Outline the measurements that must be taken in order to determine a value for the Hubble constant.

One estimate of the Hubble constant is 60 km s^–1 Mpc^–1. Cygnus A is a radio galaxy at a distance of 6.0×10⁸ ly from Earth. Calculate, in km s^–1, the recessional speed of Cygnus A relative to the Earth.

red shift used to measure recessional speed of galaxies;
named measurement to yield distance to galaxies (e.g. Cepheid variable, Supernova);
repeat for many galaxies/clusters of galaxies;
Hubble constant is gradient of speed–distance graph; {(any symbols used must be defined)

To award [3] reference must be made to galaxies in at least one of the marking points.

\(v = 60 \times \frac{{6.0 \times {{10}^8}}}{{3.26 \times {{10}^6}}}\);
=1.1×10⁴ km s⁻¹;