  Simultaneous spectroscopic and photometric observations of the Z Cam type
dwarf nova SY Cancri were used to obtain absolute flux calibrations. A
comparison of the photometric calibration with a wide slit spectrophotometric
calibration showed that either method is equally satisfactory. A radial
velocity study of the secondary star, made using the far red NaI doublet,
yielded a mass ratio q = 0.68; this is very different from the value of 1.13
quoted in the literature. Using the new lower mass ratio, and constraining the
mass of the white dwarf to be within reasonable limits, then leads to a mass
for the secondary star that is substantially less than would be expected for
its orbital period if it satisfied a main-sequence mass-radius relationship. We
find a spectral type of M0 that is consistent with that expected for a
main-sequence star of the low mass we have found. However, in order to fill its
Roche lobe, the secondary must be significantly larger than a main sequence
star of that mass and spectral type. The secondary is definitely not a normal
main-sequence star.
