Method

Each of the user-supplied list of datasets is checked against the first to see that its structure is similar. The output dataset is formed using the total lengths of the lists found in the input datasets.

Datasets with different pointing directions can be merged - the output file will have the orientation of the first image. Only the X_CORR and Y_CORR lists are affected (if present).

Most header components (and the instrument response) are copied from the first input dataset. The exceptions are:

BASE_MJD,BASE_UTC,BASE_DATE,BASE_TAI :

These 4 header parameters, and all other timing information in the input datasets are adjusted to the origin defined by the dataset with the earliest BASE_TAI.

EXPOSURE_TIME, OBS_LENGTH :

Are calculated from the sums of the values in the input datasets. Only written to output if present in all inputs.

LIVE_TIME:

Live time slots from the inputs are merged and sorted into time order. Any duplicate slots are removed.