TITLE: GCN CIRCULAR NUMBER: 35999 SUBJECT: GRB 240329A: AstroSat CZTI detection DATE: 24/04/01 09:56:46 GMT FROM: Gaurav Waratkar at IIT Bombay gauravwaratkar24@gmail.com
J. Joshi (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 240329A which was also detected by Fermi GBM (Fermi-GBM team, GCN Circ. 35993), and GRBAlpha (Dafcikova et al., GCN Circ. 35997).
The source was clearly detected in the CZT detectors in the 20-200 keV energy range. The light curve showed multiple peaks of emission with the strongest peak at 2024-03-29 21:43:08.05 UTC. The measured peak count rate associated with the burst is 481 (+186, -13) counts/s above the background in the combined data of all quadrants, with a total of 860 (+162, -170) counts. The local mean background count rate was 326 (+6, -8) counts/s. Using cumulative rates, we measure a T90 of 4.12 (+2.37, -0.59) s.
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 2024-03-29 21:43:10.08 UTC. The measured peak count rate associated with the burst is 245 (+67, -51) counts/s above the background in the combined data of all quadrants, with a total of 898 (+288, -307) counts. The local mean background count rate was 1418 (+4, -5) counts/s. We measure a T90 of 7.53 (+3.73, -3.85) 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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