Given the task definition and input, reply with output. In this task you will be given a text passage from a trivia quiz. You should choose the category this question belongs to from these categories: History, Science, Social Science, Fine Arts, Literature. You can only choose one category, so if in doubt, please choose the closest match.

Finding the quadrupole-to-monopole ratio of the correlation function of the space named for this quantity is used to find its namesake distortion parameter, symbolized beta. Mattig's formula is a particular instance of the relation between this quantity and angular size. Because the Sunyaev-Zeldovich effect is independent of this quantity, said effect is used to map galaxy clusters that have high values of it. The K correction is employed in surveys that use this quantity, which include DEEP2, 2dF, and CfA. One method of calculating this quantity involves finding the ratio of the scale factor in the (*) past to the current scale factor, and distortions in it include the Kaiser effect and the "Fingers of God". It is equal to 1089 for the CMB, which corresponds to reionization. This value, symbolized z, is negative for M81 because M81 is moving towards us. For 10 points, name this quantity found by dividing the difference between the observed and emitted wavelength and dividing by the emitted wavelength, which is a change in the observed wavelength from an object moving away from the observer.
Science