TITLE:   GCN CIRCULAR
NUMBER:  15809
SUBJECT: GRB 140209A: P60 optical afterglow detection
DATE:    14/02/09 09:29:44 GMT
FROM:    Daniel Perley at Caltech  <dperley@astro.caltech.edu>

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

The Palomar 60-inch telescope responded automatically to the Swift alert 
for GRB 140209A (Cenko et al., GCN 15808) and began a sequence of 
60-second exposures in r, i, and z filters at 07:35:30 UT, 4.55 minutes 
after the BAT trigger.  In the reduced images, we clearly detect a 
fading, uncatalogued optical counterpart inside the BAT error circle at 
the following location:

RA  =  05:25:19.034
Dec = +32:29:53.18
(+/- 0.6 arcsec)

Calibrated relative to USNO-B1.0, the source fades steadily from R=17.6 
in the first r-band image to R=19.4 at 41.1 minutes post-GRB, which 
identifies it as the likely optical afterglow of this event.