Observing Solar System Objects

Solar system objects differ from most astronomical sources in that the proper motions are large enough that the object position changes in the course of an observation. When observing such objects, you should create a ATCASCHED file in absolute time mode to ensure that CAOBS correctly tracks the object. CAOBS has the ability to phase track an object with a non-sidereal rate. Note, however, the pointing centre used during a scan does not track the source (the pointing centre used is the mid-position of the object during the scan). Thus your scans must be short enough that there is not significant motion of the source within the primary beam during a scan (ATCASCHED does not check this).