{
  "bibcode": "2016GCN.19747....1E",
  "body": "P.A. Evans (U. Leicester), J.A. Kennea (PSU), A. Keivani (PSU), D.B. Fox\n(PSU), G. Tesic (PSU), D.F. Cowen (PSU), J.P. Osborne (U. Leicester),\nM.W.E. Smith (JPL) and F.E. Marshall (GSFC) report on behalf of the\nSwift-IceCube collaboration:\n\nSwift has observed the field of the IceCube HESE event IceCube-160731A,\n\"AMON ICECUBE HESE 128290 6888376\" (revision 0), utilising the on-board\n19-point tiling pattern to cover a region centred on RA,Dec (J2000) =\n(215.109, -0.458), with a radius of approximately 0.8 degrees. Swift-XRT\ncollected ~800 s per field of PC mode data per tile. The observations\nwere taken between 03:00:46 and 14:51:52 on 2016 Jul 31 (i.e. from\n3.9 ks to 46.5 ks after the neutrino trigger), and covered 2.1\nsquare degrees.\n\nSix X-ray sources are detected in the observations. All of these\ncorrespond either to known X-ray emitters, or to objects catalogued\n(e.g. in SIMBAD) and from which X-rays may be expected. Therefore, we\nconclude that we have not discovered a transient X-ray event associated\nwith the IceCube trigger. The 3-sigma upper limit on the count rate in\nthe rest of the field is 0.01 ct s^-1, which corresponds to a 0.3-10 keV\nflux of 4.3e-13 erg cm^-2 s^-1 for a typical AGN spectrum (NH=3e20\ncm^-2, Gamma=1.7). Overlaps between the different tiles accounts for 0.5\nsquare degrees: in these regions the 3-sigma upper limit is 0.0071 ct\ns^-1, corresponding to 3.1e-13 erg cm^-2 s^-1.\n\nNo transient sources were detected in the UVOT data, down to a 3-sigma\nupper limit of 18.0, in the u filter.\n\nDetails of the six detected X-ray sources are below. All fluxes are\n0.3-10 keV and assume the same AGN spectrum as above.\n\nSource 1\n========\nRA:          14h 22m 46.57s = 215.69403d \t\nDec:         -00d 38' 16.0\" = -0.63777d\nError:       4.2 arcsec (90% confidence radius)\nCount rate:  (1.7 +/- 0.4) x 10^-2 ct s^-1\nFlux:        (7.3 +/- 1.7) x 10^-13 erg cm^-2 s^-1\nNotes:       This source is 2.4\" from HD 125981 which SIMBAD lists as an\n              A0IV star (classified by the Michigan Spectral Survey).\n              This detection may not be due to an X-ray source, but due\n              to the bright (V = 6.7) stellar optical flux.\n\n\nSource 2\n========\nRA:          14h 19m 36.50s = 214.90209d \t\nDec:         -01d 08' 45.3\" = -0.14592d\nError:       4.9 arcsec (90% confidence radius)\nCount rate:  (1.3 +/- 0.6) x 10^-2 ct s^-1\nFlux:        (5.6 +/- 2.6) x 10^-13 erg cm^-2 s^-1\nNotes:       This source is 6.5\" from [VV2006] J141936.0-010840 which\n              SIMBAD lists as a quasar.\n\nSource 3\n========\nRA:          14h 22m 53.44s = 215.72267d \t\nDec:         -00d 01' 50.7\"  = -0.03074d\nError:       5.9 arcsec (90% confidence radius)\nCount rate:  (2.2 +/- 0.7) x 10^-2 ct s^-1\nFlux:        (9.5 +/- 3.0) x 10^-13 erg cm^-2 s^-1\nNotes:       This source is 2.2\" from QSO J1422-0001 which SIMBAD lists\n              as a quasar, and 3.1\" from the known X-ray source,\n              3XMM J142253.3-000149. The observed  X-ray flux is\n              consistent with the flux in the 3XMM catalogue.\n\nSource 4\n========\nRA:          14h 22m 53.44s = 215.72267d\nDec:         -00d 36' 00.1\"  = -0.60004d\nError:       8.1 arcsec (90% confidence radius)\nCount rate:  (6.7 +/- 3.2) x 10^-3 ct s^-1\nFlux:        (2.9 +/- 1.4) x 10^-13 erg cm^-2 s^-1\nNotes:       This source has been previously detected by Swift\n              (1SXPS J142252.8-003553) and the observed flux is\n              consistent with the catalogued values.\n\nSource 5\n========\nRA:          14h 19m 50.15s = 214.95898\nDec:         -00d 06' 45.6\" = -0.11266d\nError:       5.5 arcsec (90% confidence radius)\nCount rate:  (1.5 +/- 0.6) x 10^-2 ct s^-1\nFlux:        (6.5 +/- 2.6) x 10^-13 erg cm^-2 s^-1\nNotes:       This source is 2.3\" from [VV2006] J141949.9-000644 which\n              SIMBAD lists as a quasar.\n\nSource 6\n========\nRA:          14h 19m 50.15s = 214.61169d\nDec:         -00d 06' 45.6\" = 0.24144d\nError:       6.6 arcsec (90% confidence radius)\nCount rate:  (1.5 +/- 0.7) x 10^-2 ct s^-1\nFlux:        (6.5 +/- 3.0) x 10^-13 erg cm^-2 s^-1\nNotes:       This source is 2.3\" from 2MASS J14182661+0014283, which\n              appears to be a late-type star.",
  "circularId": 19747,
  "createdOn": 1470063623000,
  "email": "pae9@leicester.ac.uk",
  "subject": "Swift follow up of IceCube-160731A",
  "submitter": "Phil Evans at U of Leicester  <pae9@leicester.ac.uk>",
  "eventId": "IceCube-160731A"
}