A study was made to look for possible improvements to the current system. One conclusion from the report was that a significant improvement could be made by changing the standby pick-off mirror which has a reflectivity of only 62%. It was impossible to remove the coating off the existing mirror so it was decided to acquire a new one. Specification were defined and a mirror ordered.
The most obvious improvement to the instrument is a change of the very low efficiency detector. A 2kx2k device with 15m pixels would be the best solution in the current situation, providing the maximum 3.6 arcmin squared field-of-view with a sampling of 0.11 arcsec per pixel compared to the current 3 arcmin squared sampled at 0.176 arcsec. Depending on the device, the expected gain in efficiency with a new CCD would be a factor 1.5 in the red and a factor 2 in the blue.
Further improvements, allowing for a larger field-of-view would require modification of the filter mechanism and/or the pick-off mirror unit, were also specified in more detail.
Thomas Augusteijn 2006-02-02