TITLE: GCN CIRCULAR NUMBER: 21505 SUBJECT: LIGO/Virgo G298048: Fermi GBM trigger 524666471/170817529: LIGO/Virgo Identification of a possible gravitational-wave counterpart DATE: 17/08/17 13:21:42 GMT FROM: Reed Clasey Essick at MIT The LIGO Scientific Collaboration and the Virgo Collaboration report: The online CBC pipeline (gstlal) has made a preliminary identification of a GW candidate associated with the time of Fermi GBM trigger 524666471/170817529 at gps time 1187008884.47 (Thu Aug 17 12:41:06 GMT 2017) with RA=186.62deg Dec=-48.84deg and an error radius of 17.45deg. The candidate is consistent with a neutron star binary coalescence with False Alarm Rate of ~1/10,000 years. An offline analysis is ongoing. Any significant updates will be provided by a new Circular. [GCN OPS NOTE(17aug17): Per author's request, the LIGO/VIRGO ID was added to the beginning of the Subject-line.]