Since the switch to STIS CCD Side 2 electronics (see
ISR 2001-03) on 2001-Jul-10, it has not been possible to
actively stabilize the CCD operating temperature, due to the
lack of a temperature sensor on Side 2. Therefore, to control
the thermal environment, a constant current is applied to the
CCD thermo-electric cooler. This, however, allows small
variations in CCD temperature. These variations are tracked
indirectly by a temperature sensor in the CCD housing, so that
temperature-dependent calibration can be performed.
The following plot shows the history of the CCD housing temperature since the repair of Side 2 in May 2009. The x-axis gives the date in years, while the y-axis gives the CCD housing temperature in degrees Celsius. The diamonds are the housing temperature as measured from the dark and bias calibration observations. This amounts to three points per day. The solid black (triangles very close together) curve is the sun time*solar intensity as a function of time. This curve tracks the orbital precession of HST and matches well the periodicity found in the housing temperature.
The following plot shows the history of the CCD housing temperature from the switch to Side 2
to the Side 2 failure in 2004.
The dots are the temperatures for each of the CCD observations. The filled
diamonds are the medians per calendar month.
If you'd like more information about the data these plots were generated off of, please contact the STIS team at STScI.
Last Update: 06/04/2012