[vsnet-grb-info 14013] Fermi403206457: continued P60 observations and fading behavior

[GCN Circulars]

TITLE:   GCN CIRCULAR
NUMBER:  15327
SUBJECT: Fermi403206457: continued P60 observations and fading behavior
DATE:    13/10/13 07:26:44 GMT
FROM:    Daniel Perley at Caltech  <dperley at astro.caltech.edu>

D. A. Perley (Caltech), S. B. Cenko (GSFC), and M. M. Kasliwal (Carnegie
Observatories/Princeton) report:

We imaged PTF13dsw, the possible optical counterpart to Fermi trigger
403206457 (Kasliwal et al., GCN 15324) with the Palomar 60-inch
telescope starting at 05:16:19 UT in i, r, and g filters.  Five
exposures of 180 seconds each were acquired per filter.

Calibrating to USNO B1.0 stars in the field, photometry of the candidate 
gives an approximate magnitude of R = 21.2 (+/- 0.2) in a stack of 15 
minutes of r-band imaging at midpoint UT 05:40.  As also noted by 
Malesani et al. (GCN 15325) the continued, significant fading relative 
to the previous night is consistent with that of a GRB afterglow and 
strengthens the association of this source with the Fermi trigger.