[vsnet-grb-info 14372] Fermi410578384: iPTF optical afterglow candidates for a possible short GRB

[GCN Circulars]

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  <lsinger at caltech.edu>

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
<http://www.its.caltech.edu/~lsinger/iptf/Fermi410578384.pdf>.

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.