BVRI Photometry of SN 2011fe in M101
Michael W. Richmond
Horace A. Smith
Received March 19, 2012; revised April 4, 2012; accepted April 11, 2012
We present BVRI photometry of Supernova 2011fe in M101, starting 2.9 days after the explosion and ending 179 days later. The light curves and color evolution show that SN 2011fe belongs to the “normal’’ subset of type Ia supernovae, with a decline parameter Dm15(B) = 1.21 ± 0.03 mag. After correcting for the small amount of extinction in the line of sight, and adopting a distance modulus of (m – M) = 29.10 mag to M101, we derive absolute magnitudes MB = –19.21, MV = –19.19, MR = –19.18, and MI = –18.94. We compare the voluminous record of visual measurements of this event to our CCD photometry and find evidence for a systematic difference which depends on color.