Today's lab builds on information you gathered last week about galaxies from galaxy zoo. A good number of galaxies in the Galaxy Zoo project have been studied in various other surveys, so at least some have information from the Sloan Digital Sky Survey (SDSS), the UKIRT Infrared Deep Sky Survey (UKIDSS), and other sources. Some of the galaxies you worked with may therefore have such things as absolute and apparent magnitude, and a complete spectrum. Today you will work with a selection of galaxies with these parameters identified, and can add in ones the class has found that also have this information available. You will take this information and use it to figure out the recessional speed of the galaxies in this small survey to see if they fit Hubble's redshift relationship. You can figure out the velocity in a very straightforward way by comparing how much known spectral lines are shifted with respect to the same lines derived from laboratory procedures on Earth (think of the atomic spectra lab). Distance can be tricky as it depends on knowing the absolute magnitude of each galaxy. But once distance is known the Hubble parameter can be calculated....or the other way around