Moving Targets

For a moving target, it is possible to permit the telescope to track at sidereal rate, and adjust the telescope offsets for the motion of a slowly moving target, i.e. one that stays within the field within an observation group. Registration uses the revised offsets and in the mosaic the stars trail while the object does not, and so can be seen and measured more easily.

At present the ephemeris is via a pre-prepared text file, given by environment variable ORAC_EPHEMERIS, if defined, otherwise $ORAC_DATA_OUT/target_ephemeris.dat. See one of the moving-target recipes, say MOVING_JITTER_SELF_FLAT, for more details. Once the ephemeris is available as a web service, the file could become merely a backup; this would automate the process and so the observer would not have to prepare the file at altitude just before the epoch of observation.
[_ADJUST_OFFSETS_TO_MOVING_TARGET_]