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GCN Circular 35704

Subject
GRB 240205B: AstroSat CZTI detection
Date
2024-02-08T15:28:38Z (5 months ago)
From
Gaurav Waratkar at IIT Bombay <gauravwaratkar24@gmail.com>
Via
Web form
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 240205B which was also detected by Fermi-GBM (Fermi GBM team, GCN Circ. 35682), Swift-BAT (Moss et al., GCN Circ. 35683), and GECAM (Zhang et al., GCN Circ. 35689).

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 2024-02-05 22:13:46.50 UTC. The measured peak count rate associated with the burst is 731 (+51, -56) counts/s above the background in the combined data of all quadrants, with a total of 3027 (+294, -448) counts. The local mean background count rate was 295 (+3, -2) counts/s. Using cumulative rates, we measure a T90 of 43 (+3, -2) 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 2024-02-05 22:13:45.31 UTC. The measured peak count rate associated with the burst is 632 (+69, -74) counts/s above the background in the combined data of all quadrants, with a total of 2944 (+573, -674) counts. The local mean background count rate was 1220 (+4, -6) counts/s. We measure a T90 of 42 (+2, -3) 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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