16556

Monitor the spectroscopic sensitivity of the CCD using both low- and medium-resolution grating settings to reveal any contamination issues which might affect the spectroscopic throughput. This calibration program will monitor the spectroscopic sensitivity of CCD spectroscopic settings using the same high-declination calibration standard. Results will be ratioed to the first observations to detect any trends. Every four months comma the L-modes will be observed at settings which cover both the nominal position and the recommended E1 position which places the spectrum closer to the CCD readout. These visits comprise one orbit for each visit. This program also monitors the medium-resolution gratings comma with one visit. This visit takes observations at two central wavelength settings of G230MB and G430M comma at each of the nominal and E1 pseduo-aperture positions comma and at 1 central wavelength setting of G750M (with the addition of an observation at the pseudo-aperature position to that at the nominal position). CTE will also be verified.