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Algorithm

Exposure correction is performed by dividing the values in the input data by an exposure time. CORRECT attempts to get an exposure time from three sources, in order,

The EFF_EXPOSURE component of the input dataset header
The EXPOSURE_TIME component of the input dataset header
From the user using the TEXP parameter

Dead time correction is only performed if a valid LIVE_TIME structure is defined in the dataset. This contains 3 components, the ON, OFF and DURATION. The first two list the start and stop times during which the detector was exposed to a "source". The last component is the time for which the detector would actually have been able to register a count. DURATION(i) is generally less than OFF(i)-ON(i) for photon counting detectors due to dead time in the counting electronics. CORRECT applies dead time correction slightly differently depending on whether the input dataset contains a time axis.

If no time axis is present, the sum of (OFF-ON)/DURATION provides a dead time correction factor which is the same for every bin. The presence of a time axis causes this correction to be applied in for each time bin individually.

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