{
  "bibcode": "2021GCN.29410....1W",
  "body": "G. Waratkar (IITB), V. Shenoy (IITB), A. Vibhute (IUCAA), S. Gupta \n(IUCAA), P. Sawant (IUCAA), V. Bhalerao (IITB), D. Bhattacharya (IUCAA), \nA. R. Rao (IUCAA/TIFR), and S. Vadawale (PRL) report on behalf of the \nAstroSat CZTI collaboration:\n\nAnalysis of AstroSat CZTI data with the CIFT framework (Sharma et al, \n2020, arxiv:2011.07067) showed detection of a bright long GRB 210204A, \nwhich was also detected by Fermi-GBM (GCN #29390, #29393) and GECAM-B \n(GCN #29392).\n\nThe source was clearly detected in the 20-200 keV energy range. The \nlight curve showed two isolated emission peaks with the stronger peak at \n2021-02-04 06:32:45 UT in all four quadrants. The measured peak count \nrate associated with the burst is 789 (+58, -61) cts/s above the \nbackground in the combined data of four quadrants, with a total of 18141 \n(+1631, -1364) cts. The initial fainter peak contributed to about 6% of \nthe reported total counts. The local mean background count rate was 480 \n(+2, -3) cts/s. Using cumulative rates, we measure a T90 of 200 (+7, \n-10) s.\n\nIt was also clearly detected in the CsI anticoincidence (Veto) detector \nin the 100-500 keV energy range. The light curve showed two isolated \npeaks of emission with the stronger peak at 2021-02-04 06:32:45 UT. The \ninitial fainter peak contributed less than 5% of total counts and hence \nwas excluded from the following analysis. The measured peak count rate \nis 754 (+76, -80) cts/s above the background in the combined Veto data \nof four quadrants, with a total of 15971 (+827, -996) cts. The local \nmean background count rate was 1575 (+2, -3) cts/s. We measure a T90 of \n57 (+7, -5) s from the cumulative Veto light curve.\n\nCZTI GRB detections are reported regularly on the payload site at \nhttp://astrosat.iucaa.in/czti/?q=grb. CZTI is built by a TIFR-led \nconsortium of institutes across India, including VSSC, ISAC, IUCAA, SAC \nand PRL. The Indian Space Research Organisation funded, managed and \nfacilitated the project.",
  "circularId": 29410,
  "createdOn": 1612608402000,
  "email": "gauravwaratkar@iitb.ac.in",
  "subject": "GRB 210204A: AstroSat CZTI Detection",
  "submitter": "Gaurav Waratkar at IIT,Bombay  <gauravwaratkar@iitb.ac.in>",
  "eventId": "GRB 210204A"
}