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Operating Modes

The SPI instrument has only one mode for normal observations. All scientific observations with SPI are done in the so-called photon-by-photon mode with a high temporal resolution. In this mode the scientific information is collected and transmitted to the ground for each single detected photon.

If the SPI telemetry is continuously overflowing due to background radiation that is higher than expected or due to a strong solar flare, the instrument can be operated in a degraded science mode (TM emergency mode). In this case, the single detector events are binned on-board, and downloaded in the form of spectra. Thus the time information of each single photon is lost, but the analysis software is still able to handle the data in order to produce spectra and images as described in this document. The maximum data generation rate in this mode will be about half the rate for the normal photon-by-photon mode.



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