Observations of the spectrophotometric standard star LTT 3218 (see Hamuy et al., PASP, 104, 533) was done through a 10" slit using grism 4 and 5 with the Thompson CCD, and using grisms 6 and 7 with the Ford-Loral CCD. Count rates in other grisms than those measured can be inferred from the transmission curves of the various grisms.
Table: Count rates in 
for a monochromatic magnitude 
=
12.0