TITLE:   GCN CIRCULAR
NUMBER:  26507
SUBJECT: LIGO/Virgo S191216ap: UPDATED list of galaxies coincident with LIGO/Virgo LALInference skymap and HAWC positions
DATE:    19/12/20 04:18:37 GMT
FROM:    Shreya Anand at GROWTH Caltech  <sanand@caltech.edu>

T. Ahumada (UMD), S. Anand (Caltech), and L.P. Singer (NASA-GSFC) report on behalf of the GROWTH collaboration:

Based on the new LALInference map (GCN 26505), we re-ran our galaxy cross-match from GCN 26479 with the HAWC position (GCN 26472)and the GLADE v2.3 catalog (Dalya et al., 2018), to identify sources within the 90% LIGO/Virgo credible volume and within a 3-sigma radius of the HAWC candidate. Our updated search yields only three matching galaxies, which were in our previously reported list of galaxies (GCN 26479). All of the galaxies in our previous list are within the 95% 3D credible level in the LALInference map; we report only those galaxies still within the 90% 3D credible level.

The distance parameters from the LALInference localization at the
position of the HAWC candidate are DISTMU= 272.35 Mpc and DISTSIGMA= 44.52 Mpc.

In the table below, we give the right ascensions and declinations in
degrees and luminosity distances in Mpc. The "GW C.L." column
provides the LIGO/Virgo 3D credible level within which the galaxy is
found (smaller values mean more consistent with the GW position). The
"HAWC sigma" column gives the separation from the HAWC position,
divided by the HAWC 1-sigma error radius.

| RAJ2000    | DEJ2000   | Dist  | GW C.L. | HAWC sigma |
| ---------- | --------- | ----- |-------- | ---------- |
| 322.821228 | +5.553754 | 338.7 | 81      | 2.59       |
| 322.749084 | +5.108610 | 330.8 | 78      | 2.62       |
| 323.034882 | +4.482058 | 340.7 | 86      | 2.99       |

GROWTH is a worldwide collaboration comprising of Caltech, USA; IPAC,
USA; WIS, Israel; OKC, Sweden; JSI/UMD, USA; U Washington, USA; DESY,
Germany; MOST, Taiwan; UW Milwaukee, USA; LANL USA; Tokyo Tech,
Japan; IITB, India; IIA, India; LJMU, UK; TTU, USA; SDSU, USA and
USyd, Australia. ZTF acknowledges the generous support of the NSF
under AST MSIP Grant No 1440341. GROWTH acknowledges generous support
of the NSF under PIRE Grant No 1545949.