{
  "bibcode": "2019GCN.24054....1D",
  "body": "P. D'Avanzo (INAF-OAB), J.A. Kennea (PSU), B. Sbarufatti\n(INAF-OAB/PSU), D.N. Burrows (PSU), J.P. Osborne (U. Leicester), K.L.\nPage (U. Leicester), A.P. Beardmore (U. Leicester), V. D'Elia (ASDC),\nA. D'Ai (INAF-IASFPA) and P.A. Evans (U. Leicester) report on behalf of\nthe Swift-XRT team:\n\nSwift-XRT has performed follow-up observations of the MAXI-detected\nburst GRB 190404C (Yamada et al. 2019, GCN circ. 24049)in a series of\nobservations tiled on the sky. The total exposure time is 4.9 ks,\ndistributed over 4 tiles; the maximum exposure at a single sky location\nwas 3.4 ks. The data were collected between T0+7.4 ks and T0+19.1 ks,\nand are entirely in Photon Counting (PC) mode. \n\nThree uncatalogued X-ray sources have been detected, however none of\nthem is above the RASS limit. No source shows definitive signs of\nfading, despite Source 3, which is the brightest, marginally weakened\n(at the 2.7 sigma level) during the observation. Therefore, at the\npresent time we cannot safely identify the afterglow. Details of these\nsources are given below:\n\nSource 1:\n  RA (J2000.0):  221.0760  =  14:44:18.23\n  Dec (J2000.0): -22.6488  =  -22:38:55.5\n  Error: 6.1 arcsec (radius, 90% conf.)\n  Count-rate: (6.3 [+3.2, -2.4])e-3 ct s^-1   \n  Distance: 1015 arcsec from MAXI position.\n  Flux: (3.0 [+1.5, -1.1])e-13 erg cm^-2 s^-1 (observed, 0.3-10 keV)\n\nSource 2:\n  RA (J2000.0):  221.0110  =  14:44:2.63\n  Dec (J2000.0): -22.5140  =  -22:30:50.3\n  Error: 13.5 arcsec (radius, 90% conf.)\n  Count-rate: (6.8 [+3.8, -2.8])e-3 ct s^-1   \n  Distance: 1006 arcsec from MAXI position.\n  Flux: (5.4 [+3.0, -2.2])e-13 erg cm^-2 s^-1 (observed, 0.3-10 keV)\n\nSource 3:\n  RA (J2000.0):  220.84256  =  14:43:22.21\n  Dec (J2000.0): -22.66386  =  -22:39:49.9\n  Error: 2.8 arcsec (radius, 90% conf. [Enhanced position])\n  Count-rate: 0.0236 [+0.0041, -0.0038] ct s^-1   \n  Distance: 245 arcsec from MAXI position.\n  Flux: (5.99 [+1.03, -0.98])e-13 erg cm^-2 s^-1 (observed, 0.3-10 keV)\n\n\nWe do not find any X-ray object at the position of the optical\ncandidate reported by Waratkar et al. 2019 (GCN circ. 24051), the\nclosest source being Source 1 at a distance of 4.3 arcmin. The XRT\nupper limit at the position of the GROWTH candidate is ~7e-3 ct s^-1.\nThe UVOT upper limit at the same position is ~ 21 mag in the U band.\n\nThe results of the XRT-team automatic analysis of the tiled XRT\nobservations, including a position-specific upper limit calculator, are\navailable at http://www.swift.ac.uk/xrt_products/TILED_GRB00079.\n\nThis circular is an official product of the Swift-XRT team.",
  "circularId": 24054,
  "createdOn": 1554477379000,
  "email": "valerio.delia@ssdc.asi.it",
  "subject": "GRB 190404C: Swift-XRT observations",
  "submitter": "Valerio D'Elia at ASDC  <valerio.delia@ssdc.asi.it>",
  "eventId": "GRB 190404C"
}