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The ARIES Baker-Nunn Schmidt telescope (BNST) project was initiated during 2005 to use its wide area imaging capabilities for numerous scientific purposes with modern CCD detector. The project of optical refurbishing and new mechanical designing had been taken up under ARIES technology development program. It has a primary mirror of 50 cm diameter.  

50 cm Schmidt telescope.

The CCD camera is located at the prime focus of ARIES BNST inside the telescope at about 521.77 mm from the primary mirror.  The f/1 fast optics covers 4 degree circular field of view with the meniscus lens placed between CCD detector and primary mirror at 345 mm from the primary.   The basic optical design of the Baker-Nunn camera uses a three element corrector to produce an extremely wide field of view (5° x 30°) across a curved plane at the prime focus. The field flatter lens of 55mm diameter,  at a distance of 1.66 mm from the CCD chip, is used to flatten the curved field. The CCD detector is a front illuminated Kodak KAF-168003 chip with 4096 x 4096 pixels, each 9 micron size. Since the CCD is mounted inside the tube,  therefore a thermoelectric cooling system with the fan assisted air cooling system which operates 55-60° C  below the ambient temperature.


The telescope and detector parameters are given in the table. 

Telescope diameter 80 cm
Clear aperture 50 cm
Plate scale 412’’/mm
Readout noise of the detector 10 e–/ADU
Dark current of the detector 1 e–/pixel/sec
Pixel size 9 μm
Saturation limit 100000 e–
Effective transmission 0.246
Sky brightness in V 21.8 mag/arcsec2

Scientific programs like study of variable stars, Asteroids and Near-Earth-Objects, detecting of extra solar planets through transit method,  transient objects like GRBs and supernovae, and imaging of large star clusters can be suitable accomplished with such a wide-field imaging telescope.