GRB 000301C (2.2x2.2 arcmin)
|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 http://www.astro.bio2.edu/grb/ This message may be cited."
|Columbia University Astronomy and Astrophysics, and MDM Observatory|