TITLE: GCN CIRCULAR NUMBER: 21930 SUBJECT: IceCube-170922A: Swift-XRT observations DATE: 17/09/26 14:34:30 GMT FROM: Azadeh Keivani at PSU A. Keivani (PSU), P.A. Evans (U. Leicester), J.A. Kennea (PSU), D.B. Fox (PSU), D.F. Cowen (PSU), J.P. Osborne (U. Leicester), and F.E. Marshall (GSFC) report on behalf of the Swift-IceCube collaboration: Swift has observed the field of the IceCube EHE event, IceCube-170922A (revision 0, https://gcn.gsfc.nasa.gov/notices_amon/50579430_130033.amon), utilizing the on-board 19-point tiling pattern to cover a region centred on RA,Dec (J2000) = (77.2866d, +5.7537d), with a radius of approximately 0.8 degrees. Swift-XRT collected ~800 s per field of PC mode data per tile. The observations were taken between 00:09:16 UT and 22:42:08 UT on 2017 September 23 (i.e. from 11.7 ks to 92.9 ks after the neutrino trigger), and covered 2.1 square degrees. Nine X-ray sources are detected in the observations. Eight of these correspond to known X-ray emitters. One object (Source 6) is not catalogued in X-rays, however it lies 5.7" from PMN J0511+0538 which is a radio source. The X-ray source position is RA,Dec (J2000) = (77.8658d, +5.6420d) which is equivalent to: RA = 05h 11m 27.80s Dec = +05d 38' 31.2" with an uncertainty of 7.1" [90% confidence radius]. The mean XRT count rate is 6.9 (+3.7, -2.8) e-3 ct s^-1. More XRT follow-up observations have been requested. The 3-sigma upper limit on the count rate in the rest of the field is 0.0093 ct s^-1, which corresponds to a 0.3-10 keV flux of 3.8e-13 erg cm^-2 s^-1 for a typical AGN spectrum (NH=3e20 cm^-2, Gamma=1.7). Overlaps between the different tiles account for 0.5 square degrees: in these regions the 3-sigma upper limit is 0.0057 ct s^-1, corresponding to 2.3e-13 erg cm^-2 s^-1. Source 1: ============= RA: 76.7226 ( = 05h 06m 53.42s) J2000 Dec: +6.1154 ( = +06d 06' 55.4") J2000 Error: +4.3 (arcsec, radius, 90% confidence). Peak Rate: 5.6e-02 +/- 1.4e-02 ct/sec (0.3-10 keV) Peak Flux: 2.3e-12 +/- 5.7e-13 erg cm^-2 s^-1 (0.3-10 keV) Cat Source: 1RXS J050653.3+060648 in the ROSAT/RASSBSC catalogue Separation: 7.6" from the XRT source Cat Rate: 1.2e-01 +/- 2.0e-02 ct/sec Cat Flux: 1.8e-12 +/- 3.0e-13 erg cm^-2 s^-1 (0.3-10 keV) A SIMBAD object `TYC 110-755-1' is 3.6" away. Source 2: ============= RA: 77.3571 ( = 05h 09m 25.70s) J2000 Dec: +5.6924 ( = +05d 41' 32.6") J2000 Error: +4.2 (arcsec, radius, 90% confidence). Peak Rate: 9.3e-02 +/- 2.1e-02 ct/sec (0.3-10 keV) Peak Flux: 3.8e-12 +/- 8.6e-13 erg cm^-2 s^-1 (0.3-10 keV) Cat Source: 1SXPS J050925.9+054134 in the 1SXPS catalogue Separation: 4.7" from the XRT source Cat Rate: 3.9e-02 +/- 2.6e-03 ct/sec Cat Flux: 1.7e-12 +/- 1.1e-13 erg cm^-2 s^-1 (0.3-10 keV) A SIMBAD object `QSO J0509+0541' is 4.8" away. Source 3: ============= RA: 77.6614 ( = 05h 10m 38.74s) J2000 Dec: +5.9082 ( = +05d 54' 29.5") J2000 Error: +5.1 (arcsec, radius, 90% confidence). Peak Rate: 1.5e-02 +/- 4.1e-03 ct/sec (0.3-10 keV) Peak Flux: 6.2e-13 +/- 1.7e-13 erg cm^-2 s^-1 (0.3-10 keV) Cat Source: 1RXS J051038.6+055432 in the ROSAT/RASSBSC catalogue Separation: 3.8" from the XRT source Cat Rate: 5.9e-02 +/- 1.4e-02 ct/sec Cat Flux: 1.7e-12 +/- 4.0e-13 erg cm^-2 s^-1 (0.3-10 keV) A SIMBAD object `2MASS J05103912+0554261' is 6.7" away. Source 4: ============= RA: 77.1391 ( = 05h 08m 33.38s) J2000 Dec: +5.5188 ( = +05d 31' 07.7") J2000 Error: +5.5 (arcsec, radius, 90% confidence). Peak Rate: 1.7e-01 +/- 1.3e-01 ct/sec (0.3-10 keV) Peak Flux: 7.0e-12 +/- 5.3e-12 erg cm^-2 s^-1 (0.3-10 keV) Cat Source: XMMSL2 J050833.1+053121 in the XMM-NEWTON/XMMSLEWCLN catalogue Separation: 13.5" from the XRT source Cat Rate: 6.9e-01 +/- 2.9e-01 ct/sec Cat Flux: 6.1e-12 +/- 2.6e-12 erg cm^-2 s^-1 (0.3-10 keV) Source 5: ============= RA: 77.4264 ( = 05h 09m 42.34s) J2000 Dec: +5.7826 ( = +05d 46' 57.4") J2000 Error: +5.3 (arcsec, radius, 90% confidence). Peak Rate: 1.7e-02 +/- 6.4e-03 ct/sec (0.3-10 keV) Peak Flux: 7.0e-13 +/- 2.6e-13 erg cm^-2 s^-1 (0.3-10 keV) Cat Source: 1SXPS J050942.4+054655 in the 1SXPS catalogue Separation: 2.0" from the XRT source Cat Rate: 7.2e-03 +/- 1.2e-03 ct/sec Cat Flux: 3.1e-13 +/- 5.2e-14 erg cm^-2 s^-1 (0.3-10 keV) A SIMBAD object `HD 33326' is 2.1" away. Source 7: ============= RA: 77.1531 ( = 05h 08m 36.74s) J2000 Dec: +5.2053 ( = +05d 12' 19.1") J2000 Error: +6.0 (arcsec, radius, 90% confidence). Peak Rate: 2.5e-02 +/- 7.0e-03 ct/sec (0.3-10 keV) Peak Flux: 1.0e-12 +/- 2.9e-13 erg cm^-2 s^-1 (0.3-10 keV) Cat Source: XMMSL2 J050836.8+051224 in the XMM-NEWTON/XMMSLEWCLN catalogue Separation: 4.7" from the XRT source Cat Rate: 9.5e-01 +/- 4.1e-01 ct/sec Cat Flux: 9.5e-12 +/- 4.1e-12 erg cm^-2 s^-1 (0.3-10 keV) A SIMBAD object `V* V1848 Ori' is 5.8" away. Source 8: ============= RA: 77.2410 ( = 05h 08m 57.84s) J2000 Dec: +6.4408 ( = +06d 26' 26.9") J2000 Error: +5.9 (arcsec, radius, 90% confidence). Peak Rate: 3.0e-02 +/- 8.1e-03 ct/sec (0.3-10 keV) Peak Flux: 1.2e-12 +/- 3.3e-13 erg cm^-2 s^-1 (0.3-10 keV) Cat Source: 1RXS J050857.4+062633 in the ROSAT/RASSBSC catalogue Separation: 9.3" from the XRT source Cat Rate: 1.2e-01 +/- 1.8e-02 ct/sec Cat Flux: 2.5e-12 +/- 3.9e-13 erg cm^-2 s^-1 (0.3-10 keV) A SIMBAD object `1RXS J050857.4+062633' is 7.9" away. Source 9: ============= RA: 77.4368 ( = 05h 09m 44.83s) J2000 Dec: +5.3639 ( = +05d 21' 50.0") J2000 Error: +5.7 (arcsec, radius, 90% confidence). Peak Rate: 1.4e-02 +/- 5.0e-03 ct/sec (0.3-10 keV) Peak Flux: 5.7e-13 +/- 2.0e-13 erg cm^-2 s^-1 (0.3-10 keV) Cat Source: 1RXS J050944.9+052219 in the ROSAT/RASSFSC catalogue Separation: 28.9" from the XRT source Cat Rate: 2.1e-02 +/- 9.5e-03 ct/sec Cat Flux: 2.3e-13 +/- 1.1e-13 erg cm^-2 s^-1 (0.3-10 keV)