Joint Astrophysics Colloquium

The Carnegie Hubble Program

Victoria Scowcroft

Observatories of the Carnegie Institution of Washington

The Carnegie Hubble Program is a Warm Spitzer program designed to measure the local Hubble constant to an accuracy of 2%. We are constructing a single instrument distance ladder based on parallax measurements of local Cepheids, extending out beyond the Virgo cluster. I will discuss the work we have completed to date on Galactic and Local Group Cepheids and how we tie this in the more distant galaxies using the Tully Fisher relation. This work has lead to a calibration of the Hubble constant with a systematic uncertainty better than 3%. Finally, I will introduce our new program - The Carnegie RR Lyrae Program. This program will produce a complementary population II calibration of the local distance scale, allowing us to check our results independently of the CHP data.