Skip to main content
Testing. You are viewing the public testing version of GCN. For the production version, go to
New Announcement Feature, Code of Conduct, Circular Revisions. See news and announcements

GCN Circular 16362

Fermi 423717114: Additional P48 and P60 observations
2014-06-07T12:01:45Z (10 years ago)
Daniel Perley at Caltech <>
D. A. Perley and L. Singer (Caltech) report on behalf of a larger 

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 
Looking for U.S. government information and services? Visit