TITLE: GCN CIRCULAR NUMBER: 20807 SUBJECT: LIGO/Virgo G275697: Further Swift-XRT sources DATE: 17/03/03 15:57:15 GMT FROM: Phil Evans at U of Leicester P.A. Evans (U. Leicester), J.A. Kennea (PSU), S.D. Barthelmy (NASA/GSFC), A.P. Beardmore (U. Leicester), A.A. Breeveld (UCL-MSSL), D.N. Burrows (PSU), S. Campana (INAF-OAB), S.B. Cenko (NASA/GSFC), G. Cusumano (INAF-IASF PA), A. D'Ai (INAF-IASFPA), P. D'Avanzo (INAF-OAB), V.D'Elia(ASDC), P. Giommi (ASI), C. Gronwall (PSU), H.A. Krimm (CRESST/GSFC/USRA), N.P.M. Kuin (UCL-MSSL), A.Y. Lien (GSFC/UMBC), D. Malesani (DARK/NBI), F.E. Marshall (NASA/GSFC), A. Melandri (INAF-OAB), B. Mingo (U. Leicester), J.A. Nousek (PSU), S.R. Oates (U. Warwick), P.T. O'Brien (U. Leicester), J.P. Osborne (U. Leicester), C. Pagani (U. Leicester), K.L. Page (U.Leicester), D.M. Palmer (LANL), M. Perri (ASDC), J.L. Racusin (NASA/GSFC), B. Sbarufatti (INAF-OAB/PSU), M.H. Siegel (PSU), G. Tagliaferri (INAF-OAB), E. Troja (NASA/GSFC/UMCP) report on behalf of the Swift team: Swift has performed a series of 1372 observations of galaxies (from the 2MPZ catalogue) within the LVC error region for the GW trigger G275697, using the 'bayestar' GW localisation map. As this is a 3D skymap, galaxy distances were taken into account in selecting which ones to observe. The observations currently span from 15 ks to 256 ks after the LVC trigger, and cover 165 sq degrees on the sky (corrected for overlaps). This covers 0.16 of the probability in the LVC skymap, and 0.30 of the probability in the LVC map after convolving with the 2MPZ galaxy catalogue, as described by Evans et al., (2016, MNRAS, 462, 1591). Since the last Swift GCN, we have detected 6 X-ray sources, these are either new detections, or have been given a higher 'rank' than in the last circular. Each source is assigned a rank of 1-4 which describes how likely it is to be related to the GW trigger, with 1 being the most likely and 4 being the least likely. The ranks are described at http://www.swift.ac.uk/ranks.php. Source 14 was originally reported (in a COUNTERPART) notice as a rank 3 source, as no X-ray counterpart exists in the catalogues searched automatically. However, an object does exist in the latest 3XMM-DR6 release, which corresponds to source 14, so it has been re-classified as a rank 4, known source. Source 8 was also originally reported as rank 3 (LVC Circ. 20798), however it corresponds to a SIMBAD source 3C 33.1, which is a Seyfert 1, and has been detected by Chandra, therefore this has also been re-classified as rank 4. We have found: * 0 sources of rank 1 * 0 sources of rank 2 * 0 sources of rank 3 * 6 sources of rank 4 For all flux conversions and comparisons with catalogues and upper limits from other missions, we assumed a power-law spectrum with NH=3e20 cm^2, and photon index (Gamma)=1.7 RANK 4 sources ============== These are catalogued X-ray sources, showing no signs of outburst compared to previous observations, so they are not likely to be related to the GW trigger. Source 9: ============= RA: 331.2359 ( = 22h 04m 56.62s) J2000 Dec: +47.2357 ( = +47d 14' 08.5") J2000 Error: +5.5 (arcsec, radius, 90% confidence). Peak Rate: 1.5e-01 +/- 5.6e-02 ct/sec (0.3-10 keV) Peak Flux: 6.6e-12 +/- 2.4e-12 erg cm^-2 s^-1 (0.3-10 keV) Cat Source: 1SXPS J220456.4+471403 in the 1SXPS catalogue Separation: 5.4" from the XRT source Cat Rate: 5.8e-01 +/- 2.7e-02 ct/sec Cat Flux: 2.5e-11 +/- 1.2e-12 erg cm^-2 s^-1 (0.3-10 keV) so the source is not above the catalogued flux. There is no evidence for fading. NOTE: this source is NOT within 200 kpc of a GWGC or 2MPZ galaxy which is consistent (within 3-sigma) with the distance to the GW object. A SIMBAD object `V* HK Lac' is 4" away. There is 1 2MASS object within the source's 3-sigma error radius. NOTE: This source is affected by optical loading. The X-ray detection appears real, but the flux may be inaccurate. Source 10: ============= RA: 335.0282 ( = 22h 20m 6.77s) J2000 Dec: +49.5037 ( = +49d 30' 13.3") J2000 Error: +8.7 (arcsec, radius, 90% confidence). Peak Rate: 1.5e-01 +/- 5.9e-02 ct/sec (0.3-10 keV) Peak Flux: 6.6e-12 +/- 2.5e-12 erg cm^-2 s^-1 (0.3-10 keV) Cat Source: 1SXPS J222006.7+493011 in the 1SXPS catalogue Separation: 1.6" from the XRT source Cat Rate: 1.5e-01 +/- 1.1e-02 ct/sec Cat Flux: 6.5e-12 +/- 4.7e-13 erg cm^-2 s^-1 (0.3-10 keV) so the source is not above the catalogued flux. There is no evidence for fading. NOTE: this source is NOT within 200 kpc of a GWGC or 2MPZ galaxy which is consistent (within 3-sigma) with the distance to the GW object. A SIMBAD object `V* V383 Lac' is 3" away. There is 1 2MASS object within the source's 3-sigma error radius. Source 11: ============= RA: 149.3249 ( = 09h 57m 17.98s) J2000 Dec: -13.8334 ( = -13d 50' 00.2") J2000 Error: +6.1 (arcsec, radius, 90% confidence). Peak Rate: 2.5e-02 +/- 1.5e-02 ct/sec (0.3-10 keV) Peak Flux: 1.1e-12 +/- 6.4e-13 erg cm^-2 s^-1 (0.3-10 keV) Cat Source: 1RXS J095718.8-135031 in the ROSAT/RASSFSC catalogue Separation: 33.6" from the XRT source Cat Rate: 1.7e-02 +/- 8.0e-03 ct/sec Cat Flux: 4.9e-13 +/- 2.2e-13 erg cm^-2 s^-1 (0.3-10 keV) so the source is 0.8-sigma above the catalogued flux. The source may be fading, at the 0.3-sigma level. There are 2 GWGC or 2MPZ galaxies within 200 kpc of the source. and consistent (within 3-sigma) with the distance to the GW object. A SIMBAD object `3FGL J0957.5-1351' is 3.3" away. Source 12: ============= RA: 152.0125 ( = 10h 08m 3.00s) J2000 Dec: -14.9836 ( = -14d 59' 01.0") J2000 Error: +4.6 (arcsec, radius, 90% confidence). Peak Rate: 6.9e-02 +/- 4.1e-02 ct/sec (0.3-10 keV) Peak Flux: 3.0e-12 +/- 1.8e-12 erg cm^-2 s^-1 (0.3-10 keV) Cat Source: 1RXS J100802.7-145904 in the ROSAT/RASSBSC catalogue Separation: 5.4" from the XRT source Cat Rate: 2.9e-01 +/- 2.6e-02 ct/sec Cat Flux: 8.1e-12 +/- 7.4e-13 erg cm^-2 s^-1 (0.3-10 keV) so the source is not above the catalogued flux. The source may be fading, at the 0.9-sigma level. There is 1 GWGC or 2MPZ galaxy within 200 kpc of the source. and consistent (within 3-sigma) with the distance to the GW object. A SIMBAD object `2MASX J10080288-1459066' is 6" away. There are 2 2MASS objects within the source's 3-sigma error radius. Source 13: ============= RA: 150.9238 ( = 10h 03m 41.71s) J2000 Dec: -15.1337 ( = -15d 08' 01.3") J2000 Error: +5.6 (arcsec, radius, 90% confidence). Peak Rate: 7.2e-02 +/- 5.5e-02 ct/sec (0.3-10 keV) Peak Flux: 3.1e-12 +/- 2.4e-12 erg cm^-2 s^-1 (0.3-10 keV) Cat Source: 1RXS J100343.2-150820 in the ROSAT/RASSFSC catalogue Separation: 28.8" from the XRT source Cat Rate: 4.6e-02 +/- 1.3e-02 ct/sec Cat Flux: 1.3e-12 +/- 3.8e-13 erg cm^-2 s^-1 (0.3-10 keV) so the source is 0.8-sigma above the catalogued flux. The source may be fading, at the 1.1-sigma level. There are 2 GWGC or 2MPZ galaxies within 200 kpc of the source. and consistent (within 3-sigma) with the distance to the GW object. A SIMBAD object `[VV96] J100342.1-150808' is 8.2" away. There is 1 2MASS object within the source's 3-sigma error radius. Source 14: ============= RA: 0.1318 ( = 00h 00m 31.63s) J2000 Dec: +68.2501 ( = +68d 15' 00.4") J2000 Error: +4.9 (arcsec, radius, 90% confidence). Peak Rate: 2.8e-02 +/- 8.8e-03 ct/sec (0.3-10 keV) Peak Flux: 1.2e-12 +/- 3.8e-13 erg cm^-2 s^-1 (0.3-10 keV) Cat Source: in the catalogue Separation: 2.0" from the XRT source Cat Rate: 3.7e-01 +/- 7.8e-03 ct/sec Cat Flux: 9.9e-13 +/- 2.1e-14 erg cm^-2 s^-1 (0.3-10 keV) so the source is 0.6-sigma above the catalogued flux. There is no evidence for fading. There are 2 GWGC or 2MPZ galaxies within 200 kpc of the source. and consistent (within 3-sigma) with the distance to the GW object. A SIMBAD object `BD+67 1587' is 2" away. There is 1 2MASS object within the source's 3-sigma error radius. This circular is an official product of the Swift team.