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GCN Circular 35072

Subject
GRB 231117A: AstroSat CZTI detection of a bright short burst
Date
2023-11-17T07:09:52Z (3 months 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 CIFT framework (Sharma et al., 2021, JApA, 42, 73) showed the detection of a bright short duration GRB 231117A which was also detected by Swift-BAT (Laha et al., GCN Circ. 35071), and CALET (Trigger 1384225326).

The source was clearly detected in the CZT detectors in the 20-200 keV energy range. The light curve peaks at 2023-11-17 03:03:19.74 UTC. The measured peak count rate associated with the burst is 8467 (+1562, -767) counts/s above the background in the combined data of all quadrants, with a total of 1375 (+86, -77) counts. The local mean background count rate was 335 (+15, -38) counts/s. Using cumulative rates, we measure a T90 of 0.42 (+0.04, -0.06) s.

The source was also clearly detected in the CsI anticoincidence (Veto) detector in the 100-500 keV energy range. The light curve peaks at 2023-11-17 03:03:18.82 UTC. The measured peak count rate associated with the burst is 1496 (+86, -96) counts/s above the background in the combined data of all quadrants, with a total of 1883 (+307, -334) counts. The local mean background count rate was 1497 (+6, -7) counts/s. Due to the intrinsic 1 s binning of Veto data, we cannot reliably estimate a T90 from it.

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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