SMOV Absolute Flux Calibration of the COS FUV Modes

Initial point source sensitivity curves are determined forthe COS NUV gratings: G230L, G185M, G225M and G285M. Observations through the PSA were ob tained of the standard star GD71 at all central wavelength settings of all the g In addition, PSA observations of the standard star GRW+70 ◦ 5824 were obtained at selected settings. Because the pipeline used at the time of the analysis extract ed BOA spectra incorrectly, BOA calibrations are not discussed here. The accuracy of the calibration is estimated to be � 2% for the medium resolution gratings, and somewhat less accu rate for portions of the G230L. We also examine the contributions of off-order light contamination on the observed spectra. We find this to be negligible for the mediumresolution gratings and for first order G230L spectra at wavelengths shorter than 320 0 ˚ A.