Skip to main content

31-inch Tinsley Reflector

The 31-inch (79 cm.) Tinsley reflector is located on Fan Mountain. The telescope is a general use reflector originally used with photomultipliers and a photographic plate spectrograph. Currenty extensive hardware upgrades and instrumentation efforts are underway to transform the observatory into a more modern research facility capable of IR imaging and grism spectroscopy. This upgrade and instrument project is funded through an NSF grant. Projects in the upgrade include: a drive system upgrade, a new IR Carmera, and an autoguider.

Due to the status of this upgrade project the 31-inch will only be avaialable for public nights, twice a year. For more information about the project or use of the telescope please contact Michael Skrutskie (

The 31-inch (79 cm.) Tinsley reflector is located on Fan Mountain. Here is some information about the telescope.


Primary 31 inches in diameter, 120-inch focal length, 6.25 inches thick,
  wt. = 368.8 lbs., the hole is 8.75 inches in diameter. All
  mirrors are Pyrex.
4X Secondary 8.48 inches in diameter, 1.75 inches thick. System focal length
  480 inches. f/16
8X Secondary 5.474 inches in diameter, 0.875 inches thick. System focal
  length 960 inches. f/32
Plate scale 16.9 arcsec/mm (calculated). Measured value = 16.2 (Zissel)
  to 17.5 (Rosenberg) arcsec/mm.
Limiting visual magnitude Estimated at approximately 16 mag. on the best nights.
Dome 24 ft. Observa-dome.


    Field Power
Finderscope 5" Maksutov 30' 75X
  3" finder 2-3 15X
Eyepiece Black 15'  
  25 mm. + Xfer system 2.75' 960X
  25 mm. 6' 480X
  12.7 mm. 2' 950X