SIMBAD references

We present the UBVR_cI_cbroad-band optical photometry of the Type Ic supernova SN 2002ap obtained during 2002 February 6-March 23 in the early decline phases and also later on 2002 August 15. Combining these data with the published ones, the general light-curve development is studied. The time and luminosity of the peak brightness and the peak width are estimated. There is a flattening in the optical light curve about 30 d after the B maximum. The flux decline rates before flattening are 0.127±0.005, 0.082±0.001, 0.074±0.001, 0.062±0.001 and 0.040±0.001 mag/d in U, B, V, R_c and I_cpassbands respectively, while the corresponding values after flattening are about 0.02 mag/d in all the passbands. The maximum brightness of SN 2002ap, M_V=-17.2 mag, is comparable to that of the type Ic 1997ef, but fainter than that of the type Ic hypernova SN 1998bw. The peak luminosity indicates an ejection of ∼0.06 M_☉⁵⁶ Ni mass.

We also present low-resolution optical spectra obtained during the early phases. The SIII absorption minimum indicates that the photospheric velocity decreased from ∼21 360 km/s to ∼10 740 km/s during a period of ∼6 d.