Wavelength Calibration of the COS/FUV Cenwaves G130M/1055 and G130M/1096

We present revised wavelength solutions for the COS blue modes, i.e. central wavelength (cenwave) settings of G130M/1055 and G130M/1096 at lifetime position 2 (LP2). We utilized COS observations of two stars, AV75 and HD 93205, taken at the two cenwaves of interest, along with FUSE and STIS data of these stars. The dispersion solutions (dispersion coefficient and zero-point) of detector FUVA for both cenwaves were obtained by using AV75 observations. However, for FUVB, we used HD 93205 data to derive the dispersion coefficients while we used AV75 to obtain the zero-points. We updated the newly derived dispersion solutions to the DISPTAB reference file for LP2, which was delivered in September, 2020, for use by the COS calibration pipeline, CALCOS. With these new wavelength solutions, the internal accuracies of the blue modes solutions are within the target of ±3 pixels (~ ±9 km s1) like those of the other G130M modes. Offsets of ~5 pixels can occur for FUVB due to the lack of wavelength calibration lamp spectra.