{
  "bibcode": "2019GCN.25822....1J",
  "body": "Amruta Jaodand (Caltech), Sergio Campana (INAF/Brera), Murray Brightman\n(Caltech), Paolo D'Avanzo (INAF/Brera), Marianne Heida (Caltech), Fiona\nHarrison (Caltech), Giancarlo Ghirlanda (INAF/Brera), Mansi Kasliwal\n(Caltech), Kristin Madsen (Caltech), Kunal Mooley (Caltech), Maria Grazia\nBernardini (INAF/Brera), Andrea Melandri (INAF/Brera), Om Sharan Salafia\n(INAF/Brera), Ruben Salvaterra (INAF/IASF Milano)\n\nWe report on the Chandra X-ray follow-up of ASKAP J005547-270433 /\nAT2019osy, a candidate radio counterpart to GW190814bv (GCN 25324, 25621)\nidentified by Stewart et. al (GCN 25487) located at RA + 00:55:47.40  (13.948deg),\nDEC: -27:04:33.00 (-27.076deg). We have observed the field of AT2019osy ~ days \npost merger starting at 2019-09-22T21:33:50 UT with the Chandra X-ray telescope.\n\nEarlier, optical follow-up reported a source with i=22.3 (Andreoni et al.\nGCN 25488), spatially coincident with the radio source, and Palomar\n200-inch spectroscopic observations (Perley et al. GCN 25494) indicated\nthat the flux could be arising from AGN variability. Follow-up VLA and ATCA\nradio observations (Mooley et al. GCN 25539; Dobie et al. 25691) showed\nthat the radio flux did not continue increasing. Recent follow-up\nobservations carried out with ALMA reported a detection at 109 GHz,\nconsistent with the (RA 00:55:47.417, DEC -27:04:33.14) location reported\nby ASKAP, VLA and ATCA (Bauer et al. GCN 25801). An almost simultaneous HST\nobservation provided evidence for a small elongated nucleus at the host\ncenter, but not for a point source (Bauer et al. GCN 25801).\n\nThe Chandra observation failed to detect any X-ray source at the ASKAP\nJ005547-270433 / AT2019osy position. No sources in the close vicinity are\nalso apparent. A cross-match with the 2MASS archive shows a source should\nhave been present at the location of the radio candidate. We derive a 95\\%\n(0.3-8 keV) upper limit of 2.85e-4 counts/s. This converts to a 0.3-8 keV\nunabsorbed flux upper (nH=1.8e20 cm-2) limit of 3.2e-15 erg/cm2/s, assuming\na power law spectrum with photon index 1.66 (motivated by radio\nobservations, Dobie et al. GCN 25691), corresponding to a 0.3-8 keV\nunabsorbed luminosity of 4.2e40 erg/s.\n\nThe lack of detection of any X-ray activity at such a low level, indicates\nthat the emission of ASKAP J005547-270433 / AT 2019osy might not be due to\nthe nucleus of the host galaxy.\n\nWe thank Belinda Wilkes and the entire CXC staff for scheduling and\nenabling these observations at a rapid pace.\n\n\n[GCN OPS NOTE(24sep19): The extra header field was eliminated; the RA,DEC\nvalues were added into the first paragraph; and the signiture/contact block\nat the bottom of the CIrcualr was elimianted.]\n[GCN OPS NOTE(25sep19): Per author's request, the 25961 reference in the\nthird paragraph was changed from 25961 to 25691.]",
  "circularId": 25822,
  "createdOn": 1569260622000,
  "email": "amruta.jaodand@gmail.com",
  "subject": "LIGO/Virgo S190814bv: Chandra X-ray non-detection of ASKAP J005547-270433 / AT2019osy",
  "submitter": "Amruta Jaodand at Caltech  <amruta.jaodand@gmail.com>",
  "eventId": "LIGO/Virgo S190814bv"
}