ARCADIA ASTRONOMICAL OBSERVATORY

Telescopes

Celestron C14  SCT

 

Telescope optics

 

The telescope has two modes of operation:   The original C14 is configured as a classical Schmidt-Cassagrain with an objective diameter of 14 inches or 350 mm and a focal length of 3910mm which works out at f/11 focal ratio.  Lumicon  ‘Giant Easy-Guider’  can be used as a focal reducer to f/7.1.  Focal length 2520mm.  In this configuration the field of view on the Kodak KAF8300 chip used in the SBIG 8300 CCD camera is 24.7’x18.7’.

 

 

The Starizona HyperStar kit converts the original SCT optics to something akin to a Schmidt telescope configuration. The original secondary mirror is replaced with a special lens resulting in the focal plane and the camera being in front of the telescope. In this configuration the focal length is 686mm and the focal ratio is f/1.9.  The field of view on the same camera is 91’ x 69’ (or 1.51 x 1.14 degrees).  Obviously in this configuration the Celestron C14 is not suitable for visual use. 

      ORION 102mm ED Refractor

 

 

The Orion 102mm refractor OTA was originally used as a high sensitivity guide scope required for automated survey runs where bright stars may not always be found in small fields.

It has been replaced with a 6 inch reflector for even more sensitivity.

 

The refractor is now used with a Sky Watcher HEQ5 Pro goto mount as a portable field scope.

 

C14 Fork Mount

 

 

 

Modification added to original fork mount

Optical diagram of standard Celestron  Schmidt-Cassagrain configuration

Optical diagram of Starizona HyperStar (or Celestron FastStar) configuration

 

Sky Watcher 150 (6”) reflector  guide scope

 

The PEC system is not good enough for long exposure imaging. For this purpose a 6 inch (150mm) Newtonian telescope (Orion 150mm) is mounted on the main scope with a guide camera.  The SBIG model SG4 “stand alone” autoguide camera is used.  The SG4 is able to select a guide star automatically on a push button command and start guiding. The SG4 guiding output is via an ST4 compatible RJ12 socket that guides the telescope via the hand controller remote control interface.  To enable automated remote operation, hardware modifications were added to the SG4 to read the status of LEDs and to initiate/stop autoguiding remotely.

 To contact us:      | E-mail: andras@arcadiaobservatory.org