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GCN Circular 26479

Subject
LIGO/Virgo S191216ap: CORRECTED list of galaxies coincident with LIGO/Virgo and HAWC positions
Date
2019-12-17T19:10:25Z (4 years ago)
From
Leo Singer at GSFC <leo.p.singer@nasa.gov>
L. Singer (GSFC), T. Ahumada (UMD), S. Anand (Caltech), J. S. Bloom
(UCB), M. M. Kasliwal (Caltech), H. Kumar (IITB), A. Sagu��s Carracedo
(OKC, Stockholm University), I. Andreoni (Caltech), V. Bhalerao
(IITB) report on behalf of the GROWTH collaboration:

Reanalysing the data used in GCN 26476, we provide a revised galaxy
list.

We cross-matched the LIGO/Virgo localization (GCN 26454) 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. We find nine
matching galaxies, all of which are also in SDSS.

The distance parameters from the BAYESTAR localization at the
position of the HAWC candidate are DISTMU = 233.78 Mpc, DISTSIGMA =
63.57 Mpc. The mean and standard deviation of distance in this
direction are DISTMEAN = 265.97 Mpc, DISTSTD = 59.68 Mpc, and the
median distance in this direction is 265.40 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 |
| ---------- | --------- | ----- |-------- | ---------- |
| 323.482422 | +5.279632 | 274.4 | 86      | 0.23       |
| 323.056030 | +4.832057 | 219.1 | 72      | 2.06       |
| 322.921936 | +5.503483 | 232.2 | 72      | 2.21       |
| 322.838806 | +5.255421 | 179.3 | 73      | 2.30       |
| 322.821228 | +5.553754 | 338.7 | 81      | 2.59       |
| 322.749084 | +5.108610 | 330.8 | 78      | 2.62       |
| 323.173767 | +4.467985 | 292.5 | 88      | 2.80       |
| 322.906006 | +5.850705 | 323.1 | 85      | 2.93       |
| 323.034882 | +4.482058 | 340.7 | 86      | 2.99       |

We highlight the first galaxy in this list since it is consistent
with both LIGO/Virgo 3D localization and the HAWC 1-sigma angular
separation. There is no evidence for significant variability of
within this galaxy in either PTF or ZTF.

Follow-up of these galaxies is encouraged. Further analysis is
ongoing.

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.
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