Low flux levels have been a major obstacle to overcome in this project. At redshifts of 0.25
0.45, the [O II] 
37263729 Åemission line doublet is observed in the blue between 4659 Åand 5400 Å. Until very recently, CCD detectors have been plagued by poor blue quantum efficiency (15-25
). The LORAL3 CCD at CFHT is no exception with a quantum efficiency of 23 at 4500 Å, but new CCDs with high blue quantum efficiency (80 at 5000 Å) will greatly alleviate this problem in the future.
Due to the very low [O II] flux levels (typical S/N ratio per pixel 
23), it was important to choose a method which used all the pixels simultaneously to statistically find the best parameter values and their respective uncertainties. The synthetic rotation curve fitting method described below can be used to extract internal kinematics from faint, spatially-resolved emission line spectra.