[vsnet-grb-info 1890] GRB 050801, SMARTS optical/IR afterglow observations

[GCN Circulars]

TITLE:   GCN GRB OBSERVATION REPORT
NUMBER:  3729
SUBJECT: GRB 050801, SMARTS optical/IR afterglow observations
DATE:    05/08/02 02:37:50 GMT
FROM:    Bethany Cobb at Yale U  <cobb at astro.yale.edu>

B. E. Cobb and C. D. Bailyn (Yale), part of the larger SMARTS
consortium, report:

Using the ANDICAM instrument on the 1.3m telescope at CTIO, we
obtained optical/IR imaging of the error region of GRB 050801
(GCN 3725, Band et al.) with a mid-exposure time of
2005-08-02 00:01 UT, which is ~5.5 hours post-burst.
Total summed exposure times amounted to 15 minutes in I and V and
12 minutes in J and K.

The afterglow of GRB 050801 (GCN 3723, Rykoff et al.) is
detected in our optical images.  However, the afterglow
is not significantly detected in our IR images.

Preliminary photometry, obtained in comparison with
USNO-B1.0 stars, indicates the magnitude of the
afterglow at ~5.5 hours post-burst to be I = 20.2+/-0.2.

The afterglow is not bright enough in the individual optical
frames to significantly measure its decay over our ~40 minutes
of observations.

In comparison with 2MASS stars, the limiting IR magnitudes
are J > 18.6+/-0.2 and K > 17.0+/-0.2.