[vsnet-grb-info 15595] GRB 141005A: P60 probable afterglow deteaction

[GCN Circulars]

TITLE:   GCN CIRCULAR
NUMBER:  16884
SUBJECT: GRB 141005A: P60 probable afterglow deteaction
DATE:    14/10/05 06:53:57 GMT
FROM:    Daniel Perley at Caltech  <dperley at astro.caltech.edu>

D. A. Perley (Caltech) reports on behalf of a larger collaboration:

The Palomar 60-inch robotic telescope automatically triggered on the 
Swift-BAT alert for GRB 141005A (GCN 16882, D'Elia et al.) and began 
observations of the field at 05:16:28 UT, 202 seconds after the BAT 
trigger.  A sequence of cycling 60-second r, i, and z band images were 
acquired, ending at 05:33:20 UT.

In the initial images we identify a source inside the SPER XRT error 
circle at the following position:

RA  = 19:24:22.392
dec = +36:05:42.26
(J2000, +/- 0.3")

The source is faint and probably fading, from r = 20.6 +/- 0.2 and i = 
20.0 +/- 0.2 in the initial exposures to r = 21.4 +/- 0.3 and i = 21.3 
+/- 0.4 in the final exposures.   The source is also present in archival 
imaging of the field from SDSS.  Measuring the flux of the source in the 
same aperture in these images yields magnitudes of g=21.9, r=21.6, 
i=21.3, z=20.7.

These observations suggest a faint optical afterglow superimposed on a 
host galaxy or Galactic foreground star.  More observations are 
encouraged to characterize this object.