GCN Circular 11735

S. B. Cenko, J. S. Bloom, and A. A. Miller (UC Berkeley) report on behalf
of a larger collaboration:

The location of the X-ray (Nakahira et al., GCN 11725
Not found
 
 
) and optical (Cenko
et al., GCN 11732
Not found
 
 
) afterglow of GRB 110213B (Negoro et al, GCN 11716
Not found
 
 
) was
observed repeatedly over the seven year period beginning in 1998 as part
of the SDSS Stripe 82 Survey (Bramich et al., MNRAS 2008, 386, 887).  We
have extracted all images covering this location from the SDSS Stripe 82
database to create stacked frames in the g, r, and i filters.  A
false-color composite image of the afterglow location can be found at:

   http://astro.berkeley.edu/~cenko/public/grb/GRB110213B/sdss.png

Using 10 nearby point sources from SDSS for astrometry, we measure a
revised position for the P60 optical afterglow candidate of (J2000.0):

  RA: 02:47:01.45  Dec: +01:08:46.5

The measured uncertainty in the P60-SDSS astrometric tie is 100 mas in
each coordinate.

Offset by 0.9" from the location of the afterglow, we find an extended
source in the pre-outburst SDSS Stripe 82 imaging in all three filters.
We measure coordinates (J2000.0) for this source:

   RA: 02:47:01.41  Dec: +01:08:47.2

Using several nearby point sources from SDSS for comparison, we measure
magnitudes of g' = 23.7, r' = 22.8, i' = 22.3  Additional emission is
marginally detected in the i' filter approximately 3" south of this
position, but its relation to this object is unclear.

This extended source could be a relatively nearby host galaxy for
GRB110213B, although the red colors are somewhat unusual for GRB hosts.