Because of the importance of the stabilisation of the signal (see Section 4.4), measurements were often begun with a number of so-called stabilisation exposures, with the camera on-target and in the selected configuration, and allowed to adjust to the new input flux level. We note that the stabilisation exposures are retrieved, together with the science exposures, from the ISO Data Archive and are useful for data analysis purposes. In a raster measurement, stabilisation readouts were only done at the first raster position.
It was also possible to programme, within the AOT, certain calibration measurements of one's own, for example a dark measurement or a measurement of the internal calibration device (ICD). This was, however, strongly discouraged after launch as it would have disrupted the stabilisation of the signal. The general facility calibration was sufficient to calibrate the scientific measurements.