[vsnet-grb-info 28275] GRB 210704A: AstroSat CZTI detection

[GCN Circulars]

TITLE:   GCN CIRCULAR
NUMBER:  30378
SUBJECT: GRB 210704A: AstroSat CZTI detection
DATE:    21/07/05 15:15:59 GMT
FROM:    Gaurav Waratkar at IIT,Bombay  <gauravwaratkar at iitb.ac.in>

 V. Prasad (IUCAA), P. Sawant (IUCAA), G. Waratkar (IITB), A. Vibhute
(IUCAA), V. Bhalerao (IITB), D. Bhattacharya (IUCAA), A. R. Rao
(IUCAA/TIFR), and S. Vadawale (PRL) report on behalf of the AstroSat
CZTI collaboration: 

Analysis of AstroSat CZTI data with the CIFT framework (Sharma et al,
2020, arxiv:2011.07067) showed detection of a short GRB 210704A, which
was also detected by Fermi - GBM (Trigger 647120009 / GRB210704815),
Fermi-LAT (GCN 30375), and AGILE/MCAL (GCN 30372). 

The source was clearly detected in the 20-200 keV energy range. The
light curve showed multiple peaks of emission with the strongest peak at
2021-07-04 19:33:24.4 UT. The measured peak count rate associated with
the burst is 706 (+179, -132) cts/s above the background in the combined
data of four quadrants, with a total of 359 (+106, -109) cts. The local
mean background count rate was 489 (+6, -8) cts/s. Using cumulative
rates, we measure a T90 of 1.0 (+0.4, -0.4) s.  

It was also clearly detected in the CsI anticoincidence (Veto) detector
in the 100-500 keV energy range. In one-second bins, the measured peak
count rate associated with the burst is 1417.7 (+89.9 -97.4) cts/s above
the background in the combined data of four quadrants, with a total of
2430 (+327 -361) cts. The local mean background count rate was 1743.4
(+4.2 -4.2) cts/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.