[vsnet-grb-info 28446] GRB 210727A: AstroSat CZTI detection

[GCN Circulars]

TITLE:   GCN CIRCULAR
NUMBER:  30549
SUBJECT: GRB 210727A: AstroSat CZTI detection
DATE:    21/07/30 06:21:59 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 210727A, which
was also detected by Fermi-GBM (Trigger no. 649072251), AGILE/MCAL (Ursi
et al., GCN 30533), CALET (Akaike et al., GCN 30544), with IPN
localization (Ridnaia et al., GCN 30541) and BALROG localization
(Biltzinger et al., GCN 30531). 

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
2021-07-27 09:50:46.45 UT. The measured peak count rate associated with
the burst is 890 (+197, -153) cts/s above the background in the combined
data of four quadrants, with a total of 489 (+74, -67) cts. The local
mean background count rate was 482 (+11, -15) cts/s. Using cumulative
rates, we measure a T90 of 0.9 (+0.3, -0.1) s.

It was also 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.