"g" == greywolf42 writes:

g There are about a couple of dozen galaxies where we have the
g ability to resolve Cepheid variables -- which are our only reliable
g distance "standard candles" (...). All distances to other galaxies
g are measured by assuming the BB and Hubble constant.

I feel obliged to point out that the distance to the galaxy NGC 4258
has been determined by triangulation (i.e., parallax) of the water
masers in its core.

There are of course assumptions in this method as well, e.g., what is
the lifetime of the maser spots and are the same spots being measured
from epoch to epoch. Nonetheless, if one makes reasonable
assumptions, one ends up with a distance of something like 7 Mpc.

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