{
  "editedBy": "Judith Racusin at NASA/GSFC <judith.racusin@nasa.gov> on behalf of Amy Lien at GSFC <amy.y.lien@nasa.gov>",
  "eventId": "GRB 261011A",
  "editedOn": 1791731831449,
  "eventType": [],
  "circularId": 45896,
  "createdOn": 1791728450646,
  "submittedHow": "email",
  "version": 2,
  "format": "text/plain",
  "submitter": "Jimmy DeLaunay at PSU <jjd330@psu.edu>",
  "subject": "GRB 261011A: Swift detection of an unusual burst",
  "body": "S. B. Cenko (GSFC), S. D. Barthelmy (GSFC), S. Dichiara (PSU),\nR. Gupta (NASA GSFC), N. P. M. Kuin (UCL-MSSL), A. Y. Lien (U Tampa),\nM. J. Moss (GSFC), K. L. Page (U Leicester), D. M. Palmer (LANL), \nand M. H. Siegel (PSU) report on behalf of the Neil Gehrels Swift Observatory Team:\n\nAt 13:46:41 UT, the Swift Burst Alert Telescope (BAT) triggered and\nlocated GRB 261011A (trigger=1516664).  Swift slewed immediately to the burst.\nThe BAT on-board calculated location is \nRA, Dec 21.925, -21.529 which is \n   RA(J2000) = 01h 27m 42s\n   Dec(J2000) = -21d 31' 42\"\nwith an uncertainty of 3 arcmin (radius, 90% containment, including \nsystematic uncertainty).  The BAT light curve showed a broad soft pulse \nfrom T0 to T0+130 sec and a shoulder extending out to T0+260 sec for a total \nduration of about 260 sec.  The peak count rate was ~8000 counts/sec \n(15-350 keV), at ~95 sec after the trigger.\n\nThe XRT began observing the field at 13:51:57.1 UT, 315.8 seconds after\nthe BAT trigger. No source was detected in the 2.5-s promptly available\nimage. We are waiting for the full dataset to detect and localise the\nXRT counterpart.\n\nUVOT took a finding chart exposure of nominal 150.000 seconds with the White\nfilter starting 321 seconds after the BAT trigger. There is a candidate\nafterglow in the list of sources generated on-board at\n  RA(J2000)  =\t01:27:35.39 =  21.89746\n  DEC(J2000) = -21:33:37.2  = -21.56032\nwith a 90%-confidence error radius of about 1.10 arc sec. This position is\n145.7 arc sec. from the center of the BAT error circle. The estimated magnitude\nis 17.78. No correction has been made for extinction.\n\nThe BAT lightcurve is very unusual in that it combines a 260 second long\nlow energy emission mostly below 50 keV, with a ~5 second short peak\nstructure around T+95 seconds visible at all energies up the to 100-350 keV band.\n\nBurst Advocate for this burst is S. B. Cenko (brad.cenko AT nasa.gov).\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/)\n\n"
}