[vsnet-grb-info 20325] GRB 180112A: AstroSat CZTI detection

[GCN Circulars]

TITLE:   GCN CIRCULAR
NUMBER:  22421
SUBJECT: GRB 180112A: AstroSat CZTI detection
DATE:    18/02/19 07:17:20 GMT
FROM:    Varun Bhalerao at Indian Inst of Tech  <varunb at iitb.ac.in>

Y. Sharma (IITB), V. Sharma (IUCAA), Arvind B. (IISER Pune), 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 long duration GRB 180112A, which was also detected by Insight-HXMT (C. Z. Liu et al., GCN 22353), CALET (S. Ozawa et al., GCN 22358), Konus Wind (Trigger time: 16:29:11.736) and INTEGRAL SPI-ACS (Trigger time : 16:30:38).

The source was clearly detected in the 40-200 keV energy range. The light curve shows three distinc peaks, starting with a weak peak at 16:29:09 (UT) followed by two strong peaks at 16:30:45 (UT) and 16:32:54 (UT) respectively. The measured peak count rate is 96 cts/s above the background in combined data of four quadrants, with a total of 37730 cts. The local mean background count rate was 479 cts/s. Using cumulative rates, we measure a T90 of 209 s.

All three peaks of GRB were 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.