TITLE: GCN CIRCULAR NUMBER: 25549 SUBJECT: LIGO/Virgo S190426c: Update on Probability of Terrestrial Origin DATE: 19/08/29 14:46:43 GMT FROM: Deep Chatterjee at University of Wisconsin, Milwaukee The LIGO Scientific Collaboration and Virgo Collaboration report: A revised computation of the classification of the candidate based on detection-pipeline-specific foreground and background models is available. The probability of the source being of terrestrial origin is now estimated to be 58% in contrast to the original estimation of 14% inĀ  GCN Circular 24237. This revision was necessitated by a bug-fix in the source-classification code. This same bug-fix was used to update the event candidate S190510g, as reported in GCN Circular 24462. We apologize for the delay in updating the information for this event. The estimated false alarm rate is unchanged at 1.9e-08 Hz, or about one per 1.6 years. Note that future offline analyses may infer a different terrestrial probability and/or false alarm rate. The new p_astro.json file in GraceDB at https://gracedb.ligo.org/superevents/S190426c/ reports that the revised classification of the candidate is Terrestrial (58%), BNS (24%), MassGap (12%), NSBH (6%) and BBH (<1%). Note that the parameter estimation based classification reported in GCN Circular 24411 is unchanged: Assuming that the candidate S190426c is astrophysical in origin, the relative probabilities amongst the signal categories NSBH : MassGap : BNS : BBH are approximately 12 : 5 : 3 : 0 based on posterior support.