[vsnet-grb-info 26770] GRB 201104A: AstroSat CZTI detection

[GCN Circulars]

TITLE:   GCN CIRCULAR
NUMBER:  28873
SUBJECT: GRB 201104A: AstroSat CZTI detection
DATE:    20/11/09 20:42:02 GMT
FROM:    Soumya Gupta at IUCAA/ASTROSAT  <soumya at iucaa>

S. Gupta, V. Sharma and D. Bhattacharya (IUCAA), V. Bhalerao (IIT-B), A. R. Rao (IUCAA/TIFR) and S. Vadawale (PRL) report on behalf of the AstroSat CZTI collaboration:

The AstroSat CZT Imager recorded a transient event in all four of its CsI anticoincidence (Veto) detectors in the 100-500 keV energy range, coincident with the long GRB 201104A reported by Fermi GBM (GCN #28823), Global MASTER-Net (Lipunov V. et al., GCN #28824), Fermi LAT (Ohno M. et al., GCN #28828), AGILE/MCAL (Ursi A. et al., GCN #28829), Fermi GBM (Bissaldi E. et al., GCN #28830), Tiled Swift (Evans P. et al., GCN #28832), BALROG (Kunzweiler F. et al., GCN #28834) and Swift-XRT (D'Elia V. et al., GCN #28859). There was a weak detection in the main CZT detectors in the 40-200 keV energy range.

The light curve showed multiple peaks of emission with the strongest peak at 2020-11-04 00:00:55.000 UT. The measured peak count rate is 1757 +/- 68 cts/s above the background in the combined Veto data of four quadrants, with a total of 6949 +/- 80 cts. The local mean background count rate was 2774 +/- 5 cts/s.  We measure a T90 of 8.18 +/- 0.13 s from the cumulative Veto light curve.

In the main CZT detectors, the light curve showed multiple peaks of emission with the strongest peak at 2020-11-04 00:00:56.000 UT. The measured peak count rate associated with the burst is 330 +/- 33 cts/s above the background in the combined data of four quadrants, with a total of 1170 +/- 23 cts. The local mean background count rate was  792 +/- 2 cts/s. Using cumulative rates, we measure a T90 of 7.36 +/- 0.11 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.