
Why do I see negative values in Planck intensity and covariance maps?
Posted by Peregrine McGehee on 16 June 2014 03:24 PM
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While both the intensity and covariance quantities presented in the Planck all-sky maps are, by definition, positive, there are situations in which you will see negative values. o In regards to the Planck intensity maps: To begin with, the Planck all sky intensity maps do not have the Cosmic Microwave Background [CMB] subtracted. The CMB subtracted maps can be found together with the component separated CMB maps, for example at: However, negative values in intensity (but not covariance) can occur because of noise. o In regards to the Planck covariance maps: Covariance values should not be negative. but the negative values in the covariance are HEALPix bad values, i.e. -1.63750E+30. | |
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