GRB 240731A
GCN Circular 36989
Subject
GRB 240731A: AstroSat CZTI detection
Date
2024-07-31T19:41:44Z (a year ago)
From
Gaurav Waratkar at IIT Bombay <gauravwaratkar@iitb.ac.in>
Via
Web form
S. Srijan (IITB), A. Dasgupta (BITS Pilani, Hyderabad), G. Waratkar (IITB), J. Joshi (IUCAA), 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 CIFT framework (Sharma et al., 2021, JApA, 42, 73) showed the detection of GRB 240731A which was also detected by Fermi/GBM (Trigger 744128417) and INTEGRAL/SPI-ACS (Trigger 10826).
The source was detected in the CsI anticoincidence (Veto) detector in the 100-500 keV energy range. The light curve peaks at 2024-07-31 14:20:13.3 UTC. The measured peak count rate is 364 (+70, -74) counts/s above the background in the combined Veto data of all quadrants, with a total of 672 (+315, -330) counts. The local mean background count rate was 1305 (+13, -14) counts/s. We measure a T90 of 3.4 (+2.9, -2.4) 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 36992
Subject
GRB 240731A: Fermi GBM Final Localization
Date
2024-07-31T20:44:01Z (a year ago)
From
Vidushi Sharma at NASA GSFC/UMBC <vidushi.sharma@nasa.gov>
Via
Web form
The Fermi GBM team reports the detection of a likely LONG GRB,
which was also detected by AstroSat (Srijan et al. 2024, GCN 36989)
and INTEGRAL SPI ACS trigger 10826.
"At 14:20:12.45 UT on 31 July 2024, the Fermi Gamma-ray Burst Monitor (GBM)
triggered and located GRB 240731A (trigger 744128417/240731597).
The on-ground calculated location, using the Fermi GBM trigger data,
is RA = 8.65, Dec = -46.27 (J2000 degrees, equivalent to J2000 0h 34m, -46d 16'),
with a statistical uncertainty of 6.55 degrees.
The angle from the Fermi LAT boresight is 58 degrees.
The skymap can be found here:
https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2024/bn240731597/quicklook/glg_skymap_all_bn240731597.png
The HEALPix FITS file, including the estimated localization systematic, can be found here:
https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2024/bn240731597/quicklook/glg_healpix_all_bn240731597.fit
The GBM light curve can be found here:
https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2024/bn240731597/quicklook/glg_lc_medres34_bn240731597.gif"