GRB 230723A
GCN Circular 34309
Subject
GRB 230723A: SPT-3G millimeter-band transient event inconsistent with IPN position
Date
2023-08-01T20:16:17Z (2 years ago)
From
Sam Guns at S Pole Telescope & UC Berkeley <sguns@berkeley.edu>
Via
Web form
S. Guns (UC Berkeley) on behalf of the South Pole Telescope Collaboration:
In light of the updated error box provided by IPN, the millimeter-band transient event reported by the South Pole Telescope in GCN #34301 is no longer spatially consistent with GRB 230723A (Fermi GBM, GCN #34232; IPN, GCN #34258). The event remains an unexplained, short-duration millimeter-band transient not obviously associated with any known galactic source.
GCN Circular 34301
Subject
GRB 230723A: Detection of candidate millimeter-band radiation by SPT-3G
Date
2023-07-31T19:40:10Z (2 years ago)
From
Sam Guns at S Pole Telescope & UC Berkeley <sguns@berkeley.edu>
Via
Web form
S. Guns (UC Berkeley), A. Foster (CWRU), C. Tandoi (UIUC), K. Phadke (UIUC), N. Whitehorn (MSU), G. Holder (UIUC), J. Vieira (UIUC) on behalf of the South Pole Telescope Collaboration:
On 26 July 2023 at 16:48 UTC the South Pole Telescope detected a millimeter-band transient candidate at RA = 43.5275, Dec = -70.4770 (J2000 degrees, uncertainty 12 arcseconds) using the SPT-3G camera in 2 bands centered at 95 GHz and 150 GHz. Peak emission was observed two hours later at 19:14 UTC with flux levels of 18.5 mJy in both bands, after which the SPT slewed away from the observing field. The next series of observations on 28 July showed flux levels consistent with zero. The spatial location of the emission is consistent (1.5 sigma) with GRB 230723A which was detected by Fermi-GBM on 23 July 2023 at RA = 21.0, Dec = -71.2 (J2000 degrees, uncertainty 4.8 degrees). From the SPT-3G transients program, short duration (<1 week) millimeter-band transients that are not associated with nearby stars are rare (<3 events per year). A table of SPT-3G observations is given below.
The lightcurve can be found at:
https://pole.uchicago.edu/public/data/transients/lightcurves/SPT-SVJ025406.5-702837.png
Observation time | Flux (95 GHz) | Error (95 GHz) | Flux (150 GHz) | Error (150 GHz)
2023-7-22 05:04 UTC | -3.0 mJy | 2.5 mJy | -3.3 mJy | 3.0 mJy
2023-7-26 16:48 UTC | 13.3 mJy | 4.4 mJy | 14.0 mJy | 4.9 mJy
2023-7-26 19:14 UTC | 18.5 mJy | 4.4 mJy | 18.5 mJy | 4.9 mJy
2023-7-28 08:12 UTC | 1.7 mJy | 2.5 mJy | 1.8 mJy | 2.8 mJy
The South Pole Telescope is a 10-meter telescope located at Amundsen-Scott South Pole Station and supported by the National Science Foundation and the US Dept. of Energy. The SPT online transient program providing data in this circular is supported by NSF grants AST-1716965 and OPP 1852617, and observes 1500 square degrees of the southern sky at 95, 150, and 220 GHz with an average revisit cadence of 12 hours. For more details on the SPT transient program and survey strategy, please see https://arxiv.org/abs/2103.06166.
GCN Circular 34269
Subject
Konus-Wind detection of GRB 230723A
Date
2023-07-26T15:06:31Z (2 years ago)
From
Anna Ridnaia at Ioffe Institute <ridnaia@mail.ioffe.ru>
Via
Web form
A.Ridnaia, D. Frederiks, A.Lysenko, D. Svinkin,
A. Tsvetkova, M. Ulanov, and T. Cline,
on behalf of the Konus-Wind team, report:
The short-duration GRB 230723A
(Fermi GBM detection: The Fermi GBM team, GCN 34232;
AGILE/MCAL detection: Panebianco et al., GCN 34237;
IPN triangulation: Kozyrev et al., GCN 34258)
triggered Konus-Wind at T0=16725.802 s UT (04:38:45.802).
The burst light curve shows a multipeaked structure,
which starts at T0-0.346 s and has a total duration of ~0.62 s.
The Konus-Wind light curve of this GRB is available at
http://www.ioffe.ru/LEA/GRBs/GRB230723_T16725/
As observed by Konus-Wind, the burst
had a fluence of 1.66(-0.06,+0.54)x10^-6 erg/cm2,
and a 16-ms peak flux, measured from T0-0.220 s,
of 8.56(-1.76,+3.29)x10^-6 erg/cm2/s
(both in the 20 keV - 10 MeV energy range).
Since the main fraction of the burst emission was detected
before the trigger, the spectral analysis was performed using
the KW 3-channel light curve data.
Modelling the KW 3-channel time-integrated spectrum
(measured from T0-0.346 s to T0+0.620 s)
by a power law with exponential cutoff model:
dN/dE ~ (E^alpha)*exp(-E*(2+alpha)/Ep),
yields alpha = -0.21(-0.26,+0.27) and Ep = 659(-99,+162) keV.
All the quoted errors are at the 68% confidence level.
All the quoted values are preliminary.
GCN Circular 34258
Subject
IPN triangulation of GRB 230723A (short)
Date
2023-07-25T15:40:41Z (2 years ago)
From
Anna Ridnaia at Ioffe Institute <ridnaia@mail.ioffe.ru>
A.S. Kozyrev, D.V. Golovin, M.L. Litvak, I.G. Mitrofanov, and A.B. Sanin
on behalf of the HEND/Mars Odyssey team,
A. Ridnaia, D. Frederiks, D. Svinkin, A. Lysenko,
and T. Cline on behalf of the Konus-Wind team,
A. Goldstein, M. S. Briggs, C. Wilson-Hodge,
and E. Burns on behalf of the Fermi GBM team,
and
W. Boynton, C. Fellows, K. Harshman, H. Enos, R. Starr,
and A.S. Gardner on on behalf of the GRS-Odyssey GRB team,
report:
The short-duration GRB 230723A
(Fermi GBM detection: The Fermi GBM team, GCN 34232;
AGILE/MCAL detection: Panebianco et al., GCN 34237)
has been detected by Fermi (GBM), Konus-Wind,
AGILE (MCAL, AC), and Mars-Odyssey (HEND), so far,
at about 16723 s UT (04:38:43).
We have triangulated it to a preliminary, 3 sigma error box
whose coordinates are:
---------------------------------------------
RA(2000), deg Dec(2000), deg
---------------------------------------------
Center:
22.909 (01h 31m 38s) -67.059 (-67d 03' 31")
Corners:
24.618 (01h 38m 28s) -66.230 (-66d 13' 48")
24.638 (01h 38m 33s) -66.276 (-66d 16' 34")
21.066 (01h 24m 16s) -67.859 (-67d 51' 31")
21.054 (01h 24m 13s) -67.813 (-67d 48' 46")
---------------------------------------------
The error box area is 265 sq. arcmin, and its maximum
dimension is 2.1 deg (the minimum one is 2 arcmin).
The Sun distance was 111 deg.
The IPN localization is consistent with, but reduces
the area of, the Fermi-GBM final localization (GCN 34232).
This localization may be improved.
A triangulation map and HEALPix FITS file are posted at
http://www.ioffe.ru/LEA/GRBs/GRB230723_T16725/IPN/
The Konus-Wind time history and spectrum will be given
in a forthcoming GCN Circular.
GCN Circular 34237
Subject
GRB 230723A: AGILE/MCAL detection
Date
2023-07-23T15:01:44Z (2 years ago)
From
Gabriele Panebianco <gabriele.panebianco@inaf.it>
G. Panebianco (Univ. Bologna - INAF/OAS Bologna), C. Casentini (INAF/IAPS), F. Verrecchia,
C. Pittori (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, 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), F. Longo (Univ. Trieste and INFN Trieste),
I. Donnarumma, E. Menegoni (ASI), A. Giuliani (INAF/IASF-Mi), P. 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 230723A at T0 = 2023-07-23 04:38:43 s (UTC),
reported by Fermi GBM and Global MASTER-Net (GCNs #34232, #34233).
The burst is clearly visible in the AGILE scientific ratemeters of the
MiniCALorimeter (MCAL; 0.4-100 MeV), and AntiCoincidence (AC; 50-200 keV) detectors.
The event lasted about 4 s and it released a total number
of 3239 counts in the MCAL detector (above a background rate of 499 Hz)
and 16051 counts in the AC-Top detector (above a background rate of 2505 Hz).
The AGILE ratemeters light curves can be found at
http://www.agilescienceapp.it/notices/GRB230723A_AGILE_RM_ND.png .
The event also triggered a high time resolution MCAL data acquisition,
from T0-5.0 s to T0+8.6 s (UTC), and released 1186 counts in the detector, above
a background rate of 449 Hz.
The MCAL light curve can be found
at http://www.agilescienceapp.it/notices/GRB230723A_084565_617171923.000000.png .
The time-integrated spectrum of the burst between T0 and T0+2s be fitted in the
energy range 0.4-10 MeV with a power-law with ph. ind. = -1.8 +/- 0.3,
resulting in a reduced chi-squared of 0.94 (48 d.o.f.) and a fluence of 2.5e-06
ergs/cm^2 (90% confidence level), in the same energy range.
At the T0, the event was 103 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 34233
Subject
Fermi GRB 230723A: Global MASTER-Net observations report
Date
2023-07-23T06:16:32Z (2 years ago)
From
Vladimir Lipunov at Moscow State U/Krylov Obs <lipunov@xray.sai.msu.ru>
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-OAFA robotic telescope (Global MASTER-Net: http://observ.pereplet.ru, Lipunov et al., 2010, Advances in Astronomy, vol. 2010, 30L) located in Argentina (OAFA observatory of San Juan National University) started inspect of the Fermi GRB 230723A ( Fermi GBM team, GCN 34232) errorbox 552 sec after notice time and 586 sec after trigger time at 2023-07-23 04:48:29 UT, with upper limit up to 17.0 mag. The observations began at zenith distance = 57 deg. The sun altitude is -79.1 deg.
The galactic latitude b = -46 deg., longitude l = 299 deg.
Real time updated cover map and OT discovered available here:
https://master.sai.msu.ru/site/master2/observ.php?id=2243548
We obtain a following upper limits.
Tmid-T0 | Date Time | Site | Coord (J2000) |Filt.| Expt. | Limit| Comment
_________|_____________________|_____________________|____________________________________|_____|_______|_______|________
646 | 2023-07-23 04:48:29 | MASTER-OAFA | (01h 22m 59.72s , -71d 17m 29.3s) | C | 120 | 15.9 |
801 | 2023-07-23 04:48:29 | MASTER-OAFA | (01h 22m 59.76s , -71d 17m 29.2s) | C | 430 | 17.0 | Coadd
795 | 2023-07-23 04:50:48 | MASTER-OAFA | (01h 22m 53.01s , -71d 18m 28.8s) | C | 140 | 16.5 |
970 | 2023-07-23 04:53:28 | MASTER-OAFA | (01h 22m 54.39s , -71d 17m 31.5s) | C | 170 | 16.7 |
1165 | 2023-07-23 04:56:38 | MASTER-OAFA | (01h 23m 00.17s , -71d 18m 30.9s) | C | 180 | 15.6 |
Filter C is a clear (unfiltred) band.
The observation and reduction will continue.
The message may be cited.
GCN Circular 34232
Subject
GRB 230723A: Fermi GBM Final Real-time Localization
Date
2023-07-23T04:49:14Z (2 years ago)
From
Fermi GBM Team at MSFC/Fermi-GBM <do_not_reply@GIOC.nsstc.nasa.gov>
The Fermi GBM team reports the detection of a likely SHORT GRB
At 04:38:43 UT on 23 Jul 2023, the Fermi Gamma-ray Burst Monitor (GBM) triggered and located GRB 230723A (trigger 711779928.466758 / 230723194).
The on-ground calculated location, using the Fermi GBM trigger data, is RA = 21.0, Dec = -71.2 (J2000 degrees, equivalent to J2000 01h 23m, -71d 12'), with a statistical uncertainty of 4.8 degrees.
The angle from the Fermi LAT boresight is 147.0 degrees.
The skymap can be found here:
https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2023/bn230723194/quicklook/glg_skymap_all_bn230723194.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/bn230723194/quicklook/glg_healpix_all_bn230723194.fit
The GBM light curve can be found here:
https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2023/bn230723194/quicklook/glg_lc_medres34_bn230723194.gif