Columbia University Astronomy and 

MDM Observatory GRB Team

GRB 000301C (2.2x2.2 arcmin)

1.3m CCD

GCN Circular #585: GRB 000301C, Optical Color
J. P. Halpern, N. Mirabal, & S. Lawrence (Columbia U.) report
on behalf of the MDM Observatory GRB follow-up team:

"We also obtained B-band images of GRB 000301C on March 4.52 UT
using the MDM 1.3m telescope.  By employing the Henden et al.
(GCN #583) photometry of the comparison stars A and D of 
Garnavich et al. (GCN #573), we measure B = 21.41 +/- 0.04,
and we determine that B-R = 0.77 +/- 0.06 at this time.
Correcting for the Schlegel et al. (1998) Galactic extinction at 
this location, A_B = 0.23 and A_R = 0.14, we find an intrinsic
B-R = 0.68 +/- 0.06, which corresponds to a spectral slope
beta = -0.87 +/- 0.14.  This value, together with the temporal
decay slope alpha = -1.07 +/- 0.09 (GCN #581,582), is consistent
within the errors with the canonical alpha = (3/2)beta behavior
of a spherical afterglow in an uniformly dense medium.
Little intrinsic extinction is required to explain the color.

The B-band image is posted at

This message may be cited."

Jules Halpern
Nestor Mirabal
Steve Lawrence
Columbia University Astronomy and Astrophysics, and MDM Observatory

MDM Observatory