* Astronomy

Title: The Young and Bright Type Ia Supernova ASASSN-14lp: Discovery, Early-Time Observations, First-Light Time, Distance to NGC 4666, and Progenitor Constraints
Author: B. J. Shappee, A. L. Piro, T. W.-S. Holoien, J. L. Prieto, C. Contreras, K. Itagaki, C. R. Burns, C. S. Kochanek, K. Z. Stanek, E. Alper, U. Basu, J. F. Beacom, D. Bersier, J. Brimacombe, E. Conseil, A. B. Danilet, Subo Dong, E. Falco, D. Grupe, E. Y. Hsiao, S. Kiyota, N. Morrell, J. Nicolas, M. M. Phillips, G. Pojmanski, G. Simonian, M. Stritzinger, D. M. Szczygiel, T. A. Thompson, J. Thorstensen, M. Wagner, P. R. Woniak

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 (Delta m15(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 0.34 solar radii for favourable viewing angles and estimates of the explosion time.

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