TITLE:   GCN CIRCULAR
NUMBER:  22441
SUBJECT: GRB 180218A: AstroSat CZTI detection
DATE:    18/02/24 15:17:31 GMT
FROM:    Vidushi Sharma at IUCAA  <vidushi@iucaa.in>

V. Sharma (IUCAA), D. Bhattacharya (IUCAA), V. Bhalerao (IIT-B), 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 bright GRB 180218A, which was also detected by IPN Triangulation(Svinkin D. et al., GCN 22423), Fermi-GBM (Poolakkil S. et al., GCN 22424), CALET (Ishizaki W. et al., GCN 22425) and Konus-Wind (Frederiks D. et al., GCN 22426).

The source was clearly detected in the 40-200 keV energy range. The light curve shows multiple peaks of emission with strongest peak at 15:14:10.5 UT. The measured peak count rate is 1360.5 cts/s above the background in combined data of four quadrants, with a total of 4651 cts. The local mean background count rate was 491.4 cts/s. Using cumulative rates, we measure a T90 of 4.9 s. In Preliminary analysis, we find that 380.4 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.