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 $\sim2$ 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 ($\Delta m_{15}(B) = 0.80 \pm 0.05$), a
$B$-band maximum at $2457015.82 \pm 0.03$, a rise time of $16.94^{+ 0.11 }_{-
0.10 }$ days, and moderate host--galaxy extinction ($E(B-V)_{\textrm{host}} =
0.33 \pm 0.06$). Using ASASSN-14lp we derive a distance modulus for NGC 4666 of
$\mu = 30.8 \pm 0.2$ corresponding to a distance of $14.7 \pm 1.5$ Mpc.
However, adding ASASSN-14lp to the calibrating sample of Type Ia supernovae
still requires an independent distance to the host galaxy. Finally, using our
early-time photometric and spectroscopic observations, we rule out red giant
secondaries and, assuming a favorable viewing angle and explosion time, any
non-degenerate companion larger than $0.34 R_{\textrm{sun}}$.
