The quasar 3C 273 is moving away from the Milky Way at a velocity
of 47,500 km/sec.

(a) What is the redshift of 3C 273?  Compute the redshift using both
versions of the Doppler equation, to see if relativistic effects matter
at this velocity.

(b) If the Hubble constant H = 70 km/s/Mpc, how far away is this quasar?

(c) If the flux from this quasar is  3 * 10^(-13) Watts per square 
meter, what is the luminosity of 3C 273?  How many years would the Sun have
to shine to produce the energy that 3C 273 produces in one second?