TITLE:   GCN CIRCULAR
NUMBER:  22313
SUBJECT: GRB 171227A: AstroSat CZTI detection
DATE:    18/01/10 09:49:08 GMT
FROM:    Vidushi Sharma at IUCAA  <vidushi@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 bright GRB 171227A, which was also detected by AGILE/MCAL (Verrecchia F. et al., GCN 22288), Fermi-GBM (Hui C. M. et al., GCN 22289), IPN Triangulation (Kozlova A. et al., GCN 22290) and Konus-Wind (Tsvetkova A. et al., GCN 22291).

The source was clearly detected in the 40-200 keV energy range. The light curve shows multiple peaks of emission with strongest peak at 00:00:32.500 UT, ~19 s after the Fermi-GBM trigger. The measured peak count rate is 2066.8 cts/s above the background in combined data of four quadrants, with a total of 15305 cts. The local mean background count rate was 471 cts/s. Using cumulative rates, we measure a T90 of 25.4 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.