GCN Circular 33820

David O. Cook (Caltech/IPAC), Rick Ebert (Caltech/IPAC), George Helou (Caltech/IPAC), Joseph M. Mazzarella (Caltech/IPAC), Marion Schmitz (Caltech/IPAC), and Leo Singer (NASA/GSFC)

On behalf of the NASA/IPAC Extragalactic Database (NED) Team.

We spatially cross-matched the LVK S230518h-3-Update sky localization with the NED Local Volume Sample (NED-LVS; Cook et al. 2023 submitted), which is a subset of NED with a redshift or redshift-independent distance less than 1000 Mpc. We find 6336 galaxies within the 90% containment volume, and we list here the top 20 galaxies located in the 90% volume sorted by the joint probability of the 3D localization and the WISE W1 luminosity (an observable proxy for stellar mass). For the full list of galaxies in the 90% volume go to the NED Gravitational Wave Followup service at https://ned.ipac.caltech.edu/uri/NED::GWF/. 

The NED-GWF service provides downloadable galaxy lists and visualizations for candidate host galaxies. For each GW alert, these products are automatically generated and made available within minutes to expedite efficient electromagnetic followup observations. The NED top 20 list is sorted by the joint probability of the 3D localization and the WISE W1 luminosity, but users can sort on additional pre-computed prioritization metrics (star formation rate, P_3D*P_SFR; and specific star formation rate, P_3D*P_sSFR; etc.) which are available via downloading the entire galaxy list inside the event's probability volume.

         Galaxy              RA        Dec     Distance m_NUV  mErr_NUV  m_Ks  mErr_Ks  m_W1  mErr_W1   P_3D   P_3D_LumW1
                            (Deg)     (Deg)       (Mpc)  (AB)     (mag) (Vega)   (mag) (Vega)   (mag)  (Prob)     (Prob)
------------------------- ---------- ---------- ------- ----- --------- ----- -------- ----- -------- -------- ----------
WISEA J061043.04-023625.2  92.679167  -2.606972  330.48    --        -- 13.61     0.18  9.21     0.01 8.92e-01   2.03e-03
WISEA J055357.30-060207.5  88.488792  -6.036111  224.38    --        -- 13.16     0.22  8.50     0.01 8.37e-01   1.79e-03
WISEA J071238.60-372350.1 108.161375 -37.397306  390.44    --        -- 13.39     0.19  9.73     0.01 7.31e-01   1.46e-03
WISEA J073438.51-432253.0 113.660542 -43.381306  383.92    --        -- 13.68     0.22  9.90     0.01 8.82e-01   1.43e-03
WISEA J072905.20-623320.6 112.271625 -62.555722  393.80    --        -- 13.64     0.16  9.97     0.00 8.92e-01   1.40e-03
WISEA J083134.97-803600.3 127.896000 -80.600111  379.45    --        -- 12.90     0.13  9.85     0.01 8.41e-01   1.34e-03
WISEA J201533.66-842204.1 303.890667 -84.367722  311.23    --        -- 12.78     0.15  9.22     0.00 6.58e-01   1.28e-03
WISEA J072738.54-425615.1 111.910625 -42.937667  413.61    --        -- 13.24     0.15 10.12     0.01 8.49e-01   1.28e-03
WISEA J051736.04+131107.5  79.400292  13.185306  257.07    --        -- 12.35     0.10  8.88     0.01 6.50e-01   1.27e-03
WISEA J070806.23-280528.7 107.025875 -28.091250  363.10    --        -- 12.97     0.12  9.83     0.01 8.36e-01   1.26e-03
WISEA J071641.54-440551.7 109.173125 -44.097722  405.31    --        -- 13.57     0.19 10.10     0.01 8.38e-01   1.22e-03
WISEA J071514.23-444325.0 108.809292 -44.723639  310.49    --        -- 13.22     0.21  9.57     0.01 8.01e-01   1.11e-03
WISEA J070342.88-284717.5 105.928583 -28.788250  393.85    --        -- 13.08     0.12 10.03     0.01 7.57e-01   1.11e-03
WISEA J071442.74-325953.2 108.678125 -32.998472  332.08    --        -- 13.13     0.22  9.73     0.01 7.63e-01   1.05e-03
WISEA J072927.23-514825.9 112.363833 -51.807111  371.85    --        -- 13.15     0.12 10.17     0.01 8.31e-01   9.62e-04
WISEA J063501.19-220426.1  98.754542 -22.073778  339.10    --        -- 13.60     0.21  9.97     0.01 7.93e-01   9.05e-04
WISEA J074213.61-513130.2 115.556667 -51.524778  307.38    --        -- 12.67     0.06  9.86     0.01 8.44e-01   9.04e-04
WISEA J073702.29-543332.7 114.259500 -54.559083  324.86    --        -- 12.06     0.13  9.82     0.00 7.43e-01   9.00e-04
WISEA J071346.05-430854.4 108.441833 -43.148472  394.97    --        -- 13.68     0.21 10.54     0.01 8.70e-01   7.98e-04
WISEA J070806.38-405759.9 107.027042 -40.967000  284.57    --        -- 13.79     0.14  9.81     0.01 8.35e-01   7.82e-04

Table: Top 20 galaxies in NED-LVS that fall in the 90% probability volume for S230518h sorted by the joint probability of 3D position and WISE W1 luminosity (P_3D*P_LumW1). Galaxy is the NED preferred name. RA and Dec are the Equatorial coordinates in degrees (J2000). Distance is the distance to the galaxy in Mpc. m_NUV and mErr_NUV are the apparent magnitude and error from GALEX. m_Ks and mErr_Ks are the apparent magnitude and error from 2MASS. m_W1 and mErr_W1 are the apparent magnitude and error from AllWISE. P_3D is the probability that the galaxy is in the volume given the distance of GW event. P_3D_LumW1 is the joint probability within the volume weighted by the WISE1 luminosity of the galaxy (P_3D * P_LumW1).