The Type~Ia supernova (SN~Ia) 2017cfd in IC~0511 (redshift z = 0.01209+- 0.00016$) was discovered by the Lick Observatory Supernova Search 1.6+-0.7 d after the fitted first-light time (FFLT; 15.2 d before B-band maximum brightness). Photometric and spectroscopic follow-up observations show that SN~2017cfd is a typical, normal SN~Ia with a peak luminosity MB ~ -19.2+-0.2 mag, Delta m15(B) = 1.16 mag, and reached a B-band maximum ~16.8 d after the FFLT. We estimate there to be moderately strong host-galaxy extinction (A_V = 0.39 +- 0.03 mag) based on MLCS2k2 fitting. The spectrum reveals a Si~II lambda 6355 velocity of ~11,200 kms at peak brightness. The analysis shows that SN~2017cfd is a very typical, normal SN Ia in nearly every aspect. SN~2017cfd was discovered very young, with multiband data taken starting 2 d after the FFLT, making it a valuable complement to the currently small sample (fewer than a dozen) of SNe~Ia with color data at such early times. We find that its intrinsic early-time (B - V)0 color evolution belongs to the "blue" population rather than to the distinct "red" population. Using the photometry, we constrain the companion star radius to be < 2.5 R_sun, thus ruling out a red-giant companion.
@article{arxiv.1911.07734,
title = {SN 2017cfd: A Normal Type Ia Supernova Discovered Very Young},
author = {Xuhui Han and WeiKang Zheng and Benjamin E. Stahl and Jamison Burke and Jozsef Vinko and Thomas de Jaeger and Thomas G. Brink and Borbala Cseh and Daichi Hiramatsu and D. Andrew Howell and Bernadett Ignacz and Reka Konyves-Toth and Mate Krezinger and Curtis McCully and Andras Ordasi and Dora Pinter and Krisztian Sarneczky and Robert Szakats and Kevin Tang and Krisztian Vida and Jing Wang and Jianyan Wei and J. Craig Wheeler and Liping Xin and Alexei V. Filippenko},
journal= {arXiv preprint arXiv:1911.07734},
year = {2020}
}