We carefully analyze the WFPC2 and STIS images of GRB970228. We measure
magnitudes for the GRB970228 point source component in the WFPC2 images of
V=26.20β0.13+0.14β, Icβ=23.94β0.09+0.10β and
V=26.52β0.18+0.16β, Icβ=24.31β0.11+0.15β on March 26 and April 7,
respectively; and Rcβ=27.09β0.14+0.14β on September 4 in the STIS image.
For the extended component, we measure magnitudes of
Rcβ=25.48β0.20+0.22β in the combined WFPC2 images and
Rcβ=25.54β0.22+0.33β in the STIS image, which are consistent with no
variation. This value is fainter than previously reported (Galama et al. 98)
and modifies the previously assumed magnitudes for the optical transient when
it faded to a level where the extended source component contribution was not
negligible, alleviating the discrepancy to a power-law temporal behavior. We
also measure a color of V606ββI814β=β0.18β0.61+0.51β for the
extended source component. Taking into account the extinction measured in this
field (Castander & Lamb 1998), this color implies that the extended source is
most likely a galaxy with ongoing star formation.Comment: 21 pages, including 8 figures. Submitted to Ap