We present deep HST imaging , as well as ground-based imaging and spectroscopy , of the optical afterglow associated with the long-duration gamma-ray burst GRB 990712 and its host galaxy .
The data were obtained 48–123 days after the burst occurred .
The magnitudes of the host ( R = 21.9 , V = 22.5 ) and optical afterglow ( R = 25.4 , V = 25.8 , 47.7 days after the burst ) favor a scenario where the optical light follows a pure power-law decay with an index of \alpha \sim - 1.0 .
We find no evidence for a contribution from a supernova like SN1998bw .
This suggests that either there are multiple classes of long-duration gamma-ray bursts , or that the peak luminosity of the supernova was > 1.5 mag fainter than SN1998bw .
The HST images and EFOSC2 spectra indicate that the gamma-ray burst was located in a bright , extended feature ( possibly a star-forming region ) 1.4 kpc from the nucleus of a 0.2 L ^ { \ast } _ { B } galaxy at z = 0.434 , possibly a Seyfert 2 galaxy .
The late-time afterglow and host galaxy of GRB 990712 bear some resemblance to those of GRB 970508 .