Cosmic Background Explorer/FIRAS
Destriped Sky Spectra (Spectral Sky Maps)
There are three main Spectral Sky Maps: two low-spectral resolution products (FIRAS_DESTRIPED_SKY_SPECTRA_LOWF.FITS, and FIRAS_DESTRIPED_SKY_SPECTRA_HIGH.FITS), which cover the full FIRAS frequency range at 13.6041 GHz resolution; and a high-spectral resolution product called FIRAS_DESTRIPED_SKY_SPECTRA_HRES.FITS, which covers the frequency range 30 - 660 GHz at 6.9 GHz resolution. These files contain a spectrum at each pixel and were created by coadding spectra obtained from various FIRAS channel and scan mode combinations. Prior to coaddition, the observations made in different modes were calibrated to remove the instrument signature. "Destriping" is a secondary calibration step applied to compensate for unidentified instrumental offsets. The existence of such offsets is suggested by stripes that appear in an untreated sky map at a particular frequency.