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GCN Circular 35348

Subject
GRB 231214A: AstroSat CZTI detection
Date
2023-12-15T12:16:26Z (6 months ago)
From
Gaurav Waratkar at IIT Bombay <gauravwaratkar@iitb.ac.in>
Via
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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 CIFT framework (Sharma et al., 2021, JApA, 42, 73) showed the detection of a long-duration GRB 231214A which was also detected by Fermi-GBM (Fermi GBM Team, GCN Circ. 35334), Swift-BAT (Brivio et al., GCN Circ. 35335), and Fermi-LAT (Kocevski et al., GCN Circ. 35342).

The source was clearly detected in three of four quadrants of CZT detectors in the 20-200 keV energy range. AstroSat was approaching the South Atlantic Anomaly (SAA) region and hence the background rates were higher. The light curve showed multiple peaks of emission with the strongest peak at 2023-12-14 20:24:41.50 UTC. We limit our analysis to a single quadrant with a relatively stable background. The measured peak count rate associated with the burst is 99 (+28, -12) counts/s above the background in the data of one quadrant (out of four), with a total of 691 (+127, -135) counts. The local mean background count rate was 99 (+2, -2) counts/s. Using cumulative rates, we measure a T90 of 20 (+1, -1) s.

The source was also 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 2023-12-14 20:24:29.95 UTC. The measured peak count rate associated with the burst is 245 (+84, -30) counts/s above the background in the combined data of all quadrants, with a total of 2761 (+591, -655) counts. The local mean background count rate was 1761 (+8, -9) counts/s. We measure a T90 of 22 (+3, -2) 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

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