{
  "bibcode": "2016GCN.18870....1E",
  "body": "P.A. Evans (U. Leicester), J.A. Kennea (PSU), S.D. Barthelmy\n(NASA/GSFC), D.N. Burrows (PSU), S. Campana (INAF-OAB), S.B. Cenko\n(NASA/GSFC), N. Gehrels (NASA/GSFC), P. Giommi (ASI), F.E. Marshall\n(NASA/GSFC), J.A. Nousek (PSU), P.T. O'Brien (U. Leicester), J.P.\nOsborne (U. Leicester), D.M. Palmer (LANL), M. Perri (ASDC), J.L.\nRacusin (NASA/GSFC), M.H. Siegel (PSU), G. Tagliaferri (INAF-OAB)\nreport on behalf of the Swift team:\n\nSwift has performed a series of 264 observations of galaxies (from the\nGWGC catalogue) within the aLIGO error region for the aLIGO trigger\nG211117, using the 'bayestar' GW localisation map. The observations\ncurrently span from 140 ks to 1677 ks after the aLIGO trigger, and\ncover 32.3 sq degrees on the sky (corrected for overlaps).\n\nSince the last Swift GCN, we have detected 8 X-ray sources, these are\neither new detections, or have been given a higher 'rank' than in the\nlast circular. Each source is assigned a rank of 1-4 which describes\nhow likely it is to be related to the GW trigger, with 1 being the most\nlikely and 4 being the least likely. The ranks are described at\nhttp://www.swift.ac.uk/ranks.php.\n\nWe have found:\n\n  * 0 sources of rank 1\n  * 0 sources of rank 2\n  * 6 sources of rank 3\n  * 2 sources of rank 4\n\nWe assumed a power-law spectrum with NH=3e20 cm^2, and photon index\n(Gamma)=1.7\n\nSeveral other sources were circulated as GCN/LVC Counterpart notices\n(including one with a rank of 2) with a flag identifying them as\npotentially spurious. Manual inspection of the images confirms that\nthese were not point sources, but artifacts caused by an area of\ndiffuse X-ray emission, centred on RA~02h 32m 37s Dec~+18d 44' 10\",\nwith a radius of ~0.6 arcmin.\n\nRANK 3 sources\n==============\n\nThese are uncatalogued X-ray sources, however they are not brighter\nthan previous upper limits, so do not stand out as likely counterparts\nto the GW trigger.\n  \n  Source 56:\n  =============\n    RA: \t 38.0971 ( = 02h 32m 23.30s) J2000\n    Dec:\t +18.5781 ( = +18d 34' 41.2\") J2000\n    Error:\t +5.9 (arcsec, radius, 90% confidence).\n    Peak Rate:\t 2.2e-03 +/- 6.4e-04 ct/sec (0.3-10 keV)\n    Peak Flux:\t 9.5e-14 +/- 2.7e-14 erg cm^-2 s^-1 (0.3-10 keV)\n    RASS UL:\t 1.2e-01 ct/sec, 3-sigma, converted to XRT (0.3-10 keV)\n\n       so the source is not above the RASS 3-sigma upper limit.\n    There is no evidence for fading.\n    NOTE: this source is not within 200 kpc of a GWGC galaxy.\n  \n  Source 57:\n  =============\n    RA: \t 38.0905 ( = 02h 32m 21.72s) J2000\n    Dec:\t +18.6325 ( = +18d 37' 57.0\") J2000\n    Error:\t +6.8 (arcsec, radius, 90% confidence).\n    Peak Rate:\t 3.1e-03 +/- 8.1e-04 ct/sec (0.3-10 keV)\n    Peak Flux:\t 1.3e-13 +/- 3.5e-14 erg cm^-2 s^-1 (0.3-10 keV)\n    RASS UL:\t 1.4e-01 ct/sec, 3-sigma, converted to XRT (0.3-10 keV)\n\n       so the source is not above the RASS 3-sigma upper limit.\n    There is no evidence for fading.\n    NOTE: this source is not within 200 kpc of a GWGC galaxy.\n  \n  Source 59:\n  =============\n    RA: \t 38.1497 ( = 02h 32m 35.93s) J2000\n    Dec:\t +18.7140 ( = +18d 42' 50.4\") J2000\n    Error:\t +7.6 (arcsec, radius, 90% confidence).\n    Peak Rate:\t 1.0e-03 +/- 4.4e-04 ct/sec (0.3-10 keV)\n    Peak Flux:\t 4.4e-14 +/- 1.9e-14 erg cm^-2 s^-1 (0.3-10 keV)\n    RASS UL:\t 8.1e-02 ct/sec, 3-sigma, converted to XRT (0.3-10 keV)\n\n       so the source is not above the RASS 3-sigma upper limit.\n    There is no evidence for fading.\n    NOTE: this source is not within 200 kpc of a GWGC galaxy.\n  \n  Source 61:\n  =============\n    RA: \t 38.2965 ( = 02h 33m 11.16s) J2000\n    Dec:\t +18.5393 ( = +18d 32' 21.5\") J2000\n    Error:\t +11.5 (arcsec, radius, 90% confidence).\n    Peak Rate:\t 1.1e-03 +/- 4.6e-04 ct/sec (0.3-10 keV)\n    Peak Flux:\t 4.8e-14 +/- 2.0e-14 erg cm^-2 s^-1 (0.3-10 keV)\n    RASS UL:\t 6.1e-02 ct/sec, 3-sigma, converted to XRT (0.3-10 keV)\n\n       so the source is not above the RASS 3-sigma upper limit.\n    There is no evidence for fading.\n    NOTE: this source is not within 200 kpc of a GWGC galaxy.\n  \n  Source 65:\n  =============\n    RA: \t 38.1408 ( = 02h 32m 33.79s) J2000\n    Dec:\t +18.6392 ( = +18d 38' 21.1\") J2000\n    Error:\t +7.6 (arcsec, radius, 90% confidence).\n    Peak Rate:\t 1.3e-03 +/- 5.1e-04 ct/sec (0.3-10 keV)\n    Peak Flux:\t 5.7e-14 +/- 2.2e-14 erg cm^-2 s^-1 (0.3-10 keV)\n    RASS UL:\t 9.0e-02 ct/sec, 3-sigma, converted to XRT (0.3-10 keV)\n\n       so the source is not above the RASS 3-sigma upper limit.\n    There is no evidence for fading.\n    NOTE: this source is not within 200 kpc of a GWGC galaxy.\n  \n  Source 67:\n  =============\n    RA: \t 38.0820 ( = 02h 32m 19.68s) J2000\n    Dec:\t +18.7338 ( = +18d 44' 01.7\") J2000\n    Error:\t +5.9 (arcsec, radius, 90% confidence).\n    Peak Rate:\t 1.2e-03 +/- 5.1e-04 ct/sec (0.3-10 keV)\n    Peak Flux:\t 5.2e-14 +/- 2.2e-14 erg cm^-2 s^-1 (0.3-10 keV)\n    RASS UL:\t 1.3e-01 ct/sec, 3-sigma, converted to XRT (0.3-10 keV)\n\n       so the source is not above the RASS 3-sigma upper limit.\n    There is no evidence for fading.\n    NOTE: this source is not within 200 kpc of a GWGC galaxy.\n\n\nRANK 4 sources\n==============\n\nThese are catalogued X-ray sources, showing no signs of outburst\ncompared to previous observations, so they are not likely to be related\nto the GW trigger.\n  \n  Source 63:\n  =============\n    RA: \t 136.1544 ( = 09h 04m 37.06s) J2000\n    Dec:\t +55.5974 ( = +55d 35' 50.6\") J2000\n    Error:\t +6.9 (arcsec, radius, 90% confidence).\n    Peak Rate:\t 1.5e-01 +/- 5.9e-02 ct/sec (0.3-10 keV)\n    Peak Flux:\t 6.5e-12 +/- 2.5e-12 erg cm^-2 s^-1 (0.3-10 keV)\n    Cat Source:  1SXPS J090436.8+553600 in the 1SXPS catalogue\n    Separation:  10.3\" from the XRT source\n    Cat Rate:\t 1.7e-01 +/- 4.0e-03 ct/sec (0.3-10 keV)\n    Cat Flux:\t 7.2e-12 +/- 1.7e-13 erg cm^-2 s^-1 (0.3-10 keV)\n       so the source is not above the catalogued flux.\n    There is no evidence for fading.\n    NOTE: this source is not within 200 kpc of a GWGC galaxy.\n    A SIMBAD object `2MASX J09043675+5535515' is 2.7\" away.\n    There is 1 2MASS object within the source's 3-sigma error radius.\n  \n  Source 64:\n  =============\n    RA: \t 153.7665 ( = 10h 15m 3.96s) J2000\n    Dec:\t +49.4331 ( = +49d 25' 59.2\") J2000\n    Error:\t +5.0 (arcsec, radius, 90% confidence).\n    Peak Rate:\t 2.0e+00 +/- 4.4e-01 ct/sec (0.3-10 keV)\n    Peak Flux:\t 8.5e-11 +/- 1.9e-11 erg cm^-2 s^-1 (0.3-10 keV)\n    Cat Source:  1SXPS J101504.1+492559 in the 1SXPS catalogue\n    Separation:  1.7\" from the XRT source\n    Cat Rate:\t 1.3e+00 +/- 7.7e-03 ct/sec (0.3-10 keV)\n    Cat Flux:\t 5.6e-11 +/- 3.3e-13 erg cm^-2 s^-1 (0.3-10 keV)\n       so the source  is 1.5-sigma above the catalogued flux.\n    There is no evidence for fading.\n    NOTE: this source is not within 200 kpc of a GWGC galaxy.\n    A SIMBAD object `6C 101157+494057' is 2.3\" away.\n    There is 1 2MASS object within the source's 3-sigma error radius.\n\nThis circular is an official product of the Swift team.",
  "circularId": 18870,
  "createdOn": 1452860410000,
  "email": "pae9@leicester.ac.uk",
  "eventId": "LIGO/Virgo G211117",
  "subject": "LIGO/Virgo G211117: Further Swift-XRT sources",
  "submitter": "Phil Evans at U of Leicester  <pae9@leicester.ac.uk>"
}