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Session 2 - Applied History of Astronomy II.
Oral session, Sunday, January 14
Salon del Rey Central, Hilton

[2.07] The Hubble Constant Derived From Observations of Ancient Historical Supernovae

B. E. Schaefer (Yale)

Type Ia supernovae are a remarkably good standard candle and are bright enough to solve the Hubble Constant debate if only one or a a few could be calibrated in peak absolute magnitude. Until the recent measures of Cepheid distances to several host galaxies by the Hubble Space Telescope, the only supernovae for which the distance could be derived were the historical supernovae in our own Milky Way. As such, the peak brightnesses of four historical events (Kepler's Supernova, Tycho's Supernova, SN1006, and SN185) was crucial for measuring the Hubble Constant. New techniques have been applied; including use of the heliacal rise date reports and light curve template fitting. New results are that SN185 is unlikely to be a supernova, and is most likely a nova and comet P/Swift-Tuttle; SN1006 peaked at V=-5.0+-0.5 and is certainly a very subluminous Type Ia event; Tycho's Supernova may be a Type Ia event and implies Ho=66+-15 if it is; and Kepler's Supernova is certainly not a Type Ia event.

Program listing for Sunday