Performance of the HST Cosmic Origins Spectrograph FUV Channel at Lifetime Position 3

Oliveira, Cristina; Becker, George; Debes, John; Ely, Justin; Fox, Andrew; Jedrzejewski, Robert; Lockwood, Sean; Massa, Derck; Monroe, TalaWanda; Peeples, Molly; Penton, Steven Victor; Plesha, Rachel; Proffitt, Charles; Roman-Duval, Julia; Sahnow, David; Sana, Hugues; Sonnentrucker, Paule G.; Taylor, Joanna; Walborn, Nolan
IAU General Assembly, Meeting #29, #2257613 (2015).


The efficiency with which the Far Ultraviolet (FUV) detector of the Cosmic Origins Spectrograph (COS) on the Hubble Space Telescope (HST) detects photons declines with usage, a phenomenon known as "gain sag". To overcome this effect, the location of science spectra is periodically moved to a new pristine location on the detector (i.e., lifetime position), leading to small changes in the performance and calibration of the instrument. Here we provide an update on the results of the calibration program executed after the move to COS/FUV lifetime position 3, which took place on February 9 2015. We focus in particular on the flux, flat field, and wavelength calibration, and discuss the LP3 spectral resolution.