Specific catalogues were provided that are included in the TCS upon start-up, where any of the standard stars (or field of stars) can be accessed at any time without the need to load in a catalogue or read-in the coordinates separately. Apart from the ease of use, this also allows for simpler ways to define scripts (e.g., a general scripts for standard star observations).
Current the post-processing system that analysis the imaging data is being developed further to also include a astrometric and photometric calibration.
Further investigation in to the reported zero point variation has shown this is not due to FASU shutter or any miss-alignment of the filter. Rotating the filter by 90 degrees between the 2 allow positions in the filter wheel slot does give significant differences in the flat field, but a factor 2 less and in a different direction than those reported. We have been able to show that the changes coincides with a change in position of some filters in the instrument, but it is still not clear what is the specific cause. Analysis of recent data show that the zero-point is stable.
Thomas Augusteijn 2009-05-14