AAVSO: American Association of Variable Star Observers

BVRI Photometry of SN 2016coj in NGC 4125

Volume 45 number 1 (2017)

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Michael Richmond
School of Physics and Astronomy, Rochester Institute of Technology, Rochester, NY 14623, mwrsps@rit.edu
Brad Vietje
Northeast Kingdom Astronomy Foundation, PO Box 173, Peacham, VT 05862, brad@nkaf.org


We present BVRI photometry of supernova (SN) 2016coj in NGC 4125 from 9 days before to 57 days after its B-band maximum light. Our light curves and color curves suggest that this event belongs to the “normal” class of type Ia SNe, with a decline rate parameter Delta m15(B) = 1.32 ± 0.10, and that it suffers little extinction. Adopting a distance modulus to its host galaxy of (m – M) = 31.89 mag, we compute extinction-corrected peak absolute magnitudes of MB = –19.01, MV = –19.05, MR = –19.03, and MI = –18.79. The explosion occurred close enough to the nucleus of NGC 4125 to hinder the measurement of its brightness. We describe our methods to reduce the effect of such host-galaxy contamination, but it is clear that our latest values suffer from systematic bias.