BUSCA was developed as a cooperative effort at the Astronomical Institutes of Bonn University as a common user instrument for the 2.2m telescope at Calar Alto observatory. The instrument was realized in part through grant 05 2BN114 of the Federal Ministery of Education, Science, Research and Technology (BMBF). It offers direct imaging of the same field in four colours simultaneously. It is based on dichroic beam splitters and four large area CCD systems.
Since the observing periode 2001/2002 observers can apply for observing time with BUSCA.
Find out more about BUSCA in the report about the first Calar Alto campaigns.
The dichroic beam splitters are made of plano-parallel glass plates operating at an angle of 45 degree. This causes astigmatism in the converging beam. An opto-mechanical layout was therefore choosen which cancels the astigmatism (to the greatest part) by the introduction of another plano-parallel glass plate of suitable orientation into the optical train. TEST a telescope/star simulator (f/8) has been build to verify the imaging quality of the optical setup and to prove the promising results of the optical design calculations.
The CCD control electronics and the data acquisition system will be able to master 4 CCD systems each having up to 4 read out channels (2x2 CCD mosaic or large CCD's with multiple read out amplifiers). However the first version of the instrument will be equipped with "conventional" 2kx2k LORAL CCD's one of which is a backside illuminated thinned device with high QE below 400nm. This part of BUSCA is closely related to the BOCCIA project.