Space Telescope Science Institute   3.2 HST Guiding Performance Chapter 4:  Cycle 16 Scientific Instruments

3.3 HST Observing Efficiency


HST's "observing efficiency" is defined as the fraction of the total time that is devoted to acquiring guide stars, acquiring astronomical targets, and exposing on them. The main factors that limit the observing efficiency are:

In recent cycles, the average observing efficiency in three-gyro mode had been around 50%. However, that value has dropped to < 45% in two-gyro mode. Of the usable observing time, about 90% is allocated to science observations, with the remainder devoted to calibration and engineering observations (<~10%), and repeats of failed observations (~2%).


 3.2 HST Guiding Performance Chapter 4:  Cycle 16 Scientific Instruments
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