This task takes the output source lists from each OSW (filenames listed in input listFile) and combines them to form the whole-observation source list (outFile), which is the pipeline deliverable product OM observation source list. The OSW source lists will previously have been magnitude calibrated (in the instrumental system, task ommag) and have RA-DEC coordinates (task omatt)
This primarily involves identifying which source is which in each list, combining the positions from each pass-band/exposure to give a best estimate and a refined error, and calculating the optical/UV colours for those sources observed with multiple filters in both the instrumental and standard systems. The magnitudes in the OSW source lists are in the instrumental (natural) system, and a call to the CAL extracts the current colour transformation matrix, which is applied to the instrumental magnitudes to give magnitudes in the standard system. Other information (e.g. quality flags) is also propagated.
A new column (SRC-ID) is added to each OSW source list, containing the observation source list number for the OSW source.
The combined source list is sorted into ascending Right-Ascension order. For sources in a particular filter that the program has identified as being identical (using the parameter nsigma and the position errors of the sources), the average magnitude of the sources is computed from the averaged corrected count-rates, using equal weights.
