TITLE:   GCN CIRCULAR
NUMBER:  20670
SUBJECT: GRB 170209A: AstroSat CZTI detection
DATE:    17/02/13 20:10:05 GMT
FROM:    Vidushi Sharma at IUCAA  <vidushi@iucaa.in>

V. Sharma and D. Bhattacharya (IUCAA), V. Bhalerao (IITB), A. R. Rao (TIFR) and S. Vadawale (PRL) report on behalf of the AstroSat CZTI collaboration:

Analysis of AstroSat CZTI data showed a clear detection of GRB 170209A (Fermi GBM detection: O.J. Roberts et al., GCN Circ. 20652) in the 40-200 keV energy range. The light curve showed multiple peaks emission. The first emission peak occurred at 01:08:40.08 UT, 2 s after the Fermi trigger and a second group of emission peaked at ~34 s after the trigger. An interval of ~9 s between these two showed no detectable emission. The measured peak count rate was 245.1 counts/s above the background in combined data of four quadrants, with a total 1453.0 counts. The local mean background count rate was 343.9 counts/s. Using cumulative rates, we measured a T90 of 40.4 s.

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