TITLE:   GCN CIRCULAR
NUMBER:  21327
SUBJECT: GRB 170705A: AstroSat CZTI detection
DATE:    17/07/12 13:18:15 GMT
FROM:    Vidushi Sharma at IUCAA  <vidushi@iucaa.in>

V. Sharma (IUCAA), V. Bhalerao (IIT-B), 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 the detection of a long-duration GRB 170705A, which was also detected by Swift/BAT (Starling et al., GCN 21289), Fermi/GBM (Bissaldi et al., GCN 21297), Konus-Wind (Svinkin et al., GCN 21299) and Insight-HXMT (Lu et al., GCN 21301).

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 02:46:00 UT, ~13 s after the Swift Trigger. The measured peak count rate is 635.9 cts/s above the background in combined data of four quadrants, with a total of 3123 cts. The local mean background count rate was 374.1 cts/s. Using cumulative rates, we measure a T90 of 14.9 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.