Wavelength Calibration of the Cosmic Origins Spectrograph

Cosmic Origins Spectrograph (COS) calibration programs 11487 and 11474 were carried out during Servicing Mission Observatory Verification (SMOV) to characterize the wavelength scales of the FUV and NUV detectors, respectively. Science data were obtained with all the FUV (G130M, G160M, and G140L) and NUV (G185M, G225M, G285M, and G230L) gratings through the Primary Science Aperture (PSA), simultaneously with PtNe lamp line spectra, obtained through the Wavelength Calibration Aperture (WCA). These data were partially calibrated with the COS pipeline and then, in conjunction with STIS data of the same target, used to derive offsets between the PSA and WCA wavelength scales. These offsets are then used to place the dispersion relations derived from thermal vacuum 2003 (TV03) in the on-orbit frame of reference, so that correct wavelengths can be assigned to the on-orbit COS data.