TITLE: GCN CIRCULAR NUMBER: 25202 SUBJECT: LIGO/Virgo S190728q: Identification of a Faint Blue Static Source at the Location of ZTF19abjethn DATE: 19/07/28 17:39:13 GMT FROM: Daniel Goldstein at Caltech Danny Goldstein (Caltech), Erik Kool (OKC), Jeff Newman (U. Pittsburgh), Rongpu Zhou (U. Pittsburgh), Mansi M. Kasliwal (Caltech), Igor Andreoni (Caltech), Daniel A. Perley (LJMU), Michael W. Coughlin (Caltech) On behalf of the Zwicky Transient Facility (ZTF) and Global Relay of Observatories Watching Transients Happen (GROWTH) collaborations ZTF19abjethn (GROWTH Collaboration 2019; GCN 25199), an optical counterpart candidate to the gravitational wave trigger S190728q (The LIGO Scientific Collaboration and the Virgo Collaboration 2019; GCN 25187), is spatially coincident (to within less than one arcsecond) with a faint blue static source. The source is detected only marginally in DECam Legacy Survey (DECaLS) and SDSS imaging thus we are unable to estimate a photometric redshift or stellar mass for the potential host, assuming the source is a galaxy; we are also unable to determine if the source is a star or a galaxy. The source has the following magnitudes in DECaLS DR7: ----------------------------------------------------------------------------------------------- Name | RA (deg) | DEC (deg) | Filter | Mag | Magerr | Filter| Mag | Magerr | Filter | Mag | Magerr | Filter --------------+-------------+-------------+--------+-------+---------+-------+-------+--------- SDSS J214534.91+204126.2 | 326.395467148 | 23.456085 | 0.07854421 | g | 23.09552 | 0.07489753 | r | 23.554304 | 0.36628282 | z ----------------------------------------------------------------------------------------------- Spectroscopic follow-up is encouraged. ZTF and GROWTH are worldwide collaborations comprising Caltech, USA; IPAC, USA, WIS, Israel; OKC, Sweden; JSI/UMd, USA; U Washington, USA; DESY, Germany; MOST, Taiwan; UW Milwaukee, USA; LANL USA; Tokyo Tech, Japan; IIT-B, India; IIA, India; LJMU, UK; TTU, USA; and USyd, Australia. ZTF acknowledges the generous support of the NSF under AST MSIP Grant No 1440341. GROWTH acknowledges generous support of the NSF under PIRE Grant No 1545949. This message may be cited.