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Session 95 - Cosmological Parameters and Large Scale Structure Formation.
Oral session, Friday, January 09
International Ballroom Center,

[95.03] The Peak Brightness of SN1974G in NGC4414 and the Hubble Constant

B. E. Schaefer (Yale University)

The light curve of the Type Ia supernova SN1974G (in NGC4414) is important because the Hubble Space Telescope has measured the distance to the host galaxy by means of Cepheid variables and thus the Hubble Constant can be derived. Light curves from the secondary literature are inadequate since the majority of data is misreported, the majority of the published data is overlooked, and the majority of all data is unpublished, while comparison star sequences have offsets of over half a magnitude. I have recovered and validated all data, remeasured the comparison stars, and performed light curve template fits. I find the observed peak B and V magnitudes to be 12.48\pm0.05 and 12.27\pm0.05, with a decline rate of Dm15 = 1.11\pm0.06. For EB-V=0.21\pm0.07, the unabsorbed peak magnitudes are B=11.62 \pm 0.33 and V=11.62 \pm 0.25. By the time of the Washington AAS meeting, the HST Key Project group will have completed their measure of the distance modulus to NGC4414, so that a value for the Hubble Constant can be derived for this supernova alone. Also, a review is presented of seven Type Ia events with Cepheid distances in U, B, V, I, and H.

Program listing for Friday