TITLE:   GCN CIRCULAR
NUMBER:  21856
SUBJECT: GRB 170906A: AstroSat CZTI(Veto) detection
DATE:    17/09/11 14:29:14 GMT
FROM:    Vidushi Sharma at IUCAA  <vidushi@iucaa.in>

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

The bright GRB 170906A was detected using the CsI veto detectors on Astrosat CZTI (Bhalerao et al., arXiv:1608.03408),  which was also detected by Swift (Siegel M.H. et al., GCN Circ. 21821) and Fermi GBM (Hamburg R. et al, GCN Circ. 21839).

The source was clearly detected in the 125-250 keV energy range. The light curve shows a multiple peak structure. The peak count rate in the CsI detectors was 2262 counts/sec above the background (four quadrants summed together), with a total of 49316 counts. The local mean background count rate was 1606.7 counts/sec. Using cumulative rates, we measure a T90 of 70.5 secs.

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.