[vsnet-grb-info 13497] GRB 130609A: P60 nondetection

[GCN Circulars]

TITLE:   GCN CIRCULAR
NUMBER:  14830
SUBJECT: GRB 130609A: P60 nondetection
DATE:    13/06/09 05:28:54 GMT
FROM:    Daniel Perley at Caltech  <dperley at astro.caltech.edu>

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

The Palomar 60-inch telescope automatically responded to GRB 130609A 
(Cummings et al., GCN 14828) and began taking observations at 04:03:23 
UT (58.25 minutes after the BAT trigger) as soon as the sky became dark. 
  A sequence of cycled 60-second r, i, and z images was acquired.  We 
detect no source consistent with the XRT localization in either 
individual images or in combined stacks of the first 6 images in each 
filter.  Approximate 5-sigma limiting magnitudes from the combined 
images at an approximate mean time of 4:20 UT (75 minutes after the GRB 
trigger) are:

r > 22.5
i > 21.5
z > 20.9

These limits are suggestive of a dark GRB.  Cummings et al. report a 
detection of significant excess absorption in the XRT spectrum, which 
may indicate a dust-extinguished (as opposed to high-redshift) event, 
although given the quoted errors there the excess may be only marginal.

NIR follow-up is highly encouraged.