The personal preference of the author, if forced to calculate a luminosity from a flux or a distance from an angular size, is to use the value of H0 70 – 73 km s–1 Mpc–1 which is fast becoming standard. No one determination is individually compelling, but the coincidence of the most plausible cosmological determinations and some local determinations, together with the slow convergence of the one-step methods of gravitational lensing and the Sunyaev–Zel’dovich effect, is beginning to constitute a consensus that it is hard to visualise being overturned. Most astronomers, if forced to buy shares in a particular value, would be likely to put money into a similar range. It is, however, possibly unwise to sell the hedge fund on a 10% lower value just yet, and it is important to continue the process of nailing the value down – if only for the added value that this gives in constraints that can then be applied to other interesting cosmological parameters. Barring major surprises, the situation should become very much clearer in the next five to ten years.
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