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 = 26.20 ^ { +0.14 } _ { -0.13 } , I _ { c } = 23.94 ^ { +0.10 } _ { -0.09 } and V = 26.52 ^ { +0.16 } _ { -0.18 } , I _ { c } = 24.31 ^ { +0.15 } _ { -0.11 } on March 26 and April 7 , respectively ; and R _ { c } = 27.09 ^ { +0.14 } _ { -0.14 } on September 4 in the STIS image .
For the extended component , we measure magnitudes of R _ { c } = 25.48 ^ { +0.22 } _ { -0.20 } in the combined WFPC2 images and R _ { c } = 25.54 ^ { +0.33 } _ { -0.22 } in the STIS image , which are consistent with no variation .
This value is fainter than previously reported ( [ Galama et al .
1998 ] ) 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 V _ { 606 } - I _ { 814 } = -0.18 ^ { +0.51 } _ { -0.61 } 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 .