The Jacobus Kapteyn Telescope

The JKT has a 1.0 metre diameter parabolic primary mirror with a focal ratio of f/4.6. The telescope is equatorially mounted, on a cross-axis mount, which can be used East or West of the pier. There are two Cassegrain optical configurations, with interchangable secondary mirrors:-

• An f/8.06 Harmer-Wynne system with a spherical secondary mirror and afocal doublet corrector, with a flat focal plane, and a field of view of 90 arcmin diameter. This has been used for wide field photographic astrometry. The wide field camera is NOT currently available as a common user instrument.
• A more commonly used hyperbolic secondary, which gives a conventional Cassegrain optical system with a focal ratio of f/15.0, and a curved focal surface 34 arcmin in diameter. This focal station is equipped for direct CCD imaging, where the field curvature over the size of current CCDs is not a problem.