# Difference between revisions of "Power spectra"

This is the page regarding the HFI-based power spectra

We call intra-frequency checks those performed between detectors (or sets of) in the same frequency bands, which thus respond similarly to the sky emission. Interfrequency-checks on the other hand correspond to checks bewteen detector in different frequency bands, imposing further reliance on a sky model to perform the test.

## Intra-frequency checks

These compare the power spectra between various detector sets operating within the same frequency channel.the They see the same sky, up to color corrections due to their somewhat different spectral band passes. These corrections are rather small if one restricts the comparison to specifi portions of the sky, for instance dominated by extra-Galactic components, like it is done for extracting the CMB power spectrum in the likelihood analysis where \$f_{sky} \sim 0.4\$.

## Inter-frequency checks

(Planck) High Frequency Instrument

Cosmic Microwave background