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GCN Circular 34283

Subject
GRB 230727A: AstroSat CZTI detection
Date
2023-07-28T06:47:03Z (10 months ago)
From
Gaurav Waratkar at IIT Bombay <gauravwaratkar@iitb.ac.in>
Via
email
B. Pari (IITB), 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 GRB 230727A which was also detected by Fermi (Fermi GBM Team, GCN Circ. 34275) and Swift/BAT-GUANO (DeLaunay et al., GCN Circ. 34280).

The source was clearly detected in the 20-200 keV energy range. The light curve peaks at 2023-07-27 11:03:09.45 UTC. The measured peak count rate associated with the burst is 709.2 (+211.2, -56.0) counts/s above the background in the combined data of all quadrants, with a total of 1916 (+278, -290) counts. The local mean background count rate was 522.1 (+5.0, -7.7) counts/s. Using cumulative rates, we measure a T90 of 11.8 (+2.5, -1.6) 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 2023-07-27 11:03:08.85 UTC. The measured peak count rate associated with the burst is 343.3 (+76.9, -79.7) counts/s above the background in the combined data of all quadrants, with a total of 1231 (+419, -444) counts. The local mean background count rate was 1992.2 (+5.8, -7.1) counts/s. We measure a T90 of 11.3 (+3.7, -5.1) 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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