OBSERVATIONS OF THE TYPE II-P SN-1991G IN NGC-4088

We present VRI photometry and optical spectra of SN 1991G in NGC 4088. The strong Ha P-Cygni feature observed in the early spectrum coupled with the shape of the light curve demonstrate that SN 1991G is of type IT-P (plateau), SN 1991G's plateau, which lasts approximate to 120 da ys, is longer than that of other well-observed SNe, We combine our pho tometry and spectroscopy to estimate the time of the explosion to be J D 2448280+/-3 (1991 January 23 UT), 26 days before our first photometr ic observation. The expansion velocity of the material at the photosph ere, derived from absorption lines in our spectra, of 5590+/-340 km/s at 22 days after the explosion is slower than that: observed for all t he SNe II studied by Schmidt rt al. [ApJ, 395, 366 (1992)] other than SN 1987A. We find that the bolometric luminosity of SN 1991G is lower than that of typical SNe II-P during both its plateau phase and expone ntial tail and find that SN 1991G ejected less Ni-56 than most other t ype II-P SNe. Using the analytical models of SNe II-P by Popov [ApJ, 4 14, 712 (1993)], we compare the explosion properties of SN 1991G to SN 1969L and SN 1992am, This comparison suggests that the explosion ener gy of SN 1991G was likely smaller than that of the others, and that th ere may be a correlation of explosion energy with the mass of ejected Ni-56. (C) 1995 American Astronomical Society.