17.9	Cycle 12 Calibration

The Cycle 12 calibration plan continues the routine monitoring programs of Cycle 11, with reductions in observing time where less data or less frequent monitoring are now sufficient. As before, much of the program is devoted to producing timely darks, biases, flats, and sensitivity corrections, and to monitoring basic instrument characteristics and performance. Characterization of CTE remains a high priority, to support upcoming CTE correction of fluxes in extracted CCD spectra in the pipeline.

Additional or modified observations were made to meet specific needs in some continuing programs, and some new observations were made, as follows:

1.	CCD spectroscopic sensitivity was monitored somewhat more frequently so that dependence on detector temperature can be modelled more accurately, along with tracking temporal dependence.

2.	Deeper MAMA wavecal exposures were made to support physical modelling that will lead to better dispersion solutions.

3.	Spectroscopic observations were made of a star stepped along slit, achieving low signal and background levels, to improve our characterization of the large CTE losses that occur at these low levels.

4.

New “apertures” (target locations in existing apertures) were defined to improve observations high on the CCD detector (where CTE losses are less) and low on the FUV-MAMA detector (where dark current is less), and to provide a new coronagraphic aperture (see Section 12.10). The locations of the new apertures were verified.

The STIS Side-2 electronics failure occurred very early in Cycle 13, before the Cycle 13 calibration plan commenced. However, routine monitoring observations from the STIS Cycle 12 calibration plan were still ongoing, and provided the necessary calibration data for the Cycle 13 STIS GO data that was collected.