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31-inch Telescope

gr/31inch.jpg

31-inch telescope at Anderson Mesa, near Flagstaff, AZ

Built by AstroMechanics, the 31-inch reflectorwas originally owned by NASA and then was operated on loan from NASA by USGS. In order increase the telescope's use for lunar and planetary work and because of Lowell's enhanced capability to maintain the telescope, it was transferred in 1972 to Lowell Observatory's custody (remaining on the same spot on Anderson Mesa where it was built). Equipped to operate robotically, the 31-inch telescope is used by Lowell astronomers and for about a third of the time is shared by astronomers and students as part of the National Undergraduate Research Observatory at Northern Arizona University.



Lowell Telescope Specification chart

Perkins 72" Hall 42" LONEOS 31" 21"
Longitude 111° 32' 09.3" 111° 32' 07.9" 111° 32.2' 111° 32' 09.0" 111° 39' 59.2"
Latitude +35° 05' 48.6" +35° 05' 48.3" +35° 05.8' +35° 05' 54.6" +35° 12' 10.4"
Altitude 7236ft. (2206m) 7236ft. (2206m) 7236ft. (2206m) 7243ft. (2208m) 7260ft. (2213m)
Dp 72" (1.8m) 41" (1.04m) * 31/29.5" (0.79/0.75m) 20.78 (0.53m)
F/# 17.5 8.06 * 15 15.9
EFI 1256.5" (31.93m) 330.39" (8.392m) * 464" (11.78m) 332.5" (8.44m)
Scale ("/mm) 6.45 24.58 * 17.5 24.3
BFI 51.5" (1.30m) 29.9" (0.759m) * 25" (0.63m) 20" (0.51m)
Fp/# 4.18 4.05 * 5.0 3.4
FLp 300.6" (7.635m) 166.06" (4.218m) * 155" (3.94m) 70.0" (1.77m)
Dsa 16.3" (0.41m) 16.6" (0.422m) * 9.0" (0.22m) 4.6" (0.12m)
Is 284.1" (7.22m) 130.43" (3.313m) * 134.9" (3.43m) 72.7" (1.85m)
Os 68.0" (1.72m) 65.51" (1.664m) * 45.1" (1.14m) 15.3" (0.39m)
Ms 232.6" (5.91m) 100.56" (2.554m) * 109.9" (2.79m) 54.7" (1.39m)
mag 4.2 1.990 * 3.0 4.7
K1 -1.0 -1.306 * -1.00 -1.00
K2 -3.65 -14.945 * -5.01 -3.35

1) Longitude and latitude are good to about 0.2.
2) The altitudes are good to about 1 meter.
4) The Hall F/8 is a Ritchey-Chretien telescope.
5) The 31inch primary if F/5. However, it is stopped down to 29.5 inches.
6) Only the Hall F/8 has a known optimum back focal distance.
7) The conic constant is defined such that 0 is a circle and -1 is a parabola.
8) Dsa is the diameter of the axial cone at the secondary. The diameter of the secondary is 1 to 2 inches larger than Dsa.

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