Fan Mountain Observatory 31-inch Telescope Instrumentation

The 31-inch telescope is a general use reflector originally used with photomultipliers and a photographic plate specrograph. Currenty extensive hardware upgrades and instrumentation efforts have been completed, transforming the observatory into a more modern research facility capable of IR imaging and polarimetry . The telescope has two secondary mirrors allowing for either an f/16 or f/32 beam. The f/16 beam produces a 16.9 arcsec/mm focal plane.

Instrument Description Specs Website
Notes Status
EYE 2-inch Eyepieces NIR Specs FanCam Webpage A Operational
Fan Cam Fan Mtn. NIR Camera NIR Specs FanCam Webpage B Operational


A. One of the uses of the 31-inch is for public eyepiece observations during twice yearly Fan Mountain Public Nights. There are curently three eyepieces available: a 20mm Nagler, a 35mm Panoptic, and a 50mm Plössl.

B. In December 2004, FanCam saw first light on the 31-inch telescope and is now fully operational as a near-infrared imaging and polarimetry system. Please see the project webpage for more information.


The 31" NIR Camera system has a number of 1-inch filters for use. For more information see:

Fan Mountain Filters Webpage