17.5 Cycle 8 Calibration

The Cycle 8 calibration plan was modeled closely on the Cycle 7 calibration plan. Once again, supported modes were monitored for such things as sensitivity changes, flat field evolution, and dispersion solutions. No additional calibrations were taken for most available-but-unsupported configurations.

In addition to monitoring instrument health and safety and maintaining the overall calibration of STIS supported modes, our special goals were as follows:

1. to improve the imaging throughput calibration accuracy (to better than the current 5% systematic uncertainty);
2. to improve PSF characterization in imaging mode and in coronagraphic mode;
3. to improve CCD hot-pixel and bias subtraction;
4. to improve the CCD charge transfer efficiency (CTE) characterization for sparse fields at low count levels;
5. to calibrate the dispersion as a function of position for MAMA slitless spectroscopy with the L-mode gratings;
6. to characterize observations with the FUV-MAMA repeller wire turned off, with the aim of possibly making this available for Cycle 10. This should improve the spectral resolution at the expense of a ~35% loss of sensitivity.

The results of all the Cycle 8 calibration programs are presented in the close-out report STIS ISR 2001-04.