TITLE:   GCN CIRCULAR
NUMBER:  24845
SUBJECT: GRB 190611B: AstroSat CZTI detection
DATE:    19/06/18 04:27:34 GMT
FROM:    Prachee Ghumatkar at IUCAA/AstroSat  <prachee@iucaa.in>

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

Analysis of AstroSat CZTI data showed the detection of a long GRB 190611B, which was also detected by Fermi GBM (Malacaria C. et al., GCN #24794), Global MASTER-Net (Lipunov V. et al., GCN #24795), IPN Triangulation (Hurley K. et al., GCN #24811), BALROG (Kunzweiler F. et al., GCN #24813), Konus-Wind (Frederiks D. et al., GCN #24827) and CALET (Cannady N. et al., GCN #24830).

The source was clearly detected in the 40-200 keV energy range. The light curve shows multiple pulses of emission with the strongest peak at 22:47:51.5 UT. Fermi/GBM lightcurve consists of two broad pulses. AstroSat could detect only first pulse of the burst, as during the second pulse the detector was in South Atlantic Anomaly (SAA). The measured peak count rate associated with the burst is 387 cts/s above the background in the combined data of four quadrants, with a total of 1251 cts. The local mean background count rate was 578 cts/s. Using cumulative rates, we measure a T90 of 7.35 s.

It was also clearly 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.