GCN Circular 18029

Subject

GRB 150716A: P60 Candidate Optical Afterglow

Event

Date

2015-07-16T21:02:36Z (11 years ago)

From

S. Bradley Cenko at NASA/GSFC <brad.cenko@nasa.gov>

S. B. Cenko (NASA/GSFC) and D. A. Perley (DARK) report on behalf of a larger collaboration:

We have imaged the location of the X-ray afterglow of GRB 150716A (Kocevski et al., GCN 18027Loading...
 
 ) with the automated Palomar 60 inch telescope.  Observations were obtained in the r, i, and z filters beginning at 07:11 UT (~ 4 minutes after the Swift trigger time) and ending at 8:18 UT.  Within the XRT error circle, we detect a large number of sources, one of which shows marginal evidence for fading:

  RA: 18:33:57.13
  Dec: -12:58:46.3

By comparison with the nearby USNO-B1 catalog star 0770-0591035 (I2 magnitude = 17.66), we measure the following magnitudes for this source:

UT          Magnitude
----------------------------------
07:11      21.48 +/- 0.22
08:17      > 22.15 

The source reported by RATIR (Watson et al, GCN 18028Loading...
 
 ) is clearly detected in our images, but a) does not appear to fade, and b) is outside the revised XRT error circle.

We thank Alan Watson and Nat Butler for sharing the RATIR images with us.