The Young and Bright Type Ia Supernova ASASSN-14lp: Discovery, Early-Time Observations, First-Light Time, Distance to NGC 4666, and Progenitor Constraints
On 2014 Dec. 9.61, the All-Sky Automated Survey for SuperNovae (ASAS-SN or "Assassin") discovered ASASSN-14lp just ∼2 days after first light using a global array of 14-cm diameter telescopes. ASASSN-14lp went on to become a bright supernova (V=11.94 mag), second only to SN 2014J for the year. We present prediscovery photometry (with a detection less than a day after first light) and ultraviolet through near-infrared photometric and spectroscopic data covering the rise and fall of ASASSN-14lp for more than 100 days. We find that ASASSN-14lp had a broad light curve (Δm15(B)=0.796±0.001stat), a B-band maximum at 2457015.823±0.030stat, a rise time of 16.94−0.11+0.11 days, and moderate host--galaxy extinction (E(B−V)host=0.329±0.001stat). Using ASASSN-14lp we derive a distance modulus for NGC 4666 of μ=30.834±0.003stat±0.16syst corresponding to a distance of 14.68±0.02stat±1.15syst Mpc. However, a tip of the red giant branch distance to the host galaxy should be measured to allow ASASSN-14lp to be added to the calibrating sample of Type Ia supernovae. Finally, using our early-time photometric and spectroscopic data along with our derived light curve properties, we rule out red giant secondaries with limits on the radius of a non-degenerate companion as small as 0.34R⊙ for favorable viewing angles and estimates of the explosion time