TITLE:   GCN CIRCULAR
NUMBER:  21163
SUBJECT: GRB 170511A: AstroSat CZTI detection
DATE:    17/05/30 09:20:19 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 data showed the CZTI detection of a bright GRB 170511A which was also detected by MAXI/GSC (Takao et al., GCN 21137), CALET GBM (Yamaoka et al., GCN 21146) and Fermi GBM (E. Bissaldi et al., GCN 21161).

The source was clearly detected in the 40-200 keV energy range. The light curve shows multiple peaks emission with the strongest peak at 05:59:40.920 UT, ~30 s after the Fermi Trigger. The measured peak count rate is 515.9 cts/s above the background in combined data of four quadrants, with a total of 5191 cts. The local mean background count rate was 373 cts/s. Using cumulative rates, we measure a T90 of 36.6 s.

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.