observation started on August 16 at 13:49 UT (3.79 days after the burst) and included observations at 75 and 89.5 GHz side bands.
The afterglow, previously detected in radio by AMI-LA (Rhodes et al. GCN34433) is weakly detected at 75 GHz with a flux density of 0.14 mJy. At a redshift of z = 0.36 (de Ugarte Postigo et al. GCN 34409) the afterglow currently has a luminosity of <10^30 erg/s/Hz which is amongst the least luminous afterglows detected at these frequencies.
GCN Circular 34471
Subject
GRB 230812B: SAO RAS optical observations
Date
2023-08-17T23:46:52Z (2 years ago)
From
Moskvitin Alexander at SAO RAS <mosk@sao.ru>
Via
legacy email
A. S. Moskvitin and O. I. Spiridonova (SAO RAS),
report on behalf of the GRB follow-up team.
We observed the field of GRB 230812B (Fermi GBM Team, GCN 34386;
Scotton et al., GCN 34392; Page et al. GCN 34394; Kuin et al.,
GCN 34399; Casentini et al., GCN 34402) with the 1-m telescope
of SAO RAS Zeiss-1000 equipped with the CCD photometer. We obtained
12 x 300 sec. images in Rc band on 21:14:58--22:26:52 UT (August 17).
In the previous GCN 34461 we have a typo in date, the correct date is
August 16. We apologize for the possible confusion and inconvenience.
The OT (Lesage et al., GCN 34387; Scotton et al., GCN 34392; Page,
GCN 34394; Zheng & Filippenko, GCN 34395; Lipunov et al., GCN 34396;
Salgundi et al., GCN 34397; Ackley et al., GCN 34398; Xiong et al.,
GCN 34401; Casentini et al., GCN 34402; Frederiks et al., GCN 34403;
Mao et al., GCN 34404; Odeh et al., GCN 34405; Moskvitin & Spiridonova,
GCN 34406; Leonini et al., GCN 34408; de Ugarte Postigo et al.,
GCNs 24409, 34410; Belkin et al. GCN 34412; Ruocco et al. GCN 34413;
Frederiks et al. GCN 34414; Ruocco et al. GCN 34415; Shrestha et al.
GCN 34416; Quadri et al. GCN 34417; Adami et al. GCN 34418;
Moretti et al. GCN 34419; Kumar et al. GCN 34420; Belkin et al. GCNs
34421, GCN 34423; Pyshna et al., GCN 34425; Moskvitin & Spiridonova,
GCN 34428; Quadri & Strabla, GCN 34430; Mihov et al., GCN 34431;
Belkin et al. GCN 34432; Klose et al., GCN 34435; Scarfi, GCN 34436;
Moskvitin & Spiridonova, GCNs 34442, 34461; Vinko et al., GCN 34463)
is clearly detected in our stacked frame with the brightness of
R = 21.79 +/- 0.09 (t_mid - t0 = 5.1199 days).
This preliminary photometry is based on the nearby SDSS stars;
magnitudes are converted using Lupton (2005) equations.
We are grateful to the SAO RAS staff for their technical support.
GCN Circular 34475
Subject
GRB 230812B: SAO RAS observations, possible re-brightening
Date
2023-08-18T22:28:55Z (2 years ago)
From
Moskvitin Alexander at SAO RAS <mosk@sao.ru>
Via
legacy email
A. S. Moskvitin and O. I. Spiridonova (SAO RAS),
report on behalf of the GRB follow-up team.
We observed the field of GRB 230812B (Fermi GBM Team, GCN 34386;
Scotton et al., GCN 34392; Page et al. GCN 34394; Kuin et al.,
GCN 34399; Casentini et al., GCN 34402) with the 1-m telescope
of SAO RAS Zeiss-1000 equipped with the CCD photometer. We obtained
12 x 300 sec. images in Rc band on 20:13:25--21:49:22 UT (August 18).
The OT (Lesage et al., GCN 34387; Scotton et al., GCN 34392; Page,
GCN 34394; Zheng & Filippenko, GCN 34395; Lipunov et al., GCN 34396;
Salgundi et al., GCN 34397; Ackley et al., GCN 34398; Xiong et al.,
GCN 34401; Casentini et al., GCN 34402; Frederiks et al., GCN 34403;
Mao et al., GCN 34404; Odeh et al., GCN 34405; Moskvitin & Spiridonova,
GCN 34406; Leonini et al., GCN 34408; de Ugarte Postigo et al.,
GCNs 24409, 34410; Belkin et al. GCN 34412; Ruocco et al. GCN 34413;
Frederiks et al. GCN 34414; Ruocco et al. GCN 34415; Shrestha et al.
GCN 34416; Quadri et al. GCN 34417; Adami et al. GCN 34418;
Moretti et al. GCN 34419; Kumar et al. GCN 34420; Belkin et al. GCNs
34421, GCN 34423; Pyshna et al., GCN 34425; Moskvitin & Spiridonova,
GCN 34428; Quadri & Strabla, GCN 34430; Mihov et al., GCN 34431;
Belkin et al. GCN 34432; Klose et al., GCN 34435; Scarfi, GCN 34436;
Moskvitin & Spiridonova, GCNs 34442, 34461, 34471; Vinko et al.,
GCN 34463) is clearly detected in our stacked frame with
the brightness of R = 21.46 +/- 0.06 (t_mid - t0 = 6.0856 days).
This preliminary photometry is based on the nearby SDSS stars;
magnitudes are converted using Lupton (2005) equations.
GCN Circular 34496
Subject
GRB 230812B: SAO RAS Zeiss-1000 observations
Date
2023-08-19T20:09:24Z (2 years ago)
From
Moskvitin Alexander at SAO RAS <mosk@sao.ru>
Via
legacy email
A. S. Moskvitin (SAO RAS), V. P. Goranskij (SAI MSU),
report on behalf of the GRB follow-up team.
We observed the field of GRB 230812B (Fermi GBM Team, GCN 34386;
Scotton et al., GCN 34392; Page et al. GCN 34394; Kuin et al.,
GCN 34399; Casentini et al., GCN 34402) with the 1-m telescope
of SAO RAS Zeiss-1000 equipped with the CCD photometer. We obtained
6 x 300 sec. images in Rc band on August 19, 18:11:41--18:45:30 UT.
The OT (Lesage et al., GCN 34387; Scotton et al., GCN 34392; Page,
GCN 34394; Zheng & Filippenko, GCN 34395; Lipunov et al., GCN 34396;
Salgundi et al., GCN 34397; Ackley et al., GCN 34398; Xiong et al.,
GCN 34401; Casentini et al., GCN 34402; Frederiks et al., GCN 34403;
Mao et al., GCN 34404; Odeh et al., GCN 34405; Moskvitin & Spiridonova,
GCN 34406; Leonini et al., GCN 34408; de Ugarte Postigo et al.,
GCNs 24409, 34410; Belkin et al. GCN 34412; Ruocco et al. GCN 34413;
Frederiks et al. GCN 34414; Ruocco et al. GCN 34415; Shrestha et al.
GCN 34416; Quadri et al. GCN 34417; Adami et al. GCN 34418;
Moretti et al. GCN 34419; Kumar et al. GCN 34420; Belkin et al. GCNs
34421, GCN 34423; Pyshna et al., GCN 34425; Moskvitin & Spiridonova,
GCN 34428; Quadri & Strabla, GCN 34430; Mihov et al., GCN 34431;
Belkin et al. GCN 34432; Klose et al., GCN 34435; Scarfi, GCN 34436;
Moskvitin & Spiridonova, GCNs 34442, 34461, 34471, 34475;
Vinko et al., GCN 34463) is clearly detected in our stacked frame
with the brightness of R = 21.8 +/- 0.1 (t_mid - t0 = 6.9794 days).
This preliminary photometry is based on the nearby SDSS stars;
magnitudes are converted using Lupton (2005) equations.
GCN Circular 34500
Subject
GRB 230812B: GIT Confirmation of SN rise
Date
2023-08-20T09:45:51Z (2 years ago)
From
Vishwajeet Swain at IIT Bombay <vishwajeet.s@iitb.ac.in>
Via
Web form
H. Kumar (IITB), V. Swain (IITB), R. Teja (IIA), R. Kumar (IITB), A. Salgundi (IITB), V. Bhalerao (IITB), G.C. Anupama (IIA), D.K. Sahu (IIA), S. Barway (IIA) and K. Angail (IAO) report on behalf of the GIT team:
We continued observation of the field of the GRB230812B (Fermi GBM Team, GCN 34386) with 0.7m GROWTH-India Telescope (GIT). Starting at 15:26:30 UT on 2023-08-19, we took 18 exposures of 300 sec each in r' band and detected the optical source in our stacked images. We also observed the target with HCT (2x 25 min, PI: R Teja), and detect the source as well. The details of the photometry are given in the below table:
-------------------------------------------------------
JD (mid) | T-T0 (days)| Filter | Exposure (s) | Magnitude (AB) | Telescope
-------------------------------------------------------
2460176.199743 | 6.90 | r' | 18 x 300 | 22.06 +/- 0.10 | GIT
2460176.196935 | 6.91 | r' | 2 x 1500 | 22.04 +/- 0.18 | HCT
-------------------------------------------------------
Our photometry shows a significant deviation from the earlier estimated power-law decay (alpha = 1.23 +/- 0.04) and shows a rise by ~0.9 mag as compared to afterglow-only emission, suggesting the presence of a supernova component. Our results are consistent with A. S. Moskvitin et al., GCN 33475. Based on our SN + PL fits predict that the emission should rise slightly over next 15 days and will start decaying again once the SN peaks around T-T0 ~ 22 days.
We encourage the spectroscopic observation to confirm the presence of SN fully.
Also see: Zheng & Filippenko, GCN 34395, Lipunov et al., GCN 34396, Salgundi et al., GCN 34397, Ackley et al., GCN 34398, Kuin et al. GCN 34399, Mao et al., GCN 34404, Odeh et al., GCN 34405, Moskvitin et al., GCN 34406, Leonini et al., GCN 34408, de Ugarte Postigo et al. GCN 34409, 34410 & 34468, Belkin et al., GCN 34412, and N. Ruocco et al., GCN 34413, N. Ruocco et al., GCN 34413, M. Shrestha et al., GCN 34416, C. Adami et al., GCN 34418, L. Moretti et al., GCN 34419, R. Kumar et al., GCN 33420, S. Belkin et al., GCN 33421, 33423, 33432, O. Pyshna et al., GCN 34425, A. S. Moskvitin et al., GCN 33428, 33442, 33461 33471, 33475 & 33496, U.Quadri and L.Strabla GCN 33430, B. Mihov et al., GCN 33431, Lauren Rhodes et al., GCN 33433, S. Klose et al., GCN 33435, Giulio Scarfì et al., GCN 33436, F.D. Romanov GCN 33443, Lopresti et al., GCN 33445, J. Vinko et al., GCN 33463.
The GROWTH India Telescope (GIT; Kumar et al. 2022) is a 70-cm telescope with a 0.7-degree field of view, set up by the Indian Institute of Astrophysics (IIA) and the Indian Institute of Technology Bombay (IITB) with funding from DST-SERB and IUSSTF. It is located at the Indian Astronomical Observatory (Hanle), operated by IIA. We acknowledge funding by the IITB alumni batch of 1994, which partially supports the operations of the telescope. Telescope technical details are available at https://sites.google.com/view/growthindia/.
GCN Circular 34508
Subject
GRB 230812B : GRANDMA/Kilonova-Catcher optical afterglow detection and upper limits
Date
2023-08-21T13:15:22Z (2 years ago)
From
Damien Turpin at CEA-Saclay <dturpin-astro@hotmail.com>
Via
Web form
D. Turpin (CEA), M. Serrau (KNC), S. Leonini (KNC), M. Freeberg (KNC),
F. D. Romanov (KNC), S. Karpov (FZU), S. Antier (OCA/Artemis) report
on behalf of the GRANDMA/Kilonova-Catcher collaboration:
The Kilonova-Catcher telescope network responded to the alert of
GRB 230812B (Fermi GBM detection: Roberts et al., GCN 34391;
Fermi LAT detection: Scotton et al., GCN 34392).
The KNC observations were taken by M. Serrau at the Chante-Perdrix
Observatory (France), S. Leonini at the Montarrenti Observatory (Italy),
M. Freeberg at the Hidden Valley Observatory (USA) and F.~D. Romanov at the
iTelescope.Net in Sierra Remote Observatory (USA).
The afterglow is first detected in 50x30s R-band coadded images at
about 1 day (midtime of the exposure) after the Fermi/GBM trigger time.
Below, we report a subset of our photometric measurements.
---------------------------------------------------------------------------------
T-T0 (midtime,day) |Exposure| Filter | Mag +/- err |Mag.Lim. (5sig AB) |Observer
---------------------------------------------------------------------------------
1.024 | 50 x 30s | Rc | 20.35 +/- 0.16 | -- | Leonini
1.164 | 15 x 180s | V | 20.74 +/- 0.08 | -- | Serrau
1.182 | 30 x 180s | Rc | 20.87 +/- 0.15 | -- | Serrau
1.425 | 6 x 300s | Ic | -- | 18.6 | Romanov
2.334 | 12 x 300s | r | -- | 20.6 | Freeberg
2.397 | 12 x 300s | i | -- | 19.3 | Freeberg
2.624 | 30 x 180s | Rc | 21.29 +/- 0.11 | -- | Serrau
4.080 | 40 x 180s | V | 22.20 +/- 0.21 | -- | Serrau
Our detections are consistent with the fading behavior previously reported
by GRANDMA Mao et al., GCN 34404; Pyshna et al., GCN 34425. We note that
the underlying host galaxy may contribute to our late photometric
measurements. The reported magnitudes are not corrected for the galactic
dust extinction in the line of sight of the burst.
The GRANDMA/Kilonova-Cacther images have been calibrated using field
stars from the PanSTARRS-DR1 catalog using the STDpipe pipeline
(Karpov 2022) and the ps1/r to Rc mag conversion from (Pancino et al. 2022).
GRANDMA is a worldwide telescope network (grandma.ijclab.in2p3.fr)
devoted to the observation of transients in the context of multi-messenger
astrophysics (Antier et al. 2020 MNRAS 497, 5518). Kilonova-Catcher (KNC) is
the citizen science program of GRANDMA (http://kilonovacatcher.in2p3.fr/).
GCN Circular 34516
Subject
GRB 230812B: SAO RAS RC-500 and Zeiss-1000 observations
Date
2023-08-21T19:58:42Z (2 years ago)
From
Moskvitin Alexander at SAO RAS <mosk@sao.ru>
Via
legacy email
A. S. Moskvitin, V. V. Vlasyuk (SAO RAS), V. P. Goranskij (SAI MSU),
report on behalf of the GRB follow-up team.
We observed the field of GRB 230812B (Fermi GBM Team, GCN 34386;
Scotton et al., GCN 34392; Page et al. GCN 34394; Kuin et al.,
GCN 34399; Casentini et al., GCN 34402) with the SAO RAS optical
telescopes RC-500 and Zeiss-1000 equipped with the CCD photometers.
We obtained 90 x 60 sec. images in Rc band with the 0.5-m telescope
on August 20, 18:36:51--20:27:56 and 6 x 300 sec. images in Rc band
with the 1-m telescope on August 20, 21:09:05--21:43:00 UT.
The OT (Lesage et al., GCN 34387; Scotton et al., GCN 34392; Page,
GCN 34394; Zheng & Filippenko, GCN 34395; Lipunov et al., GCN 34396;
Salgundi et al., GCN 34397; Ackley et al., GCN 34398; Xiong et al.,
GCN 34401; Casentini et al., GCN 34402; Frederiks et al., GCN 34403;
Mao et al., GCN 34404; Odeh et al., GCN 34405; Moskvitin & Spiridonova,
GCN 34406; Leonini et al., GCN 34408; de Ugarte Postigo et al.,
GCNs 24409, 34410; Belkin et al. GCN 34412; Ruocco et al. GCN 34413;
Frederiks et al. GCN 34414; Ruocco et al. GCN 34415; Shrestha et al.
GCN 34416; Quadri et al. GCN 34417; Adami et al. GCN 34418;
Moretti et al. GCN 34419; Kumar et al. GCN 34420; Belkin et al. GCNs
34421, GCN 34423; Pyshna et al., GCN 34425; Moskvitin & Spiridonova,
GCN 34428; Quadri & Strabla, GCN 34430; Mihov et al., GCN 34431;
Belkin et al. GCN 34432; Klose et al., GCN 34435; Scarfi, GCN 34436;
Moskvitin & Spiridonova, GCNs 34442, 34461, 34471, 34475;
Vinko et al., GCN 34463; H. Kumar et al., GCN 34500; Turpin et al.,
GCN 34508) is clearly detected in our stacked frames
with the brightness of R = 21.58 +/- 0.11 (t_mid - t0 = 8.0237 days)
and R = 21.44 +/- 0.07 (t_mid - t0 = 8.1027 days).
This preliminary photometry is based on the nearby SDSS stars;
magnitudes are converted using Lupton (2005) equations.
GCN Circular 34519
Subject
GRB 230812B: Assy optical observations, possible SN rise
Date
2023-08-22T11:49:56Z (2 years ago)
From
Alexei Pozanenko at IKI, Moscow <apozanen@iki.rssi.ru>
Via
legacy email
N. Pankov (HSE, IKI), V. Kim (FAI), A. Pozanenko (IKI), M. Krugov (FAI), S. Belkin (IKI) report on behalf of GRB IKI FuN:
We observed the field of GRB 230812B (Fermi GBM Team, GCN 34386;
Scotton et al., GCN 34392; Page et al. GCN 34394; Kuin et al.,
GCN 34399; Casentini et al., GCN 34402) with AZT-20 telescope of Assy-Turgen observatory on 2023-08-17 -- 2023-08-21.
The OT (Lesage et al., GCN 34387; Scotton et al., GCN 34392; Page,
GCN 34394; Zheng & Filippenko, GCN 34395; Lipunov et al., GCN 34396;
Salgundi et al., GCN 34397; Ackley et al., GCN 34398; Xiong et al.,
GCN 34401; Casentini et al., GCN 34402; Frederiks et al., GCN 34403;
Mao et al., GCN 34404; Odeh et al., GCN 34405; Moskvitin & Spiridonova,
GCN 34406; Leonini et al., GCN 34408; de Ugarte Postigo et al.,
GCNs 24409, 34410; Belkin et al. GCN 34412; Ruocco et al. GCN 34413;
Frederiks et al. GCN 34414; Ruocco et al. GCN 34415; Shrestha et al.
GCN 34416; Quadri et al. GCN 34417; Adami et al. GCN 34418;
Moretti et al. GCN 34419; Kumar et al. GCN 34420; Belkin et al. GCNs
34421, GCN 34423; Pyshna et al., GCN 34425; Moskvitin & Spiridonova,
GCN 34428; Quadri & Strabla, GCN 34430; Mihov et al., GCN 34431;
Belkin et al. GCN 34432; Klose et al., GCN 34435; Scarfi, GCN 34436;
Moskvitin & Spiridonova, GCNs 34442, 34461, 34471, 34475;
Vinko et al., GCN 34463; H. Kumar et al., GCN 34500; Turpin et al.,
GCN 34508) is clearly detected.
Preliminary photometry of the OT is following
Telescope Date UTstart Exptime Filter t-T0 OT Err UL
sec days
AZT-20 2023-08-17 16:51:34 60x60 r 4.932892 21.70 0.05 23.9
AZT-20 2023-08-17 18:14:50 60x60 i 4.990722 21.87 0.10 23.2
AZT-20 2023-08-18 16:47:02 60x60 r 5.929748 21.71 0.07 23.8
AZT-20 2023-08-18 18:05:43 60x60 i 5.984388 21.73 0.10 23.2
AZT-20 2023-08-20 16:15:33 60x60 r 7.907882 21.70 0.04 24.1
AZT-20 2023-08-20 17:37:12 60x60 i 7.964583 21.82 0.09 23.3
AZT-20 2023-08-21 16:31:06 60x60 r 8.918678 21.61 0.05 23.3
AZT-20 2023-08-21 17:51:59 80x60 i 8.981796 21.39 0.06 23.4
The photometry is based on nearby SDSS stars.
SDSS-DR12
RA Dec r i
16:36:25.6 +47:53:20.5 17.018 16.857
16:36:25.2 +47:52:20.9 16.229 16.106
After plateau phase between Aug. 15 - Aug.20 at r ~ 21.7, i~ 21.8 which is brighter than a host galaxy (e.g. Legacy Survey DR10 Catalog the host is r~22.66 (Belkin et al., GCN 34412)) the OT is brightening and we can confirm the OT brightening (Moskvitin et al., GCN 34516) which could be related with a supernova rise. The supernova rise have beed also suggested by GIT (GCN 34500).
GCN Circular 34526
Subject
GRB 230812B: AstroSat LAXPC detection
Date
2023-08-23T13:46:50Z (2 years ago)
From
Tilak Katoch at TIFR <tilak@tifr.res.in>
Via
legacy email
Tilak Katoch, H. M. Antia and Parag Shah TIFR, Mumbai, India.
AstroSat LAXPC data analysis revealed the presence of a strong short GRB 230812B. The GRB burst profile shows that it was triggered at T0 = 18h 58m 08s UT on 12 Aug 2023, when the satellite was in a normal operating mode and well before and after the SAA region.
The lightcurve obtained a burst profile with T90 = 4 sec. The strongest peak measured have a count rate 10678 +/- 105 count/sec in LAXPC10 above the background and 5069 +/- 73 count/sec in LAXPC20 at T0+2 sec.
Both LAXPC instruments (LAXPC10 and LAXPC20) have registered this burst profile in their respective lightcurves. LAXPC20 has a nominal energy range of 3-100 keV, but due to the lower gain in LAXPC10, the energy range is approximately 30-400 keV.
The background subtracted lightcurves of the LAXPC instruments with 0.2 sec time-bin is available at the website:
https://www.tifr.res.in/~astrosat_laxpc/grb230812lc.jpg
LAXPC was built by TIFR in collaboration with the Indian Space Research Organisation. The Indian Space Research Organisation funded, managed and facilitated the project.
GCN Circular 34552
Subject
GRB 230812B: radio detection with the VLA
Date
2023-08-25T18:17:37Z (2 years ago)
From
Stefano Giarratana at University of Bologna <s.giarratana@ira.inaf.it>
Via
email
S. Giarratana (University of Bologna, INAF-IRA), M. Giroletti
(INAF-IRA), G. Ghirlanda (INAF-OAB), N. Di Lalla (Stanford Univ.),
N. Omodei (Stanford Univ.)
At 01:52:24 UT on 2023 August 15 (T_mid = 2.3 days post-burst) the
Karl G. Jansky VLA observed the field of GRB 230812B (Fermi GBM
team, GCN 34386) at a central frequency of 6 and 10 GHz.
The standard J1331+3030 was used as bandpass and flux density
calibrator, while J1637+4717 was used as phase calibrator.
From a preliminary analysis, an unresolved radio source (Rhodes et al.,
GCN 34433; de Ugarte Postigo et al., GCN 34468) is clearly detected
at both frequencies at a position:
RA: 16:36:31.477 +- 0.001
Dec: +47:51:32.25 +- 0.02
The surface brightness peak is 230 uJy/beam and 196 uJy/beam at 6
and 10 GHz, respectively. The r.m.s. noise level of the images is
10 uJy/beam and 7 uJy/beam at 6 and 10 GHz, respectively.
The synthesized beams are 0.31 x 0.26 arcsec (PA: -45deg) at 6 GHz
and 0.20 x 0.16 arcsec (PA: -45deg) at 10 GHz.
We would like to thank the staff of the VLA for approving, executing,
and processing the observations.
The National Radio Astronomy Observatory is a facility of the National
Science Foundation operated under cooperative agreement by Associated
Universities, Inc.
These observations were carried out as part of project SF161095,
approved in the framework of the Fermi - NRAO joint program agreement.
GCN Circular 34597
Subject
GRB 230812B: Spectroscopic detection of the associated SN 2023pel.
Date
2023-08-29T22:49:42Z (2 years ago)
From
J. F. Agui Fernandez at IAA-CSIC <feli@iaa.es>
Via
email
J. F. Agui Fernandez (IAA-CSIC), A. de Ugarte Postigo (OCA-CNRS), C. C. Thoene (ASU-CAS), D. B. Malesani (Radboud and DAWN/NBI), L. Izzo (INAF-OACN and DARK/NBI) and A. L. Cabrera Lavers (GTC, IAC) report:
We observed the long GRB 230812B*/*SN 2023pel (Fermi GBM Team GCN, 34386; Roberts et al. GCN34391, Scotton et al. GCN 34392, Zheng & Filippenko GCN 34395, Beardmore et al. GCN 34400) on August 24, 2023 at 21.79 hours UT, ~12.12 days after the GRB detection, with OSIRIS+ in spectroscopy mode at the 10.4m GTC Telescope located at Roque de los Muchachos, Canary Islands, Spain. The spectrum covers the wavelength range from 3700 to 7500 AA. In a preliminary analysis, the spectrum shows the characteristic undulations of a GRB-SN spectrum. Our spectrum is well matched to the spectrum of SN 1998bw at a comparable rest-frame epoch (Patat et al. 2001, ApJ, 555, 900). We can thus conclusive determine the presence of a SN associated with GRB 230812B, confirming previous claims based on photometric evidence (Moskvitin & Spiridonova GCN 34475, Moskvitin & Goranskij GCN 34496, Kumar et al. GCN 34500, Turpin et al. GCN 34508, Kumar et al. GCN 34516, Pankov et al. GCN 34519).
We acknowledge excellent support from the GTC staff.
GCN Circular 34632
Subject
GRB 230812B: Chandra late-time detection of the X-ray afterglow
Date
2023-09-06T17:17:12Z (2 years ago)
From
Utkarsh Pathak at IIT Bombay <utkarshpathak.07@gmail.com>
Via
Web form
U. Pathak (IITB), A. Salgundi (IITB), G. Waratkar (IITB), V. Swain (IITB), V. Bhalerao (IITB), B. Cenko (UMD), G. Dewangan (IUCAA), T. Ahumada (UMD), I. Andreoni (UMCP), G C Anupama (IIA), D. Bhattacharya (IUCAA), A. Jaodand (CIT), M. Kasliwal (CIT), D. Perley (LJMU), G. Srinivasaragavan (UMCP), P. Chandra (NRAO) report on behalf of a larger collaboration
We carried out a Chandra DDT observation of GRB 230812B beginning on September 3, 2023, at 01:04:23 UT with ACIS-S as part of program 24408929 (PI: Pathak) for 21.39 ks. The observation began ~21.25 days after the GRB trigger.
Within the XRT localization (Page et al., GCN Circ. 34394), we detect a single point source at RA, DEC = 16:36:31.5221, 47:51:32.353 with an uncertainty of 0.4" from ZTF candidate afterglow (Salgundi et al., GCN Circ. 34397). The Chandra detection is consistent with decay rate as seen in XRT afterglow (Beardmore et al., GCN Circ. 34400) and the calculated absorbed flux for 0.3-10 keV is 7.33 (-1.35, +1.55) x 10^(-14) erg cm^-2 s^-1.
We thank the CXO staff - in particular Patrick Slane, Dan Schwartz, Harvey Tananbaum, Steiner James, Doug Swartz, and Malgorzata Sobolewska for rapidly approving and planning this observation.
GCN Circular 34694
Subject
GRB 230812B: Bad Time Intervals for Fermi GBM data
Date
2023-09-14T15:17:04Z (2 years ago)
From
Oliver J Roberts at USRA/NASA <oliver.roberts@nasa.gov>
Via
Web form
O.J. Roberts (USRA), S. Lesage (UAH) and W. Cleveland (USRA) report on behalf of the Fermi GBM Team:
"The Fermi Gamma-ray Burst Monitor data for GRB 230812B has a period of bad time intervals, affecting all data types and all detectors. At particularly high rates, the Time-Tagged Event (TTE) data has data-loss due to the bandwidth limit between the instrument and the spacecraft. CTIME and CSPEC data do not experience data-loss due to the electronics bandwidth, but do experience deadtime effects. Additionally, at particularly high rates both CTIME and CSPEC are affected by pulse pile-up, which will distort the spectra (see, S. Lesage et al., 2023, ApJL, 952, L42).
Due to the orientation of the burst, we recommend only using BGO detector: B0, and the NaI detectors: N0, N3, N6, N7 for any analysis of this burst, as all other detectors either have an unfavorable detector-source angle (>60 degrees), or are blocked by different parts of the spacecraft.
For CTIME and CSPEC data of these detectors, pulse pile-up occurs during the time intervals of T0+0.61 to T0+1.12 seconds for the BGO detector, B0. We find pulse pile-up occurs from T0+0.54 to T0+1.70 seconds for the NaI detectors N0, N3, N6, N7. T0 is the GBM trigger time.
In the TTE data, data losses due to the bandwidth limit being exceeded occurs between roughly T0+0.5 to T0+1.4 seconds. This region includes the artificially created pulse centered at roughly T0+1.233 seconds (width of approximately 0.098 seconds), that is due to TTE drop out. We are currently reprocessing the TTE files and will alert the community when these files become available in a forthcoming circular.
We recommend the exclusion of these time intervals for GBM analysis of this burst, as well as caution using bins adjacent to these selections."
GCN Circular 34727
Subject
GRB 230812B: Radio observations with the uGMRT
Date
2023-09-18T11:41:40Z (2 years ago)
From
S. Mohnani at Indian Institute Of Technology Indore <phd2201121011@iiti.ac.in>
Via
Web form
S. Mohnani (IIT Indore), S. Chatterjee (IIT Indore), B. Banerjee (GSSI), A. Shukla (IIT Indore), A. Datta (IIT Indore), G. Oganesyan (GSSI), S. Agarwal (IIT Indore), M. Branchesi (GSSI), K.K Yadav (ApSD BARC), V. Chitnis (TIFR), G.C. Anupama (IIA), P. Tiwari (GSSI), S. Mangla (IIT Indore)
At 11:30:00 UT on 2023 September 17 (35.92 days post-burst) upgraded Giant Meterwave Radio Telescope (uGMRT) observed the field of GRB 230812B (Fermi GBM team, GCN 34386) at a central frequency of 1.26 GHz for about 2 hours.
The standard 3C286 was used as a bandpass and flux density calibrator, while 1635+381 was used as a phase calibrator.
Based on preliminary analysis, we do not detect any source consistent with the location of the afterglow (A.P. Beardmore et al., GCN 34400; S. Giarratana et al., GCN 34552). The 3-sigma upper limit achieved is ~ 43 micro Jy.
We would like to thank the staff of the uGMRT for approving, executing,
and processing the observations through the DDT proposal (ddtC304; PI- Shraddha Mohnani).
The uGMRT is operated by the National Center for Radio Astrophysics of the Tata Institute of Fundamental Research.
GCN Circular 34735
Subject
Detection of self-absorbed radio emission from GRB 230812B with the JVLA + uGMRT
Date
2023-09-19T03:00:15Z (2 years ago)
From
pchandra@nrao.edu
Via
Web form
Poonam Chandra (NRAO), Tomas Ahumada (UMD), Varun Bhalerao (IITB), Gaurav Waratkar (IITB), Gokul Srinivasaragavan (UMD), Suchindram Dasgupta (Rutgers), Mansi Kasliwal (Caltech), Shreya Anand (Caltech), Viswajit Swain (IITB), David Kaplan (UWM), Harsh Kumar (IITB) and Daniel Perley (LJMU) report on behalf of a larger collaboration:
We observed GRB 230812B (Fermi GBM Team, GCN Circ. 34386) with Karl G. Jansky Very Large Array on Sep 2, 2023 during 18:24:52 - 19:53:33 UT (proposal # 23B-292) in X (8-12 GHz), C (4-8 GHz) and S (2-4 GHz) bands and with the upgraded Giant Metrewave Radio Telescope (uGMRT) on Sep 17, 2023, 11:30:00 UT (proposal # DDT C305) in band 5 (1000-1450 MHz). We detect the GRB in the three observed JVLA bands with S, C, X bands flux densities to be 30.6+/-11.2, 49.2+/-7.9 uJy and 28.2+/-10.1 uJy, respectively. The GRB is not detected in the uGMRT band 5 with a 3-sigma upper limit of ~40 uJy, consistent with the results of Mohnani et al., (GCN Circ. 34727). This indicates that the GRB is in the optically thin regime at C band and higher frequencies, however, it is self-absorbed at lower frequencies, i.e. JVLA S band and the uGMRT band 5.
We thank the VLA and GMRT staff for carrying out the observations. The National Radio Astronomy Observatory is a facility of the National Science Foundation operated under cooperative agreement by Associated Universities, Inc. GMRT is run by the National Centre for Radio Astrophysics of the Tata Institute of Fundamental Research. More observations are planned.
GCN Circular 34743
Subject
GRB 230812B : optical observations from MISTRAL at Observatoire de Haute-Provence
Date
2023-09-20T16:25:03Z (2 years ago)
From
christophe.adami@lam.fr
Via
Web form
C. Adami, P. Amram, S. Basa, K. Parra-Ramos (LAM), T. Adami (ENS Paris-Saclay), B. Schneider (MIT), A. Saccardi, S. D. Vergani, (GEPI, Obs. de Paris), S. Antier, A. de Ugarte Postigo (OCA),
E. Le Floc'h, D. Götz, F. Schüssler, D. Turpin (CEA-Saclay), report, on behalf of a larger collaboration:
We observed the field of GRB 230812B (Fermi GBM Team GCN, 34386 and all subsequent GCNs) using the MISTRAL spectro-imager of Observatoire de Haute Provence (OHP) in imaging mode. We obtained
during the 2023 09 17 night 1x1200s exposure in the r'-band with a mid-epoch of 19:20 UT, during the 2023 09 18 night 1x600s and 2x900s exposures in the r'-band with a mid-epoch of 21:06 UT, and during the 2023 09 19
night 8x600sec and 1x700sec in the r'-band with a mid epoch of 19:58 UT.
We derive the following photometry, calibrated against the Pan-STARRS catalog, not corrected for the underlying galaxy, and not corrected for Galactic dust reddening:
2023 09 17 19:20 UT r' = 22.36 +/- 0.16
2023 09 18 21:06 UT r' = 22.37 +/- 0.14
2023 09 19 19:58 UT r' = 22.45 +/- 0.10
We acknowledge the excellent support from Jerome Schmitt, Stephane Favard and Jean Balcaen (Observatoire de Haute Provence).
GCN Circular 34762
Subject
GRB 230812B: r'-band observations from MISTRAL at Observatoire de Haute-Provence
Date
2023-09-24T19:28:39Z (2 years ago)
From
Christophe Adami at LAM <christophe.adami@lam.fr>
Via
Web form
P. Amram, C. Adami, S. Basa (LAM/Pythéas), T. Adami (ENS Paris-Saclay), B.
Schneider (MIT), A. Saccardi, S. D. Vergani, (GEPI, Obs. de Paris), S.
Antier, A. de Ugarte Postigo (OCA), E. Le Floc'h, D. Götz, F. Schüssler,
D. Turpin (CEA-Saclay), report, on behalf of a larger collaboration:
We observed the field of GRB 230812B (Fermi GBM Team GCN, 34386 and all
subsequent GCNs) using the MISTRAL spectro-imager of Observatoire de Haute
Provence (OHP) in imaging mode. We obtained during the 2023 09 22 night 12x600s
exposure in the r'-band with a mid-epoch of 20:30 UT.
We derive the following photometry, calibrated against the Pan-STARRS catalog,
not corrected for the underlying galaxy, and not corrected for Galactic dust reddening:
2023 09 22 20:30 UT r' = 22.37 +/- 0.14
We acknowledge the excellent support from Yoann Degot-Longhi (Observatoire de Haute
Provence) and we thank Isabelle Boisse.
GCN Circular 35505
Subject
GRB 230812B: further radio observations with the VLA
Date
2024-01-09T13:22:01Z (a year ago)
From
Stefano Giarratana at University of Bologna <s.giarratana@ira.inaf.it>
Via
email
S. Giarratana (University of Bologna, INAF-IRA), M. Giroletti
(INAF-IRA), G. Ghirlanda (INAF-OAB), N. Di Lalla (Stanford Univ.),
N. Omodei (Stanford Univ.)
At 18:39:38 UT on 2023 August 29 (T_mid = 17.0 days post-burst)
and at 17:37:02 UT on 2023 September 19 (T_mid = 38.0 days
post-burst) the Karl G. Jansky VLA started observing the field of
GRB 230812B (Fermi GBM team, GCN 34386) at a central
frequency of 6 and 10 GHz.
The standard J1331+3030 (3C286) was used as bandpass and
flux density calibrator, while J1637+4717 was used as complex
gain calibrator.
From a preliminary analysis, the radio counterpart of GRB 230812B
(Rhodes et al., GCN 34433; de Ugarte Postigo et al., GCN 34468;
Giarratana et al., GCN 34552; Chandra et al., GCN 34735) is no
longer detected. We derive the following upper limits (UL; 3sigma).
=====================================================
T_mid Freq UL r.m.s. Beam PA
[days] [GHz] [uJy] [uJy/b] [arcsec] [deg]
=====================================================
17.0 6 24 8 0.68x0.29 -71
17.0 10 24 8 0.50x0.18 -65
38.0 6 21 7 0.60x0.29 -74
38.0 10 21 7 0.40x0.18 -70
=====================================================
We note that the 6 GHz upper limit at 17 days post-burst seems
inconsistent with the detection reported by Chandra et al., GCN 34735,
at the same frequency.
We would like to thank the staff of the VLA for approving, executing,
and processing the observations.
The National Radio Astronomy Observatory is a facility of the National
Science Foundation operated under cooperative agreement by Associated
Universities, Inc.
These observations were carried out as part of project SF161095,
approved in the framework of the Fermi - NRAO joint program agreement.
GCN Circular 35660
Subject
GRB 230812B: Update on Bad Time Intervals for Fermi GBM data
Date
2024-02-02T20:44:59Z (a year ago)
From
Oliver J Roberts at USRA/NASA <oliver.roberts@nasa.gov>
Via
Web form
O.J. Roberts (USRA) and W. Cleveland (USRA) report on behalf of the Fermi GBM Team:
"The Fermi Gamma-ray Burst Monitor data for GRB 230812B had a bad time interval affecting all data types and all detectors, which was reported in GCN #34694. Subsequently, we reprocessed the TTE data in an effort to remove spurious artefacts, such as the artificially created pulse centered at roughly T0+1.233 seconds due to TTE drop out. We encourage those in the community interested in analyzing this event, to use the v4 TTE trigger data found on the GBM HEASARC page: https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2023/bn230812790/current/
We note, that while we have tried to reprocess the data for this trigger to the best of our ability, pulse pile-up and deadtime effects still remain in all detectors and data types from roughly T0+0.5 to T0+1.4 seconds. We again, recommend the exclusion of these time intervals for GBM analysis of this burst, as well as caution using bins adjacent to these selections."