16495

This program is a program to measure the change in the spectral resolution for the G130M-1222 and G160M-1577 settings at 7d_comma comma 9d_comma comma 11d_comma on the FUV detector as an exploratory program for Lifetime Position 6 (LP6). Knowledge of the COS line spread functions (LSFs) is critical for users to evaluate the feasibility and S-N requirements of their observations and to perform line profile fitting. It is not known what the spectral resolution is at and above 7d_comma comma and we need to know how it changes as we move up the detector in order to optimize the placement of LP6 and future LPs. To do so comma we will acquire COS FUV G130M-1222 and G160M-1577 spectra of the SMC star AzV 80 comma using two FPPOS to optimize the S-N whilst keeping overheads (due to split-LP-wavecals) at a minimum. Once all FPPOS settings are combined comma our observations will reach a S-N of 42-resel. We will test whether previous STIS E140M spectra of AzV 80 convolved with model COS LSFs at LP2 (the nearest calibrated lifetime position on the detector) can reproduce on-orbit observed COS FUV spectra of the numerous ISM lines toward AzV 80 at three different detector positions of +7d_comma comma +9d_comma and +11d_comma. We will be able to measure the relative change in the spectral resolution comma and unexpected larger variations in the COS LSFs larger than 15%. For simplicity comma we will use LP2 HV values of 173-175 (A-B) for all exposures. This strategy is based on several earlier programs (LP4 resolution programs 14842 and 15366) comma which executed successfully. Azv80 is used instead of the usual target for resolution programs (Azv75) becuase the visibility windows of Azv75 are too small. The depth of absorption features in Azv80 are comparable to those in Azv75.