Clearly the spatial resolution of HST has opened up a new dimension to the study of galaxy evolution at high redshift. Hitherto, HST morphological data on large numbers of distant galaxies has generally been confined to samples of galaxies without redshift information, using the Medium Deep Survey (Glazebrook et al., 1995) or comparable material (Driver et al., 1995) or the HDF itself (Abraham et al. 1996). A general conclusion from these has been that the number counts N(m) of galaxies classified morphologically as ellipticals and spirals are roughly as predicted for models with a magnitude or less of luminosity evolution, whereas those of irregular/peculiar galaxies are much steeper, suggesting that it is galaxies with these late-type morphologies that are responsible for the evolution seen in the redshift surveys.
3.1. HST observations of galaxies from the CFRS and LDSS redshift surveys
A new collaborative project between the CFRS and LDSS redshift survey teams has brought these two approaches together, combining the exceptional morphological information from HST with the extensive redshift data from the ground-based CFRS and LDSS redshift surveys. We have obtained HST WFPC2 images of 25 fields from the CFRS and LDSS surveys which have yielded high quality images in F814W for a total of 341 objects (251 CFRS and 90 LDSS) that had previously been observed spectroscopically. These 341 objects have been morphologically classified, both by eye and by machine-based algorithms, and the 2-dimensional light distributions have been fit by multi-parameter bulge+disk models (as in Schade et al. 1995). Several new results have emerged from these analyses.