Abstract
An optical imaging system for the Observatorio Astronómico Nacional at San Pedro Mártir is described. The system includes a fixed wheel with 4 polarizers, a sliding bench for focal reducers, an interchangeable wheel for up to 8 interference filters and a rotating flange. Focal reducers are a couple of triplets optimized to work in the blue and red ranges, increasing the plate scale 1.6 times, yielding unvigneted fields of view of 14.9' and 8.4' for the 84 cm and 1.5 m telescopes, respectively. Control is carried out through an embedded IBM-PC compatible computer. The interface card is connected through the IDE port of the PC. The control and user interface programs are both written in C++. Two user interfaces were developed: one runs under WINDOWS, the other is an HTML page accesible from any web browser.
