Optical and Infrared Photometry of the Type I[CLC]a[/CLC] Supernovae 1999[CLC]da[/CLC], 1999[CLC]dk[/CLC], 1999[CLC]gp[/CLC], 2000[CLC]bk[/CLC], and 2000[CLC]ce[/CLC]

We present BVRI photometry of the Type Ia supernovae 1999da, 1999dk, 1999gp,2000bk, and 2000ce, plus infrared photometry of three of these. These objectsexhibit the full range of decline rates of Type Ia supernovae. Combined opticaland infrared data show that families of V - infrared color curves can be usedto derive the host extinction (A_V) of these objects. Existing data do not yetallow us to construct these loci for all color indices and supernova declinerates, but the V-K color evolution is sufficiently uniform that it allows thedetermination of host extinction over a wide range of supernova decline ratesto an accuracy of roughly +/- 0.1 mag. We introduce a new empirical parameter,the mean I-band flux 20 to 40 days after maximum light, and show how it isdirectly related to the decline rate.Comment: 53 pages, 18 figures, accepted for publication in the Astronomical Journal (scheduled for the September 2001 issue