Sets of basic data for determining the absolute calibration of the detectors were obtained at the beginning and end of each MIPS instrument campaign. Various types of well-studied astronomical sources are observed for this purpose (see section 4.1.2). These observations did not need to be taken more frequently because of the stability of the stimulator output over time, and the exhaustive use of stimulator flashes built-in to all MIPS observing templates. To keep the observatory observation efficiency at a maximum, ''unnecessary'' calibration data acquisition was avoided.
Because there is contamination on the pick-off mirror that feeds MIPS (see section 7.1.1), each campaign included sets of scan-mirror-position-dependent flat fields for the 24 μm array.
· If not already on for IRS, switch on the Combined Electronics and other MIPS electronics requiring specific turn-on commanding.
· After the required warm-up time (0.5 hour), proceed with routine calibration measurements.