GCN Circular 29817

P. Sawant (IUCAA), G. Waratkar (IITB), A. Vibhute (IUCAA), S. Gupta
(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 long GRB 210410A, which was also
detected by Fermi-GBM (GCN #29777, #29788), Swift-XRT (GCN #29778, #29790),
Fermi-LAT (GCN #29781), Swift-BAT (GCN #29793), Konus-Wind (GCN #29797) and
AGILE-MCAL (GCN #29798).

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
2021-04-10 00:53:16.50 UT. Quadrant D was noisy, and we exclude it from
further analysis. The measured peak count rate associated with the burst is
225 (+45, -16) cts/s above the background in the combined data of four
quadrants, with a total of 1808 (+239, -299) cts. The local mean background
count rate was 373  (+2, -2) cts/s. Using cumulative rates, we measure a
T90 of 20 (+6, -7) s.

It was also clearly detected in the CsI anticoincidence (Veto) detector in
the 100-500 keV energy range. The light curve showed multiple peaks of
emission with the strongest peak at 2021-04-10 00:53:15.867 UT. The
measured peak count rate is 1149 (+91, -57) cts/s above the background in
the combined Veto data of four quadrants, with a total of 8483 (+515, -574)
cts. The local mean background count rate was 1580 (+4, -4) cts/s. We
measure a T90 of 18 (+6, -4) s from the cumulative Veto light curve.

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.