GRB 230816A
GCN Circular 34474
Subject
GRB 230816A: Swift-BAT refined analysis
Date
2023-08-18T18:04:02Z (2 years ago)
From
Tyler Parsotan at NASA GSFC <tyler.parsotan@nasa.gov>
Via
email
A. Y. Lien (U Tampa), S. D. Barthelmy (GSFC),
H. A. Krimm (NSF), S. Laha (GSFC/UMBC),
C. B. Markwardt (GSFC), D. M. Palmer (LANL),
T. Parsotan (GSFC/UMBC), T. Sakamoto (AGU),
M. Stamatikos (OSU) (i.e. the Swift-BAT team):
Using the data set from T-239 to T+303 sec from the recent telemetry downlink,
we report further analysis of BAT GRB 230816A (trigger #1185673)
(Siegel, et al., GCN Circ. 34450). The BAT ground-calculated position is
RA, Dec = 328.453, 37.853 deg which is
RA(J2000) = 21h 53m 48.8s
Dec(J2000) = +37d 51' 12.1"
with an uncertainty of 1.2 arcmin, (radius, sys+stat, 90% containment).
The partial coding was 98%.
The mask weighted light curve shows a fast rise exponential decay type single peak.
T90 (15-350 keV) is 20.48 +- 4.94 sec (estimated error including systematics).
The time-averaged spectrum from T-5.60 to T+21.08 sec is best fit by a simple
power-law model. The power law index of the time-averaged spectrum is
1.43 +- 0.14. The fluence in the 15-150 keV band is 7.7 +- 0.7 x 10^-07 erg/cm2.
The 1-sec peak photon flux measured from T+0.60 sec in the 15-150 keV band
is 1.0 +- 0.1 ph/cm2/sec. All the quoted errors are at the 90% confidence
level.
The results of the batgrbproduct analysis are available at
http://gcn.gsfc.nasa.gov/notices_s/1185673/BA/ <http://gcn.gsfc.nasa.gov/notices_s/1185673/BA/>
GCN Circular 34473
Subject
GRB 230816A: SVOM/C-GFT optical detection
Date
2023-08-18T13:41:54Z (2 years ago)
From
Chao Wu at NAOC <wuchao.lamost@gmail.com>
Via
legacy email
Liping Xin (NAOC), Chao Wu (NAOC), Zhe Kang (CHO), Xuhui Han (NAOC), Huali
Li (NAOC), Xiaomeng Lu (NAOC), Damien Turpin(CEA), Zhenwei Li
(CHO)，Pinpin Zhang (NAOC)，Ruosong Zhang (NAOC)，Yulei Qiu (NAOC)，You Lv
(CHO)，Jing Wang(GXU), Cordier Bertrand (CEA) and Jianyan Wei (NAOC) on
behalf of SVOM GRB team
We observed the burst GRB230816A (Siegel et al. GCN Circ. 34450) on
16:15:38 UT, Aug. 16th, 2023, about 6.9 minutes after the Swift trigger
with C-GFT (Chinese Ground Follow-up Telescope in SVOM mission) in System
Test Mode (STM). C-GFT is located at Jilin (long.=126.33 deg,
lat.=43.8243778 deg), Changchun Observatory, National Astronomical
Observatories, CAS. It has FOV of 1.5 deg X 1.5 deg with a 4k*4k CMOS
detector mounted on the primary focus of 1.2-meter-aperure telescope.
A series of g and r band images were obtained. The exposure time was 10
seconds for each frame.
The optical afterglow reported (Jiang et al., GCN 34453, Moskvitin et al.,
GCN 34456., Pankov et al.,GCN 34457, Odeh et al., GCN 34458Klose et al.,
GCN 34459., Kumar et al., GCN 34460; Ruocco et al., GCN 34469) was also
clearly detected by our stacked r-band image (100 * 10 seconds). The
brightness was estimated to be about 20.1 +/-0.2 magnitude in r-band with
the midtime of about 34 min after the burst, after calibration with nearby
USNO R2 catalogs.
More detailed analysis is continuing.
We thank the observation assistant Bowen Li at Jilin observatory for their
excellent support.
This message may be cited.
GCN Circular 34470
Subject
GRB 230816A: Swift-XRT refined Analysis
Date
2023-08-17T21:21:12Z (2 years ago)
From
Phil Evans at U of Leicester <pae9@star.le.ac.uk>
Via
email
M.G. Bernardini (INAF-OAB), J. D. Gropp (PSU), S. Dichiara (PSU), J.A.
Kennea (PSU), K.L. Page (U. Leicester), A.P. Beardmore (U. Leicester),
E. Ambrosi (INAF-IASFPA) , M. Capalbi (INAF-IASFPA) and P.A. Evans
report on behalf of the Swift-XRT team:
We have analysed 3.9 ks of XRT data for GRB 230816A, from 97 s to 91.3
ks after the BAT trigger. The data are entirely in Photon Counting
(PC) mode.
The light curve can be modelled with a power-law decay with a decay
index of alpha=1.44 (+0.27, -0.43).
A spectrum formed from the PC mode data can be fitted with an absorbed
power-law with a photon spectral index of 1.66 (+0.31, -0.14). The
best-fitting absorption column is consistent with the Galactic value
of 2.9 x 10^21 cm^-2 (Willingale et al. 2013). The counts to observed
(unabsorbed) 0.3-10 keV flux conversion factor deduced from this
spectrum is 4.4 x 10^-11 (5.6 x 10^-11) erg cm^-2 count^-1.
A summary of the PC-mode spectrum is thus:
Total column: 2.9 (+/-1.2) x 10^21 cm^-2
Galactic foreground: 2.9 x 10^21 cm^-2
Excess significance: <1.6 sigma
Photon index: 1.66 (+0.31, -0.14)
The results of the XRT-team automatic analysis are available at
http://www.swift.ac.uk/xrt_products/01185673.
This circular is an official product of the Swift-XRT team.
GCN Circular 34469
Subject
GRB 230816A: Osservatorio Astronomico "Nastro Verde" optical observations
Date
2023-08-17T19:51:04Z (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 230816A (Siegel et al., GCN 34450) 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 18:55 UT of 2023/08/16, after about 2,45 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 25 image of 240 sec each. All images are unfiltered, calibrated with masterdark and masterflat,stacked with Tycho Tracker software
We have detected a faint source of magnitude 19.1 G at the enhanced position reported by Swift-XRT (Siegel et al., GCN 34450, P.A. Evans et al., GCN 34462) and by optical telescopes ( A. S. Moskvitin et al GCN 34456., N. Pankov et al GCN 34457., Mohammad Odeh et al GCN 34458., S. Klose et al GCN 34459., R. Kumar et al GCN 34460)
at following position
RA (J2000.0) 21h 53m 46.87s
Decl. (J2000.0) +37° 51' 14.7"
Photometry and astrometry on stack of 13 images each of 240 sec
GRB 230816A KC2023 08 16.88481 21 53 46.87 +37 51 14.7 19.1 G C82
Magnitudes were estimated with the GAIA DR2 cat. and
are not corrected for galactic dust extinction.
The message may be cited.
GCN Circular 34462
Subject
GRB 230816A: Enhanced Swift-XRT position
Date
2023-08-17T03:20:23Z (2 years ago)
From
Phil Evans at U of Leicester <pae9@star.le.ac.uk>
Via
email
P.A. Evans, M.R. Goad, J.P. Osborne and A.P. Beardmore (U. Leicester)
report on behalf of the Swift-XRT team.
Using 1206 s of XRT Photon Counting mode data and 1 UVOT
images for GRB 230816A, we find an astrometrically corrected X-ray
position (using the XRT-UVOT alignment and matching UVOT field sources
to the USNO-B1 catalogue): RA, Dec = 328.44568, +37.85495 which is equivalent
to:
RA (J2000): 21h 53m 46.96s
Dec (J2000): +37d 51' 17.8"
with an uncertainty of 2.3 arcsec (radius, 90% confidence).
This position may be improved as more data are received. The latest
position can be viewed at http://www.swift.ac.uk/xrt_positions. Position
enhancement is described by Goad et al. (2007, A&A, 476, 1401) and Evans
et al. (2009, MNRAS, 397, 1177).
This circular was automatically generated, and is an official product of the
Swift-XRT team.
GCN Circular 34460
Subject
GRB230816A: Possible host and GIT detection of optical counterpart
Date
2023-08-16T22:08:37Z (2 years ago)
From
Vishwajeet Swain at IIT Bombay <vishwajeet.s@iitb.ac.in>
Via
Web form
R. Kumar (IITB), R. Sharma (IITB), V. Swain (IITB), A. Salgundi (IITB), H. Kumar (IITB), G. Waratkar(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 GRB 230816A detected by SWIFT (Siegel et al., GCN 34450) with 0.7m GROWTH-India Telescope (GIT). We started observations at 16:40:00 UT, i.e., 31.2 mins after the Swift/BAT trigger. We obtained 5 frames in the r' band of 300 sec each. After image subtraction, we detected a source in our stacked image at RA 21:53:46.96, Dec: +37:51:16.08 with an uncertainty of 0.67 arcsec - coincident with the reported afterglow (Jiang et al., GCN 34453), and 3.75 arsec away from center of the XRT error circle (Siegel et al., GCN 34450).
We note that there is a faint source (m_r ~ 23.0) nearly coincident with the counterpart in the Pan-STARRS1 images, which could be a host of this GRB. Our image subtraction ensures that this source flux does not affect out photometric measurements. There is no minor planet present at this position. The photometric results are as follows:
----------------------------------------------------------------------
JD (mid) | T_mid-T0 (mins) | Exposure (sec) | Filter | Magnitude (AB) |
----------------------------------------------------------------------
2460173.202193 | 42.35 | 5 x 300 | r' | 20.61 +/- 0.06 |
----------------------------------------------------------------------
Our results are consistent with other reports (Jiang et al. GCN 34453, Moskvitin et al., GCN 34456, Pankov et al., GCN 34457, Odeh et al., GCN 34458, Klose et al., GCN 34459). We encourage photometric for further confirmation and spectroscopic follow-up for redshift measurement. The magnitudes are calibrated against PanSTARRS DR1 (Chambers et al., 2016) and are not corrected for Galactic extinction.
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 34459
Subject
GRB 230816A: Tautenburg observations
Date
2023-08-16T21:06:26Z (2 years ago)
From
Sylvio Klose at TLS Tautenburg <klose@tls-tautenburg.de>
Via
email
S. Klose, S. Melnikov, B. Stecklum, A. Nicuesa Guelbenzu, F. Ludwig (all TLS Tautenburg) report:
We observed the field of GRB 230816A (Siegel et al., GCN 34450) with the Tautenburg 1.34m Schmidt telescope equipped with the TAUKAM 6kx6k CCD camera and using the Sloan filter set.
For the optical transient discovered by Jiang et al. (GCN 34453) we measure the following preliminary magnitudes:
r = 21.75 +/- 0.25 (midtime: August 16, 2023, 20:23:11 UT),
i = 20.33 +/- 0.08 (midtime: August 16, 2023, 20:34:05 UT),
calibrated against USNO stars in the field. The photometry will still be improved by calibrating the data via a nearby Pan-STARRS field.
GCN Circular 34458
Subject
GRB 230816A: AKO Optical Observations
Date
2023-08-16T20:58:15Z (2 years ago)
From
Mohammad Odeh at Al Khatim Observatory M44 <mshodeh@gmail.com>
Via
legacy email
Mohammad Odeh, Nada Odeh, Osama Ghannam, Anas Mohammad, and Khalfan
Al-Noaimy, report on behalf of Al-Khatim Observatory (AKO) operated by the
International Astronomical Center in Abu Dhabi, UAE:
We observed the field of the GRB 230816A (Siegel et al., GCN 34450) with
our 0.36m f/7.7 robotic telescope. We obtained 21 x 180 sec. images in a
clear filter on 16 August, from 19:05 to 20:36 UT.
We detected the afterglow (Jiang et al., GCN 34453; Moskivitin et al., GCN
34456; Pankov et al., GCN 34457) in our stacked images with the coordinates
(J2000) R.A.= 21:53:47.01, Dec.= +37:51:16.7 and the brightness of Mv =
20.6 +/- 0.27 (t_mid - t0 = 3.7 hours).
The magnitude is not corrected for galactic extinction.
GCN Circular 34457
Subject
GRB 230816A: TShAO and Assy optical observations
Date
2023-08-16T20:29:24Z (2 years ago)
From
Alexei Pozanenko at IKI, Moscow <apozanen@iki.rssi.ru>
Via
legacy email
N. Pankov (HSE, IKI), I. Reva (FAI), V. Kim (FAI), A. Pozanenko (IKI), S. Belkin (IKI) report on behalf of the GRB-IKI-FuN.
We observed the field of the GRB 230816A (Siegel et al., GCN 34450)
with Zeiss-1000 telescope of Tien-Shan Observatory (TShAO) and AZT-20 telescope of Assy Observatory. We clearly detect the afterglow (Jiang et al., GCN 34453; Moskivitin et al., GCN 34456) in the stacked images.
Preliminary photometry is following
Date UT start t-T0 Filter Exp. OT Err. UL(3sigma)
(mid, days) (s)
2023-08-16 16:21:24 0.034787 R 25*180 19.57 0.10 22.3
2023-08-16 17:26:29 0.072354 r' 53*60 21.10| 0.025 23.5
The photometry is based on nearby stars of USNO-B1.0 and PanSTARRS-DR1 catalogues.
RA Dec R2 r'
328.5043802 +37.8674441 16.47 16.8245
328.3579777 +37.8706420 17.04 17.1589
328.4483771 +37.8290610 15.45 15.3054
GCN Circular 34456
Subject
GRB 230816A: SAO RAS optical observations
Date
2023-08-16T19:26:01Z (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 the GRB 230816A (Siegelet al., GCN 34450)
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 August 16,
17:45:41 -- 18:35:29 UT.
The OT (Jiang et al., GCN 34453) is clearly detected in our stacked
frame with the coordinates
R.A. (J2000) = 21:53:46.9,
Decl.(J2000) = +37:51:16.7 (+/- 0".5)
and the brightness of R = 21.0 +/- 0.1 (t_mid - t0 = 2.030h = 0.0846d).
This preliminary photometry is based on nearby USNO-B1 stars (R2 mag),
the magnitude is not corrected for MW extinction.
GCN Circular 34453
Subject
GRB 230816A: Nanshan/HMT optical afterglow detection
Date
2023-08-16T18:15:50Z (2 years ago)
From
Dong Xu at NAOC/CAS <dxu@nao.cas.cn>
Via
email
S.Q. Jiang, S.Y. Fu, X. Liu, T.H. Lu, Z.P. Zhu, D. Xu (NAOC), X. Gao (Urumqi No.1 Senior High School), J.Z. Liu (XAO) report:
We observed the field of GRB 230816A detected by Swift (Siegel et al., GCN 34450) using the HMT-0.5m telescope located at Nanshan, Xinjiang, China. Observations started at 16:10:20 UT on 2023-08-16, i.e., 92 s after the Swift/BAT trigger, we obtained a serise of 3x20, 3x40, 4x60, 12x90 s frames without any filter.
An uncatalogued optical source is detected in our stacked image at coordinates
R.A. (J2000) = 21:53:46.9
Dec. (J2000) = +37:51:15.9
2.23 arcsec away from the center of the XRT error circle (radius: 1.9 arcsec, 90% containment; Siegel et al., GCN 34450) with m(r) = 19.6 +/- 0.18 mag(AB) at 24.6 min post-burst, calibrated with the nearby PanSTAR field in the Sloan r-filter and the magnitude is not corrected for Galactic extinction. We thus think this OT is the optical afterglow of the burst.
GCN Circular 34450
Subject
GRB 230816A: Swift detection of a burst
Date
2023-08-16T16:24:41Z (2 years ago)
From
David Palmer at LANL <palmer@lanl.gov>
Via
email
M. H. Siegel (PSU), S. Dichiara (PSU),
R. A. J. Eyles-Ferris (U Leicester), J.D. Gropp (PSU),
J. A. Kennea (PSU), F. E. Marshall (NASA/GSFC), M. J. Moss (GWU),
K. L. Page (U Leicester), D. M. Palmer (LANL),
T. M. Parsotan (GSFC/UMBC/CRESSTII), B. Sbarufatti (INAF-OAB) and
M. A. Williams (PSU) report on behalf of the Neil Gehrels Swift
Observatory Team:
At 16:08:48 UT, the Swift Burst Alert Telescope (BAT) triggered and
located GRB 230816A (trigger=1185673). Swift slewed immediately to the burst.
The BAT on-board calculated location is
RA, Dec 328.375, +37.828 which is
RA(J2000) = 21h 53m 30s
Dec(J2000) = +37d 49' 43"
with an uncertainty of 3 arcmin (radius, 90% containment, including
systematic uncertainty). The BAT light curve showed a single-peaked
structure with a duration of about 25 sec. The peak count rate
was ~1900 counts/sec (15-350 keV), at ~0 sec after the trigger.
The XRT began observing the field at 16:10:18.4 UT, 90.2 seconds after
the BAT trigger. Using promptly downlinked data we find a fading,
uncatalogued X-ray source with an enhanced position: RA, Dec 328.44552,
37.85549 which is equivalent to:
RA(J2000) = 21h 53m 46.92s
Dec(J2000) = +37d 51' 19.8"
with an uncertainty of 1.9 arcseconds (radius, 90% containment). This
location is 223 arcseconds from the BAT onboard position. This position
may be improved as more data are received; the latest position is
available at https://www.swift.ac.uk/sper.
A power-law fit to a spectrum formed from promptly downlinked event
data gives a column density in excess of the Galactic value (2.90 x
10^21 cm^-2, Willingale et al. 2013), with an excess column of 3.7
(+3.48/-2.91) x 10^21 cm^-2 (90% confidence).
UVOT took a finding chart exposure of 150 seconds with the White filter
starting 93 seconds after the BAT trigger. No credible afterglow candidate has
been found in the initial data products. The 2.7'x2.7' sub-image covers none of
the XRT error circle. The 8'x8' region for the list of sources generated
on-board covers 100% of the XRT error circle. The list of sources is typically
complete to about 18 mag. No correction has been made for the expected
extinction corresponding to E(B-V) of 0.311.
Burst Advocate for this burst is M. H. Siegel (siegel AT swift.psu.edu).
Please contact the BA by email if you require additional information
regarding Swift followup of this burst. In extremely urgent cases, after
trying the Burst Advocate, you can contact the Swift PI by phone (see
Swift TOO web site for information: http://www.swift.psu.edu/)