Gamma-ray Burst 230803A

(All information courtesy of the instrument teams.)

Previous IAU Circulars

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Results of Observations

GCN NOTICE

TITLE:           GCN/FERMI NOTICE
NOTICE_DATE:     Thu 03 Aug 23 01:27:38 UT
NOTICE_TYPE:     Fermi-GBM Flight Position
RECORD_NUM:      44
TRIGGER_NUM:     712718833
GRB_RA:          145.233d {+09h 40m 56s} (J2000),
                 145.351d {+09h 41m 24s} (current),
                 144.982d {+09h 39m 56s} (1950)
GRB_DEC:         -67.883d {-67d 52' 59"} (J2000),
                 -67.991d {-67d 59' 27"} (current),
                 -67.655d {-67d 39' 17"} (1950)
GRB_ERROR:       5.93 [deg radius, statistical plus systematic]
GRB_INTEN:       431 [cnts/sec]
DATA_SIGNIF:     20.00 [sigma]
INTEG_TIME:      1.024 [sec]
GRB_DATE:        20159 TJD;   215 DOY;   23/08/03
GRB_TIME:        5228.15 SOD {01:27:08.15} UT
GRB_PHI:         273.00 [deg]
GRB_THETA:        60.00 [deg]
DATA_TIME_SCALE: 1.0240 [sec]
HARD_RATIO:      1.05
LOC_ALGORITHM:   3 (version number of)
MOST_LIKELY:      98%  GRB
2nd_MOST_LIKELY:   1%  Generic SGR
DETECTORS:       0,0,0, 1,1,0, 1,0,0, 0,0,0, 0,0,
SUN_POSTN:       132.95d {+08h 51m 47s}  +17.60d {+17d 36' 17"}
SUN_DIST:         86.07 [deg]   Sun_angle= -0.8 [hr] (East of Sun)
MOON_POSTN:      332.49d {+22h 09m 56s}  -15.95d {-15d 57' 01"}
MOON_DIST:        95.90 [deg]
MOON_ILLUM:      98 [%]
GAL_COORDS:      286.45,-11.34 [deg] galactic lon,lat of the burst (or transient)
ECL_COORDS:      209.01,-69.29 [deg] ecliptic lon,lat of the burst (or transient)
LC_URL:          http://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2023/bn230803061/quicklook/glg_lc_medres34_bn230803061.gif
COMMENTS:        Fermi-GBM Flight-calculated Coordinates.  
COMMENTS:        This trigger occurred at longitude,latitude = 97.35,-6.75 [deg].  
COMMENTS:        The LC_URL file will not be created until ~15 min after the trigger.

GCN NOTICE

TITLE:           GCN/FERMI NOTICE
NOTICE_DATE:     Thu 03 Aug 23 01:27:56 UT
NOTICE_TYPE:     Fermi-GBM Ground Position
RECORD_NUM:      58
TRIGGER_NUM:     712718833
GRB_RA:          152.280d {+10h 09m 07s} (J2000),
                 152.443d {+10h 09m 46s} (current),
                 151.934d {+10h 07m 44s} (1950)
GRB_DEC:         -66.300d {-66d 17' 59"} (J2000),
                 -66.416d {-66d 24' 58"} (current),
                 -66.054d {-66d 03' 13"} (1950)
GRB_ERROR:       2.60 [deg radius, statistical only]
DATA_SIGNIF:     21.80 [sigma]
DATA_INTERVAL:   2.048 [sec]
GRB_DATE:        20159 TJD;   215 DOY;   23/08/03
GRB_TIME:        5228.15 SOD {01:27:08.15} UT
GRB_PHI:         274.00 [deg]
GRB_THETA:        63.00 [deg]
E_RANGE:         44.032 - 279.965 [keV]
LOC_ALGORITHM:   4173 (Gnd S/W Version number)
SUN_POSTN:       132.95d {+08h 51m 47s}  +17.60d {+17d 36' 16"}
SUN_DIST:         85.28 [deg]   Sun_angle= -1.3 [hr] (East of Sun)
MOON_POSTN:      332.49d {+22h 09m 57s}  -15.95d {-15d 56' 57"}
MOON_DIST:        97.63 [deg]
MOON_ILLUM:      98 [%]
GAL_COORDS:      287.61, -8.39 [deg] galactic lon,lat of the burst (or transient)
ECL_COORDS:      208.44,-66.13 [deg] ecliptic lon,lat of the burst (or transient)
LC_URL:          http://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2023/bn230803061/quicklook/glg_lc_medres34_bn230803061.gif
POS_MAP_URL:     http://gcn.gsfc.nasa.gov/notices_f/gbm_gnd_loc_map_712718833.fits
COMMENTS:        Fermi-GBM Ground-calculated Coordinates.  
COMMENTS:        This Notice was ground-generated -- not flight-generated.  
COMMENTS:        The LC_URL file will not be created/available until ~15 min after the trigger.  
COMMENTS:        The POS_MAP_URL file will not be created/available until ~1.5 min after the notice.

GCN NOTICE

TITLE:           GCN/FERMI NOTICE
NOTICE_DATE:     Thu 03 Aug 23 01:36:36 UT
NOTICE_TYPE:     Fermi-GBM Final Position
RECORD_NUM:      0
TRIGGER_NUM:     712718833
GRB_RA:          158.410d {+10h 33m 38s} (J2000),
                 158.612d {+10h 34m 27s} (current),
                 157.984d {+10h 31m 56s} (1950)
GRB_DEC:         -64.380d {-64d 22' 47"} (J2000),
                 -64.502d {-64d 30' 07"} (current),
                 -64.122d {-64d 07' 16"} (1950)
GRB_ERROR:       3.33 [deg radius, statistical only]
GRB_DATE:        20159 TJD;   215 DOY;   23/08/03
GRB_TIME:        5228.15 SOD {01:27:08.15} UT
GRB_PHI:         275.00 [deg]
GRB_THETA:        66.00 [deg]
E_RANGE:         44.032 - 279.965 [keV]
LOC_ALGORITHM:   41731 (Gnd S/W Version number)
SUN_POSTN:       132.95d {+08h 51m 49s}  +17.60d {+17d 36' 11"}
SUN_DIST:         84.44 [deg]   Sun_angle= -1.7 [hr] (East of Sun)
MOON_POSTN:      332.58d {+22h 10m 18s}  -15.91d {-15d 54' 48"}
MOON_DIST:        99.45 [deg]
MOON_ILLUM:      97 [%]
GAL_COORDS:      288.71, -5.38 [deg] galactic lon,lat of the burst (or transient)
ECL_COORDS:      207.88,-62.94 [deg] ecliptic lon,lat of the burst (or transient)
LC_URL:          http://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2023/bn230803061/quicklook/glg_lc_medres34_bn230803061.gif
LOC_URL:         http://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2023/bn230803061/quicklook/glg_locplot_all_bn230803061.png
COMMENTS:        Fermi-GBM Final Position.  
COMMENTS:        This Notice was ground-generated -- not flight-generated.  
COMMENTS:        The LC_URL file should be available by the time this FINAL notice is produced.  
COMMENTS:        This notice was generated completely by automated pipeline processing.  
COMMENTS:        This is likely a Long GRB.

GCN Circular #34325
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
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
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
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=3D5229.064 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 =C2=B1 0.88)x10^-5 erg/cm^2 and a 64-ms peak energy flux, measured from T0 + 93.760 s, of (1.43 =C2=B1 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 =3D -1.30 (-0.06,+0.08), the high energy photon index beta =3D -2.65 (-0.82,+0.30), the peak energy Ep =3D 256 (-31,+32) keV, chi2 =3D 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 =3D -0.93 (-0.06,+0.07), the high energy photon index beta =3D -2.32 (-0.20,+0.14), the peak energy Ep =3D 284 (-38,+40) keV, chi2 =3D 66/77 dof.
All the quoted errors are estimated at the 90% confidence level. All the presented results are preliminary.

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Jochen Greiner, last update: 07-Aug-2023 [Disclaimer]