[vsnet-grb-info 15066] Fermi423717114: iPTF optical transient candidates

[GCN Circulars]

TITLE:   GCN CIRCULAR
NUMBER:  16360
SUBJECT: Fermi423717114: iPTF optical transient candidates
DATE:    14/06/07 03:08:08 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:

Fermi GBM reported trigger 423717114 at 2014-06-06 03:11:51.86 UT. We
have searched for optical counterparts using the Palomar 48-inch
Oschin telescope (P48). Based on the final Fermi GBM localization, we
observed 10 fields covering 73 deg2, with an estimated 56% chance of
containing the true location of the event.

Sifting through candidate variable sources using image subtraction
and standard iPTF vetting procedures, we detected several optical
transients.

iPTF14bfu has no previous detections in iPTF from 2013-05-23 through
2013-10-13, and no obvious host associations. From 4.3 to 5.5 hours
after the burst, it faded from r = 19.89 +/- 0.10 to 20.32 +/- 0.14
mag, fitting a power law of alpha = -1.6 +/- 0.7 relative to the time
of the GBM trigger. It is at the coordinates:
 RA(J2000)  =  21h 52m 29.97s (328.124877 deg)
 Dec(J2000) = +32d 00' 50.6"  (+32.014053 deg)

iPTF14bfw is coincident with the faint galaxy SDSS
J220322.02+291451.1. It was at r = 19.96 +/- 0.06 and possibly
fading, at the coordinates:
 RA(J2000)  =  22h 03m 22.04s (330.841830 deg)
 Dec(J2000) = +29d 14' 51.8"  (+29.247730 deg)

iPTF14bgc, was at r = 18.44 +/- 0.02 and possibly fading. It is
coincident with a r = 21.07 +/- 0.08 mag point source in our coadded
reference image composed of exposures from 2013-07-31 through
2013-09-24. It is at the coordinates:
 RA(J2000)  =  21h 45m 36.14s (326.400599 deg)
 Dec(J2000) = +32d 08' 57.9"  (+32.149426 deg)

iPTF14bga, was at r = 19.75 +/- 0.06 mag and possibly fading. It is
coincident with a r = 20.42 +/- 0.17 mag point source in our
reference image composed of exposures from 2011-07-29 through
2011-10-20. It is a the coordinates:
 RA(J2000)  =  22h 12m 43.78s (333.182423 deg)
 Dec(J2000) = +33d 39' 43.7"  (+33.662146 deg)

Further observations are planned, and are encouraged to determine
the nature of these candidates and determine if any of them are
indeed associated with the Fermi trigger.

The diagram
http://www.its.caltech.edu/~lsinger/iptf/Fermi423717114.pdf shows the
locations of our candidates and the ten P48 fields in relation to the
Fermi GBM 1- and 2-sigma statistical+systematic contours.

We thank the Fermi-GBM team for sharing their detailed localizations
with us.