TITLE: GCN CIRCULAR NUMBER: 15686 SUBJECT: Fermi410578384: iPTF optical afterglow candidates for a possible short GRB DATE: 14/01/05 16:37:28 GMT FROM: Leo Singer at CIT/PTF L. P. Singer (Caltech), M. M. Kasliwal (Carnegie Observatories/Princeton) and S. B. Cenko (NASA/GSFC) report on behalf of the intermediate Palomar Transient Factory (iPTF) collaboration: At 2014-01-05 01:33:01, Fermi GBM and INTEGRAL SPI-ACS triggered on a possible short event (Fermi trigger 410578384). From 7.4 to 10.5 hours after the burst, we imaged 74 deg^2 with the Palomar 48-inch Oschin telescope (P48), covering some of the intersection between the Fermi 1-sigma statistical+systematic error region and the IPN 3-sigma annulus. Sifting through 60,191 candidate variable sources using standard iPTF vetting procedures, we find the following optical afterglow candidates: iPTF14x, at R=19.7 mag, possibly fading, and near the galaxy SDSS J140427.10+485556.9, at the coordinates: RA(J2000) = 14h 04m 27.27s (211.113610 deg) Dec(J2000) = +48d 55' 55.3" (+48.932017 deg) iPTF14ac, at R=20.1 mag, near the galaxy SDSS J142230.44+482916.8 and in an apparent galaxy cluster at z=0.07, at the coordinates: RA(J2000) = 14h 22m 30.60s (215.627501 deg) Dec(J2000) = +48d 29' 21.5" (+48.489310 deg) iPTF14ae, at R=20.1 mag, possibly fading, near the source SDSS J134527.33+532615.3 (which SDSS classifies as a galaxy), at the coordinates: RA(J2000) = 13h 45m 27.34s (206.363914 deg) Dec(J2000) = +53d 26' 16.9" (+53.438029 deg) iPTF14ai, at R=20.6 mag, coincident with no obvious source in our reference images or in SDSS, at the coordinates: RA(J2000) = 13h 57m 46.05s (209.441870 deg) Dec(J2000) = +45d 16' 09.3" (+45.269258 deg) A diagram of the locations of these candidates, the Fermi-GBM and IPN localizations, and the ten P48 fields that we imaged can be found at . We caution that many contaminating transient or variable sources are found in any such wide-area targeted search, and that it is possible that none of our candidates are associated with the short GRB. Further observations are encouraged to determine the nature of these sources, and whether one of them is related to the Fermi and INTEGRAL trigger. We thank the Fermi and IPN teams for supplying us with the localizations.