GCN Circular 24442

The LIGO Scientific Collaboration and the Virgo Collaboration report:


We identified the compact binary merger candidate S190510g during

real-time processing of data from LIGO Hanford Observatory (H1), LIGO

Livingston Observatory (L1), and Virgo Observatory (V1) at 2019-05-10

02:59:39.292 UTC (GPS time: 1241492397.292). The candidate was found

by the GstLAL [1] analysis pipeline.


S190510g is an event of interest because its false alarm rate, as

determined by the online analysis, is 8.4e-10 Hz, or about one in 37

years. The event's properties can be found at this URL:


https://gracedb.ligo.org/superevents/S190510g


The classification of the GW signal, in order of descending

probability, is BNS (98%), Terrestrial (2%), NSBH (<1%), BBH (<1%), or

MassGap (<1%).


Assuming the candidate is astrophysical in origin, there is strong

evidence for the lighter compact object having a mass < 3 solar masses

(HasNS: >99%). Using the masses and spins inferred from the signal,

there is strong evidence for matter outside the final compact object

(HasRemnant: >99%).


One skymap is available at this time and can be retrieved from the

GraceDB event page:

* bayestar.fits.gz, an updated localization generated by BAYESTAR

[2], distributed via GCN notice about an hour after the candidate


For the bayestar.fits.gz skymap, the 90% credible region is 3462 deg2.

Marginalized over the whole sky, the a posteriori luminosity distance

estimate is 269 +/- 108 Mpc (a posteriori mean +/- standard

deviation).


For further information about analysis methodology and the contents of

this alert, refer to the LIGO/Virgo Public Alerts User Guide

<https://emfollow.docs.ligo.org/userguide/>.


[1] Messick et al. PRD 95, 042001 (2017)

[2] Singer & Price PRD 93, 024013 (2016)