Cycle 9 Calibration

The STIS Cycle 9 calibration plan has been modeled closely on the Cycle 8 calibration plan. Supported modes are to be monitored for items such as sensitivity changes, flat field evolution, and dispersion solutions. No additional calibrations will be taken for available-but-unsupported instrument configurations. Observers wishing to use non-standard instrument configurations should assess their specific calibration needs and include time in their Phase I proposal for any additional calibrations that are required.

In addition to monitoring instrument health and safety and maintaining the overall calibration of STIS supported modes at the accuracies as established during Cycles 7 and 8, a few special calibration programs have been added for Cycle 9, with the following goals:

1. To improve the Charge Transfer Efficiency (CTE) characterization for the CCD, i.e., its dependences on time, source intensity, source nature (point source vs. extended source), and sky background;
2. To quantify the remanence intensity level after over-illumination of the CCD as a function of time after saturation and of number of readouts after saturation. The remanence level may well have increased since STIS was installed on HST due to the degraded CTE;
3. To improve PSF characterization for the CCD in imaging mode, coronographic mode, and spectroscopic mode as a function of source color;
4. To improve the dispersion solutions for the reddest settings of the G750M grating;
5. To model the ghosts (which are caused by multiple reflections in the CCD window) in the G750M grating mode.

More detailed information on the STIS Cycle 9 calibration program, including all proposal ID numbers and titles, can be found on the STScI STIS web site under "Cycle 9 Calibration Plan".