TITLE:   GCN CIRCULAR
NUMBER:  21006
SUBJECT: GRB 170402A: AstroSat CZTI detection
DATE:    17/04/10 11:09:17 GMT
FROM:    Vidushi Sharma at IUCAA  <vidushi@iucaa.in>

V. Sharma, V. Bhalerao (IITB) and 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 clear detection of GRB 170402A (CALET Gamma-Ray Burst Monitor detection: T. Sakamoto et al., GCN Circ. 20980) in the 40-200 keV energy range in the quadrant C and D only. The light curve shows multiple peak emission with main peak at 06:50:57.076 UT, ~5 s after the CALET trigger. The measured peak count rate is 323.4 counts/sec above the background in combined data of four quadrants, with a total 2197 counts. The local mean background count rate was 363.6 counts/s. Using cumulative rates, we measure a T90 of 13 s.

It was clearly detected in the CsI anticoincidence detector (Veto) also as 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.