The Search for Ho

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Suppose we now have determined and calibrated the Cepheid Period-Luminosity relation and have used it to find distances to some nearby galaxies. How can we proceed from there?

The Tully-Fisher Physics or Black Magic?

Current Limitations in the determination of Ho:

• (m-M) LMC: (18.35 -- 18.50). Cepheid vs. RR Lyrae zeropoint discrepancy; SN 1987 Ring
• M100 and depth of the Virgo Cluster
• Rotation Curves and their details --> fundamental limits in TF relation
• SN Ia What is their Luminosity Function?

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