TITLE:   GCN CIRCULAR
NUMBER:  33532
SUBJECT: GRB 230328B: AstroSat CZTI detection
DATE:    23/03/29 01:58:51 GMT
FROM:    Varun Bhalerao at Indian Inst of Tech  <varunb@iitb.ac.in>

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 GRB 230328B which was also detected by Fermi-GBM (GCN Circ. 33526), Swift-BAT (Gropp et. al, GCN Circ. 33527). 

The source was clearly detected in the 20-200 keV energy range. The light curve peaks at 2023-03-28 14:54:49.5 UTC. The measured peak count rate associated with the burst is 244.7 (+41.3 -43.3) counts/s above the background in the combined data of all quadrants, with a total of 1090 (+249 -250) counts. The local mean background count rate was 409.1 (+2.4 -3.1) counts/s. Using cumulative rates, we measure a T90 of 11.78 (+4.17 -4.51) s.

It was also clearly detected in the CsI anticoincidence (Veto) detector in the 100-500 keV energy range. The light curve peaks at 2023-03-28 14:54:48.3 UTC. The measured peak count rate is 561.0 (+68.3 -74.6) counts/s above the background in the combined Veto data of all quadrants, with a total of 2819 (+428 -485) counts. The local mean background count rate was 1299.3 (+5.2 -5.5) counts/s. We measure a T90 of 12.86 (+5.41 -4.68) 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