GCN Circular 17312

Subject

GRB 150120A: P60 optical observations

Event

Date

2015-01-20T04:06:55Z (11 years ago)

From

Daniel Perley at Caltech <dperley@astro.caltech.edu>

D. A. Perley (Caltech) and S. B. Cenko (NASA/GSFC) report:

The Palomar 60-inch robotic telescope began automatic follow-up of the 
location of possibly-short GRB 150120A (D'Elia et al. GCN 17310Loading...
 
 ) 
starting at 2015-01-20 03:00:33 UT, approximately 2.7 minutes after the 
GRB trigger.  A sequence of rotating r, i, and z 60-second exposures was 
acquired, followed by five 180-second exposures in each of r and i 
bands, under good conditions.

No sources are clearly detected inside the enhanced XRT error circle 
(Evans et al., GCN 17311Loading...
 
 ), either in either individual exposures or in 
stacks of all 60-second exposures taken in each filter (approximate UT 
center time 15 minutes post-trigger, limiting magnitudes r>22.5, i>22.4, 
z>20.9).  We detect two faint sources slightly outside the error circle 
in the stacked frames:

  Source A:  RA=00:41:16.55, dec=+33:59:42.87
  Source B:  RA=00:41:16.76, dec=+33:59:42.11

Both sources appear to be marginally detected in SDSS pre-imaging and we 
do not yet have evidence of fading behavior.  Further observations and 
analysis are ongoing.

[GCN OPS NOTE(20jan15):  Per author's request, the date in the third line
was changed from 2015-01-t0 to 2015-01-20.]