TITLE:   GCN CIRCULAR
NUMBER:  24375
SUBJECT: LIGO/Virgo S190421ar: Updated localization and classification from LIGO and Virgo data
DATE:    19/05/03 16:14:06 GMT
FROM:    Erik Katsavounidis at MIT  <kats@ligo.mit.edu>

The LIGO Scientific Collaboration and the Virgo Collaboration report:


We have re-analyzed LIGO and Virgo data around the time of the

compact binary coalescence (CBC) candidate S190421ar

(GCN 24141). Parameter estimation has been performed using

LALInference [1] and a new sky map, LALInference.fits.gz,

distributed via GCN Notice about 11 days after the candidate,

is available for retrieval from the GraceDB event page:


https://gracedb.ligo.org/superevents/S190421ar


The updated classification of the GW signal, in order of descending

probability, is BBH (97%), Terrestrial (3%), BNS (<1%), NSBH (<1%),

or MassGap (<1%).


For the LALInference.fits.gz skymap, the 90% credible region is

1444 deg2. Marginalized over the whole sky, the a posteriori

luminosity distance estimate is 1628 +/- 535 Mpc (a posteriori

mean +/- standard deviation). This is the preferred sky map at

this time.


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] Veitch et al. PRD 91, 042003 (2015)