{
  "bibcode": "2021GCN.29828....1L",
  "body": "S. Laha (GSFC/UMBC/CRESST), E. Ambrosi (INAF-IASFPA),\nA. D'Ai (INAF-IASFPA), V. D'Elia (SSDC & INAF-OAR),\nJ. A. Kennea (PSU), K. L. Page (U Leicester) and D. M. Palmer (LANL)\nreport on behalf of the Neil Gehrels Swift Observatory Team:\n\nAt 06:53:41 UT, the Swift Burst Alert Telescope (BAT) triggered and\nlocated GRB 210419A (trigger=1044032).  Swift slewed immediately to the burst. \nThe BAT on-board calculated location is \nRA, Dec 86.862, -65.539 which is \n   RA(J2000) = 05h 47m 27s\n   Dec(J2000) = -65d 32' 20\"\nwith an uncertainty of 3 arcmin (radius, 90% containment, including \nsystematic uncertainty).  As is usual for an image trigger, no\nobvious variation is visible in the immediately-available lightcurve. \n\nThe XRT began observing the field at 06:55:49.0 UT, 127.9 seconds after\nthe BAT trigger. Using promptly downlinked data we find a bright,\nfading, uncatalogued X-ray source located at RA, Dec 86.85414,\n-65.50357 which is equivalent to:\n   RA(J2000)  = 05h 47m 24.99s\n   Dec(J2000) = -65d 30' 12.9\"\nwith an uncertainty of 3.5 arcseconds (radius, 90% containment). This\nlocation is 128 arcseconds from the BAT onboard position, within the\nBAT error circle. This position may be improved as more data are\nreceived; the latest position is available at\nhttps://www.swift.ac.uk/sper. \n\nA power-law fit to a spectrum formed from promptly downlinked event\ndata gives a column density in excess of the Galactic value (7.76 x\n10^20 cm^-2, Willingale et al. 2013), with an excess column of 5.3\n(+3.15/-2.74) x 10^21 cm^-2 (90% confidence). \n\nThe initial flux in the 2.5 s image was 1.57e-09 erg cm^-2 s^-1 (0.2-10\nkeV). \n\nUVOT took a finding chart exposure of 150 seconds with the White filter\nstarting 136 seconds after the BAT trigger. No credible afterglow candidate has\nbeen found in the initial data products. The 2.7'x2.7' sub-image covers 100% of\nthe XRT error circle. The typical 3-sigma upper limit has been about 19.6 mag. \nThe 8'x8' region for the list of sources generated on-board covers 100% of the\nXRT error circle. The list of sources is typically complete to about 18 mag. No\ncorrection has been made for the expected extinction corresponding to E(B-V) of\n0.075. \n\nThis source lies within the current (Sector 37) field-of-view of TESS camera 4. \n\nBurst Advocate for this burst is S. Laha (sib.laha AT gmail.com). \nPlease contact the BA by email if you require additional information\nregarding Swift followup of this burst. In extremely urgent cases, after\ntrying the Burst Advocate, you can contact the Swift PI by phone (see\nSwift TOO web site for information: http://www.swift.psu.edu/)",
  "circularId": 29828,
  "createdOn": 1618816290000,
  "email": "klp5@leicester.ac.uk",
  "subject": "GRB 210419A: Swift detection of a burst",
  "submitter": "Kim Page at U.of Leicester  <klp5@leicester.ac.uk>",
  "eventId": "GRB 210419A"
}