GRB 230803A
GCN Circular 34325
Subject
GRB 230803A: Fermi GBM Final Real-time Localization
Date
2023-08-03T01:37:47Z (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 01:27:08 UT on 3 Aug 2023, the Fermi Gamma-ray Burst Monitor (GBM) triggered and located GRB 230803A (trigger 712718833.154354 / 230803061).
The on-ground calculated location, using the Fermi GBM trigger data, is RA = 158.4, Dec = -64.4 (J2000 degrees, equivalent to J2000 10h 33m, -64d 24'), with a statistical uncertainty of 3.3 degrees.
The angle from the Fermi LAT boresight is 66.0 degrees.
The skymap can be found here:
https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2023/bn230803061/quicklook/glg_skymap_all_bn230803061.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/bn230803061/quicklook/glg_healpix_all_bn230803061.fit
The GBM light curve can be found here:
https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2023/bn230803061/quicklook/glg_lc_medres34_bn230803061.gif
GCN Circular 34328
Subject
GRB 230803A: AstroSat CZTI detection
Date
2023-08-03T12:04:58Z (2 years ago)
From
Gaurav Waratkar at IIT Bombay <gauravwaratkar@iitb.ac.in>
Via
Web form
P. K. Navaneeth (IUCAA), G. Waratkar (IITB), A. Vibhute (IUCAA), V. Bhalerao (IITB), D. Bhattacharya (Ashoka University/IUCAA), A. R. Rao (IUCAA/TIFR), and S. Vadawale (PRL) report on behalf of the AstroSat CZTI collaboration:
Analysis of AstroSat CZTI data with the ML pipeline (Abraham et al., 2021, MNRAS, 504, 3084) and the CIFT framework (Sharma et al., 2021, JApA, 42, 73) showed the detection of a bright long GRB 230803A which was also detected by Fermi (Fermi GBM Team, GCN Circ. 34325).
The source was clearly detected in the 20-200 keV energy range. The light curve showed multiple peaks of emission with the strongest peak at 2023-08-03 01:28:42.50 UTC. The measured peak count rate associated with the burst is 783 (+56, -59) counts/s above the background in the combined data of all quadrants, with a total of 5492 (+498, -481) counts. The local mean background count rate was 430 (+3, -3) counts/s. Using cumulative rates, we measure a T90 of 25 (+2, -1) s. In the preliminary analysis, we find 371 Compton events associated with this event.
The source was also clearly detected in the CsI anticoincidence (Veto) detector in the 100-500 keV energy range. The light curve showed multiple peaks of emission with the strongest peak at 2023-08-03 01:28:42.63 UTC. The measured peak count rate associated with the burst is 2196 (+97, -102) counts/s above the background in the combined data of all quadrants, with a total of 15329 (+934, -934) counts. The local mean background count rate was 1365 (+7, -5) counts/s. We measure a T90 of 26 (+2, -1) s from the cumulative Veto light curve.
CZTI is built by a TIFR-led consortium of institutes across India, including VSSC, URSC, IUCAA, SAC, and PRL. The Indian Space Research Organisation funded, managed, and facilitated the project.
CZTI GRB detections are reported regularly on the payload site at:
http://astrosat.iucaa.in/czti/?q=grb
GCN Circular 34330
Subject
IPN triangulation of GRB 230803A
Date
2023-08-03T20:39:17Z (2 years ago)
From
Anna Ridnaia at Ioffe Institute <ridnaia@mail.ioffe.ru>
Via
Web form
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,
E. Bozzo and C. Ferrigno, on behalf of the INTEGRAL SPI-ACS GRB 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 long-duration GRB 230803A
(Fermi GBM detection: Fermi GBM team, GCN 34325;
AstroSat CZTI detection: Navaneeth et al., GCN 34328)
has been detected by Fermi (GBM), Konus-Wind,
INTEGRAL (SPI-ACS), AstroSat (CZTI), and
Mars-Odyssey (HEND), so far, at about 5228 s UT (01:27:08).
We have triangulated it to a preliminary, 3 sigma error box
whose coordinates are:
---------------------------------------------
RA(2000), deg Dec(2000), deg
---------------------------------------------
Center:
150.510 (10h 02m 02s) -64.987 (-64d 59' 12")
Corners:
147.455 (09h 49m 49s) -64.554 (-64d 33' 15")
147.329 (09h 49m 19s) -64.581 (-64d 34' 51")
153.688 (10h 14m 45s) -65.347 (-65d 20' 50")
153.812 (10h 15m 15s) -65.315 (-65d 18' 54")
---------------------------------------------
The error box area is 431 sq. arcmin, and its maximum
dimension is 2.8 deg (the minimum one is 3 arcmin).
The Sun distance was 83 deg.
The IPN localization is consistent with, but reduces
the area of, the Fermi-GBM final localization (GCN 34325).
This localization may be improved.
A triangulation map and HEALPix FITS file are posted at
http://www.ioffe.ru/LEA/GRBs/GRB230803_T05229/IPN/
The Konus-Wind time history and spectrum will be given
in a forthcoming GCN Circular.
GCN Circular 34358
Subject
Konus-Wind detection of GRB 230803A
Date
2023-08-07T15:47:20Z (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 GRB 230803A (Fermi GBM detection: Fermi GBM team, GCN 34325;
AstroSat CZTI detection: Navaneeth et al., GCN 34328;
IPN triangulation: Kozyrev et al., GCN 34330)
triggered Konus-Wind (KW) at T0=5229.064 s UT (01:27:09.064).
The burst light curve shows a multi-peaked structure
with a total duration of ~126 s.
The emission is seen up to ~2 MeV.
The Konus-Wind light curve of this GRB is available at
http://www.ioffe.ru/LEA/GRBs/GRB230803_T05229/
As observed by Konus-Wind, the burst had
a fluence of (7.59 ± 0.88)x10^-5 erg/cm^2 and
a 64-ms peak energy flux, measured from T0 + 93.760 s,
of (1.43 ± 0.13)x10^-5 erg/cm^2/s (both in the 20 keV - 10 MeV energy range).
The time-integrated spectrum (measured from T0+57.600 to T0+128.256 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 = -1.30 (-0.06,+0.08),
the high energy photon index beta = -2.65 (-0.82,+0.30),
the peak energy Ep = 256 (-31,+32) keV,
chi2 = 112/97 dof.
The spectrum near the peak count rate (measured from T0+90.368 to T0+95.488 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 = -0.93 (-0.06,+0.07),
the high energy photon index beta = -2.32 (-0.20,+0.14),
the peak energy Ep = 284 (-38,+40) keV,
chi2 = 66/77 dof.
All the quoted errors are estimated at the 90% confidence level.
All the presented results are preliminary.