GCN Circular 14615

D. A. Perley and S. Tang (Caltech) report:

On the night of 2013-05-09 UT we observed the location of GRB 130427A 
with the Low Resolution Imaging Spectrometer (LRIS) on the Keck I 10m 
telescope, during excellent weather conditions (clear skies and 0.7 
arcsecond seeing).

In a pair of 90 second g-band images we clearly detect the transient 
superimposed on a faint, extended source that we identify as the host 
galaxy.  While blended with the light of the transient, the diameter of 
this extended emission is approximately 3 arcseconds, corresponding to a 
physical size of ~14 kpc at a redshift of z=0.34.  The magnitude of the 
transient at this time (within a 1" aperture centered on the optical 
position) is:

  g = 21.23 +/- 0.04 mag  (t = 12.00 days)

This is consistent (within uncertainties) with the rate of decay seen in 
recent P60 observations between 1-8 days post-GRB after subtraction of 
the host galaxy.

We also acquired a deep sequence of spectroscopic observations (2000 sec 
total integration) with LRIS, covering a wavelength range from 
approximately 3250 to 10300 Angstroms.   We observe no broad features or 
other evidence of contribution of a supernova to the spectrum at this 
time, similar to as reported from LBT observations two nights previously 
(Garnavich et al., GCN 14605
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 .)

We thank and S. R. Kulkarni and the PTF collaboration for these 
observations.