[vsnet-grb-info 19653] GRB 170726A: AstroSat CZTI detection

[GCN Circulars]

TITLE:   GCN CIRCULAR
NUMBER:  21397
SUBJECT: GRB 170726A: AstroSat CZTI detection
DATE:    17/07/31 14:44:12 GMT
FROM:    Vidushi Sharma at IUCAA  <vidushi at iucaa.in>

V. Sharma 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-duration GRB 170726A, which was also detected by Insight-HXMT (Li et al., GCN 21366), SPI-ACS (trig time: 2017-07-26 19:02:59.51) and
Fermi/GBM (trig time: 2017-07-26 19:02:59.976).

The source was clearly detected in the 40-200 keV energy range. The light curve shows multiple peaks of emission with the strongest peak at 19:03:00.976 UT, ~1 s after the Insight-HXMT Trigger. The measured peak count rate is 475.9 cts/s above the background in combined data of four quadrants, with a total of 5477 cts. The local mean background count rate was 377.1 cts/s. Using cumulative rates, we measure a T90 of 39.6 s.

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.