TITLE:   GCN CIRCULAR
NUMBER:  22557
SUBJECT: GRB180325A: AstroSat CZTI detection
DATE:    18/03/29 10:36:12 GMT
FROM:    Vidushi Sharma at IUCAA  <vidushi@iucaa.in>

V. Sharma (IUCAA), V. Bhalerao (IIT-B), D. Bhattacharya (IUCAA), A. R. Rao (TIFR) and S. Vadawale (PRL) report on behalf of the AstroSat CZTI collaboration:

Analysis of AstroSat CZTI data showed the detection of a long GRB 180325A, which was also detected by Swift (Troja E. et al., GCN 22532), Swift-BAT (Lien A. Y. et al., GCN 22454), Swift-XRT (Page K.L. et al., GCN 22540) and Konus-Wind (Frederiks D. et al., GCN 22546).

The source was clearly detected in the 40-200 keV energy range. The light curve shows single peak of emission at 01:54:23.0 UT, ~81 s after Swift-BAT trigger time. The measured peak count rate is 1093.8 cts/s above the background in combined data of four quadrants, with a total of 5294 cts. The local mean background count rate was 510.2 cts/s. Using cumulative rates, we measure a T90 of 15.7 s. In Preliminary analysis, we find that 495.2 compton events are associated with this event.

It was also clearly detected in the CsI anticoincidence (Veto) detector in the 100-500 keV energy range.

CZTI GRB detections are reported regularly on the payload site at http://astrosat.iucaa.in/czti/?q=grb. CZTI is built by a TIFR-led consortium of institutes across India, including VSSC, ISAC, IUCAA, SAC and PRL. The Indian Space Research Organisation funded, managed and facilitated the project.