[vsnet-grb-info 15068] Fermi 423717114: Additional P48 and P60 observations

[GCN Circulars]

TITLE:   GCN CIRCULAR
NUMBER:  16362
SUBJECT: Fermi 423717114: Additional P48 and P60 observations
DATE:    14/06/07 12:01:45 GMT
FROM:    Daniel Perley at Caltech  <dperley at astro.caltech.edu>

D. A. Perley and L. Singer (Caltech) report on behalf of a larger 
collaboration:

We re-imaged the same ten P48 fields near the center of the error circle 
of Fermi trigger 423717114 (Singer et al., GCN 16360) between 09:28:30 
through 09:42:30 UT on the night of 2014-06-07.  iPTF14bfw and iPTF14bga 
have not faded relative to our observations during the previous night.

For iPTF14bgc, we measure R = 20.68 +/- 0.21, consistent with the 
point-like counterpart in our reference images but significantly fainter 
than the previous night. A power law fit to the decay gives a temporal 
index of alpha = -1.1 +/- 0.1.

We do not detect iPTF14bfu in our P48 image with a limiting magnitude of 
R ~ 21.1.  Further imaging was obtained with the Palomar 60-inch 
telescope on two epochs, starting at 07:47:45 and 10:47:31, 
respectively.  We acquired a series of seven 180-second images in r-band 
and five 180-second images in i-band in the first epoch, and a series of 
seven 180-second images in r-band during the second epoch.

We detect the transient in a combined stack of all exposures in each 
band/epoch.  Calibrating relative to USNO-B1.0 stars in the image, we 
measure magnitudes of:

r = 21.1 +/- 0.2 (t_mid = 28.78 hr)
i = 21.0 +/- 0.3 (t_mid = 29.12 hr)
r = 21.4 +/- 0.2 (t_mid = 31.78 hr)

Relative to the magnitudes presented by Singer et al., these 
observations suggest an average temporal index of only alpha~-0.5, much 
slower than observed during the first night. Further observations are 
ongoing.