TITLE:   GCN CIRCULAR
NUMBER:  23248
SUBJECT: GRB 180914A: AstroSat CZTI detection
DATE:    18/09/17 18:46:42 GMT
FROM:    Vidushi Sharma at IUCAA  <vidushi@iucaa.in>

V. Sharma, T. Khanam and 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 long GRB 180914A, which was also detected by Fermi (LAT: Bissaldi E. et al., GCN 23225 and GBM: Poolakkil S. et al., GCN 23227), Swift (XRT: D'Elia V. et al., GCN 23229) and IPN Triangulation (Hurley K. et al., GCN 23247).

The source was clearly detected in the 40-200 keV energy range. The light curve shows multiple peaks of emission with strongest peak at 12:32:08.500 UT. The measured peak count rate is 874 cts/s above the background in combined data of four quadrants, with a total of 27940 cts. The local mean background count rate was 609 cts/s. Using cumulative rates, we measure a T90 of 125.4 s. In preliminary analysis, we find that 2142 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.