Supernovae and the large-scale value of H0

The most secure route for the determination of Ho over scales out to similar to 30 000 km s(-1) is provided by blue SNe Ta. They are nearly perfect standard candles with luminosity scatter of 0.(m)1 (after small corrections for differences in decline rate and color) as demonstrated by their exceptionally tight Hubble diagram tin B, V, and I). Inserting the absolute magnitude M-B,M-V,M-I of SNeIa, which is fixed by eight SNeIa in galaxies with known Cepheid distances, yields H-0 = 58.5 +/- 6.3 (2 sigma). Brightest cluster members, TF distances, and D-n-sigma distances can be used to construct Bubble diagrams of clusters of galaxies. They have larger scatter than SNeIa, but are still useful. The Hubble diagrams can be calibrated by the Virgo, Fornax, and Coma clusters, respectively, whose distances are well determined by Cepheids, SNeIa, the TF relation and other less secure methods. The mean result from four cluster Hubble diagrams is H-0 = 59 +/- 3 (+/-6 for systematic errors) over scales of greater than or similar to 10 000 km s(-1). The above SNeIa lie predominantly in field galaxies. Other methods can be used to determine distances of field galaxies, like the TF or D-n-sigma relations, but their larger intrinsic scatter invites severe selection effects (Malmquist bias) which limits their range to less than or equal to 8000 km s(-1). A literature compilation of Ho determinations, which are carefully corrected for selection effects, suggests H-0 = 55 +/- 6. Of the several physical methods to determine distances and H-0, the lensed quasar PG 1115-080 gives the most significant result at present, i.e. H-0 < 60.