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Article Contents

ABSTRACT

1.INTRODUCTION

2.DESCRIPTION OF THE KEY PROJECT

2.1.Goals

2.2.Choice of Target Galaxies / Observing Strategy

2.3.Key Project Archival Database

2.4.Photometry

2.5.Calibration

3.THE CEPHEID DISTANCE SCALE

3.1.Adopted Method for Measuring Cepheid Distances

3.2.Effect of Metallicity on the Cepheid Period-Luminosity Relation

3.3.Adopted Period-Luminosity Relations

3.4.New Revised Cepheid Distances

4.THE LOCAL FLOW FIELD

5.CEPHEID HUBBLE DIAGRAM

6.RELATIVE DISTANCE METHODS AND H₀

6.1.Type Ia Supernovae

6.2.The Tully-Fisher Relation

6.3.Fundamental Plane for Elliptical Galaxies

6.4.Surface Brightness Fluctuations

6.5.Type II Supernovae

7.COMBINING THE RESULTS AND A VALUE FOR H₀

8.OVERALL SYSTEMATIC UNCERTAINTIES

8.1.Zero Point of the PL Relation

8.1.1.NGC 4258: Comparison of a Maser and Cepheid Distance

8.1.2.Resolving the Cepheid Zero-Point Discrepancy

8.2.Reddening

8.3.Metallicity

8.4.Completeness / Bias Effects

8.5.Crowding / Artificial Star Tests

8.5.1.Contamination from Companion Stars

8.6. Does the Measured Value of H₀ Reflect the True, Global Value?

8.7.Overall Assessment of Systematic Uncertainties

9.H₀ FROM METHODS INDEPENDENT OF CEPHEIDS

9.1.The Sunyaev-Zel'dovich Effect

9.2.Time Delays for Gravitional Lenses

9.3.Comparison with Other Methods

10.IMPLICATIONS FOR COSMOLOGY

11.SUMMARY

12.APPENDIX A: MAGNITUDE-LIMITED BIAS

REFERENCES