[Previous] | [Session 38] | [Next]
A. Bonanos (Wellesley College), P. Garnavich, E. Schlegel, S. Jha, P. Challis, R. Kirshner (Harvard-Smithsonian CfA), K. Hatano, D. Branch (U.~Oklahoma)
We analyze photometric and spectroscopic observations of the supernova SN 1999by in the spiral galaxy NGC 2841. CCD images were taken with the 1.2 m telescope and spectra with the 1.5 m Tillinghast telescope at the Fred Lawrence Whipple Observatory in Arizona. SN 1999by reached maximum in B on UT 1999 May 10 (JD 24501308.5 ± 1) with B=13.80 ±0.02 and V=13.36 ±0.02, as indicated by 20 photometric observations between May 6 and June 21. The light-curves obtained in the U, B, V, R and I filters were compared to the templates of the subluminous type Ia SN 1991bg. SN 1999by appears very similar to SN 1991bg; it has \Deltam15(B)=1.87, versus 1.93 for SN 1991bg, making SN 1999by one of the most sub-luminous type Ia supernovae ever observed. The ratio of the spectral lines at 580 and 615 nm is small, consistent with being under-luminous. Models indicate that the spectrum contains deep titanium absorption bands, especially in the blue.