[vsnet-grb-info 18292] GRB160709A: Astrosat CZTI detection of short GRB

[GCN Circulars]

TITLE:   GCN CIRCULAR
NUMBER:  19740
SUBJECT: GRB160709A: Astrosat CZTI detection of short GRB
DATE:    16/07/29 04:24:51 GMT
FROM:    Varun Bhalerao at IUCAA  <varunb at iucaa.in>

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

Analysis of Astrosat data showed the CZTI detection of a short GRB 160709A (Fermi-LAT detection: Guiriec, et al., GCN Circ. 19675).

The GRB occured at an angle of 124 degrees away from the CZTI pointing direction. The source was clearly detected in the 40-200 keV energy range. The light curve shows a single peak at 19:49:04.00 UT, 0.5 seconds after Fermi Trigger at 19:49:03.50 and a peak count rate of 1035.0 counts/sec above the background (four quadrants summed together), with a total of 3878.0 counts. The local mean background count rate was 314.0 counts/sec. Using cumulative rates, we measure a T90 of 0.45 sec, consistent with the Konus-Wind measurement of 0.4s (Frederiks et al., GCN Circ. 19677) and CALET (Asaoka et al., GCN Circ. 19701) but inconsistent with Swift-BAT (Sakamoto et al., GCN Circ. 19681) and Fermi (Jenke et al., GCN Circ. 19676).

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.