[vsnet-grb-info 5977] GRB 080319B: Continued Gemini-N monitoring

[GCN Circulars]

TITLE:   GCN CIRCULAR
NUMBER:  7621
SUBJECT: GRB 080319B: Continued Gemini-N monitoring
DATE:    08/04/15 22:36:51 GMT
FROM:    Nial Tanvir at IofA U.Cambridge  <nrt at ast.cam.ac.uk>

N. R. Tanvir (U. Leicester), D. A. Perley (UC Berkeley),
A. J. Levan (U. Warwick), J. S. Bloom (UC Berkeley),
A. S. Fruchter (STScI) and E. Rol (U. Leicester) report:

We obtained a further epoch of observations of GRB 080319B with
Gemini-North/GMOS on April 14 UT. These observations yielded the
following magnitudes: g=25.80+/-0.09, r=24.93+/-0.07, i=24.22+/-0.05.

Although the r-band magnitude is consistent with a continued power-law
decline in flux, the source is now clearly much redder than it was at
early times, suggesting it is likely contaminated by light from a host
galaxy and/or associated supernova.  The g-band observation, which
would be less contaminated by any SN light, indicates a steeper
decline which may be consistent with a break in the underlying
afterglow light curve (GCN 7567).

The absence of any extended emission in the previous HST observations
(GCN 7569) argues against a significant host contribution, although a very
compact host is not ruled out.

Further analysis is ongoing.

We thank Gemini staff astronomers, particularly Sandy Leggett, for
their support in obtaining these observations.