Optical photometry of the Type II-P supernova 2004dj in NGC 2403

We present photometric data of the Type II-P supernova (SN) 2004dj in NGC 2403. The multicolor light curves cover the SN from similar to 60 to 200 days after explosion and are measured with a set of intermediate-band filters that have the advantage of tracing the strength variations of some spectral features. The light curves show a flat evolution in the middle of the plateau phase, then decline exponentially at the late times, with a rate of 0.10 +/- 0.03 mag (10 days)(-1) in most of the filters. In the nebular phase, the spectral energy distribution of SN 2004dj shows a steady increase in the flux near 6600 and 8500 8, which may correspond to the emission lines of H alpha and the Ca II near-IR triplet, respectively. The photometric behavior suggests that SN 2004dj is a normal SN II-P. Compared with the light curves of another typical SN II-P, 1999em, we estimate the explosion date to be 2004 June 10 +/- 21 UT (JD 2,453,167 +/- 21) for SN 2004dj. We also estimate the ejected nickel mass during the explosion to be M(Ni-56) 0.023 +/- 0.005 M-circle dot from two different methods, which is typical for a SN II-P. We derive the explosion energy to be E approximate to 0.75(-0.38)(+0.56) 1051 ergs, the ejecta mass to be M approximate to 10.0(-5.2)(+7.4) M-circle dot, and the initial radius to be R approximate to 282(-122)(+253) R-circle dot for the presupernova star of SN 2004dj, which are consistent with other typical SNe II-P.