{
  "bibcode": "2021GCN.29299....1N",
  "body": "D. Nadella (NITK), G. Waratkar (IITB), A. Vibhute (IUCAA), S. Gupta\n(IUCAA), P. Sawant (IUCAA), V. Bhalerao (IITB), D. Bhattacharya (IUCAA), A.\nR. Rao (IUCAA/TIFR), and S. Vadawale (PRL) report on behalf of the AstroSat\nCZTI collaboration:\n\nAnalysis of AstroSat CZTI data with the CIFT framework (Sharma et al, 2020,\narxiv:2011.07067) showed detection of a bright long GRB 210104A, which was\nalso detected by Fermi-GBM (GCN #29232), Swift-BAT (GCN #29233), Konus-Wind\n(GCN #29258) and CALET-CGBM (GCN #29268).\n\nThe source was clearly detected in the 20-200 keV energy range. The light\ncurve showed multiple peaks of emission with the strongest peak at\n2021-01-04 11:27:17.5 UT. The measured peak count rate associated with the\nburst is 867 (+60, -56) cts/s above the background in the combined data of\nfour quadrants, with a total of 7003 (+407, -394) cts. The local mean\nbackground count rate was 555 (+2, -2) cts/s. Using cumulative rates, we\nmeasure a T90 of  33 (+7, -1) s.\n\nIt was also clearly detected in the CsI anticoincidence (Veto) detector in\nthe 100-500 keV energy range. The light curve showed multiple peaks of\nemission with the strongest peak at 2021-01-04 11:27:17 UT. The measured\npeak count rate is 606 (+86, -55) cts/s above the background in the\ncombined Veto data of four quadrants, with a total of 4520 (+693, -789)\ncts. The local mean background count rate was 2009 (+4, -5) cts/s. We\nmeasure a T90 of 35 (+7, -14) 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 and\nPRL. The Indian Space Research Organisation funded, managed and facilitated\nthe project.",
  "circularId": 29299,
  "createdOn": 1610562267000,
  "email": "gauravwaratkar24@gmail.com",
  "subject": "GRB 210104A: AstroSat CZTI detection",
  "submitter": "Gaurav Waratkar at IIT Bombay  <gauravwaratkar24@gmail.com>",
  "eventId": "GRB 210104A"
}