Riess, Adam GFilippenko, Alexei VLi, WeidongModjaz, MaryamTreffers, RichardHergenrother, CarlGrebel, Eva KSeitzer, PJacoby, George HBenson, PriscillaSchmidt, BrianWood, Peter2022-12-022022-12-020067-0049http://hdl.handle.net/1885/281505We present optical and near-infrared photometry and spectroscopy of the Type Ia SN 1998bu in the Leo I Group galaxy M96 (NGC 3368). The data set consists of 356 photometric measurements and 29 spectra of SN 1998bu between UT 1998 May 11 and July 15. The well-sampled light curve indicates the supernova reached maximum light in B on UT 1998 May 19.3 (JD 2450952.8^0.8) with B\12.22^0.03 and V \11.88^0.02. Application of a revised version of the Multicolor Light Curve Shape (MLCS) method yields an extinction toward the supernova of AV\0.94^0.15 mag, and indicates the supernova was of average luminosity compared to other normal Type Ia supernovae. Using the HST Cepheid distance modulus to M96 and the MLCS Ðtted parameters for the supernova, we derive an extinction-corrected absolute magnitude for SN 1998bu at maximum, MV\[19.42^0.22. Our independent results for this supernova are consistent with those of Suntzeff et al. Combining SN 1998bu with three other well-observed local calibrators and 42 supernovae in the Hubble Ñow yields a Hubble constant, H0\64 km s~1 Mpc~1, where the error estimate incorporates possible sources of systematic uncertainty including the calibration of the Cepheid period-luminosity relation, the metallicity dependence of the Cepheid distance scale, and the distance to the LMC.E. K. G. gratefully acknowledges support by Dennis Zaritsky through NASA LTSA grant NAG-5-3501 and by NASA through grant HF01108.01-98A from the Space Telescope Science Institute, which is operated by the Association of Universities for Research in Astronomy, Inc., under NASA contract NAS5- 26555. This work was also supported by NSF grants AST9528899 (R. P. K.), AST-9417213 (A. V. F.), and AST-9417359 (P. J. B.), as well as through an NSF Graduate Research Fellowship (S. J.).application/pdfen-AU© 1999. The American Astronomical SocietyDistance scaleGalaxies: individual (M96)Galaxies: photometrySupernovae: individual (SN 1998bu)The type Ia supernova 1998bu in M96 and the Hubble constant199910.1086/3132752021-11-28