We present optical and infrared photometry of the unusual Type Ia supernova 2000cx .
With the data of Li et al .
( 2001 ) and Jha ( 2002 ) , this comprises the largest dataset ever assembled for a Type Ia SN , more than 600 points in UBVRIJHK .
We confirm the finding of Li et al .
regarding the unusually blue B - V colors as SN 2000cx entered the nebular phase .
Its I -band secondary hump was extremely weak given its B -band decline rate .
The V minus near infrared colors likewise do not match loci based on other slowly declining Type Ia SNe , though V - K is the least “ abnormal ” .
In several ways SN 2000cx resembles other slow decliners , given its B -band decline rate ( \Delta m _ { 15 } ( B ) = 0.93 ) , the appearance of Fe III lines and weakness of Si II in its pre-maximum spectrum , the V - K colors and post-maximum V - H colors .
If the distance modulus derived from Surface Brightness Fluctuations of the host galaxy is correct , we find that the rate of light increase prior to maximum , the characteristics of the bolometric light curve , and the implied absolute magnitude at maximum are all consistent with a sub-luminous object with \Delta m _ { 15 } ( B ) \approx 1.6-1.7 having a higher than normal kinetic energy .