Colloquium on 12 September 2013
The SH0ES project: H0 to 3% and beyond


Title: The SH0ES project: H0 to 3% and beyond
Speaker: Lucas Macri
Date: Thursday, 12 September 2013
Time: 16:00 - 17:00
Venue: SAAO Auditorium


The SH0ES project (P.I.: Adam Riess) aims to obtain increasingly more precise
and accurate determinations of the Hubble constant using type Ia supernovae,
calibrated via near-infrared observations of Cepheid variables. We minimize
sources of systematic uncertainty by building a robust, differential distance
ladder that uses the same telescope and camera (HST and WFC3) for all
observations. The ladder is anchored on the “maser galaxy” NGC 4258, the
Milky Way and the Large Magellanic Cloud. Our most recent determination of
H0 has an uncertainty of 3.3% (Riess, Macri et al. 2011, ApJ 730, 119).

I will review our progress to date and present results from the current phase
of the project, designed to yield a 1.9% determination of H0. This will be
achieved by doubling the SN calibrator sample and by obtaining high-quality
parallaxes to an additional 11 Milky Way Cepheids.

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