Observatory Telescopes

[main instrument] 12.5-inch f/6 Newtonian Equatorial

The main instrument features optics by W.R. Parks Company in the form of a 12.5 inch diameter primary mirror with a 75.25 inch focal length and an elliptical 3.10 inch secondary mirror. The telescope tube and aluminum end rings, mounting clamp rings, and 8x50 finder were also purchased from W.R. Parks Company. The optical support system (secondary holder, spider, and mirror cell) were purchased from Kenneth Novak Company. The tube assembly required about one year to complete.

The heavy duty mounting was machined by Thomas Mathis Company from castings obtained when the company once known as Telescope World (Hayward, CA) was liquidated. The castings were for a mounting once produced by Telescope World and designated as their 12-HD mounting. The mounting was machined and shipped by Mathis over a period of a year after completion of the tube assembly.

Additional fine machining and a clock drive system was obtained from Precision Specialities (410-574-4806) of Baltimore. Machining included:

  • completion of the tangent arm assembly, including machined knurled knobs.
  • installation of a latitude adjustment turnbuckle.
  • hand brakes on both R.A. and Dec. axis including machined knurled knobs.
  • latitude adjustment screws on each of three legs plus teflon pads (not used in observatory)
  • safety stop at end of Declination axis to prevent counterweight from sliding off
  • polar motor assembly including 11 inch machined worm gear, stainless steel worm, and motor
  • clutch assembly and complete mounting of drive
  • electronic components (assembled later by owner)
The additional machining required another year and was performed 12 years after the mounting had been completed.

The 12.5 inch is used primarily for planetary, solar, and lunar observing, as well as video observations of asteroidal occultations and studies of galaxy clusters and any other needs (including deep sky) for which a clock drive is beneficial.

[closeup of pier] Close-up of Pier

The 8 inch diameter pier is placed over a smaller pier that is bolted to concrete. The outer pier is attached to the inner pier with four bolts, visible at the bottom of the image, in much the same way that a finder scope is attached to a mounting bracket. Machining to attach the bolts and thread the pier was performed by Winfield Welding & Repair (410-875-0475) of Westminster.

This photograph reveals the adjustments available when polar aligning the telescope. For rough alignment the four bolts at the bottom are loosened, the entire pier is rotated, and the bolts are re-tightened. For fine adjustment the four allen screws at the top of the pier are loosened, the cap is rotated, and the screws are re-tightened. The turnbuckle allows the cap to rotate a couple of degrees in either direction.

Other Instruments On-Site

[Tectron 20 0.5 meter f/5 Tectron "Classic" Dobsonian

This large 20 inch Dobsonian reflector was built by Tectron Telescopes of Sarasota, FL. The 100 inch focal length gives it a focal ratio of f/5.

In the photograph at left the telescope sits outside the dome of the historic 26 inch Clark refractor at the U.S. Naval Observatory in Washington, DC. Notice the B&L 4000 SCT attached to the altitude bearing for use as a visual guide scope.

The Tectron was purchased used and is employed exclusively for deep sky observing.

[Celestron 8 SCT] 8 inch f/10 Celstron Schmidt-Cassegrain (SCT)

This is a classical "orange tube" C-8 (painted black by its original owner). In June 2004 the observatory purchased it from the original owner who in turn had purchased it from the manufacturer in 1981. Because of this telescope, MTO now has a portable instrument for use when traveling to remote occultation expeditions, star parties, and anywhere a portable clock driven instrument with moderate aperture is needed. It came equipped with a field tripod plus wedge and motors on both R.A. and Declination axis. The instrument has many other potential applications as demonstrated by the long list of equipment that came with it:

  • Two-axis drive controller and AC/DC converter
  • full aperture solar filter
  • 50mm finder
  • dew shield & 12V dew zapper
  • photographic equpment:
    • extender tubes
    • off-axis guider
    • "piggyback" platform
    • guiding eyepiece with illuminated reticle
  • eyepices (25mm and 40mm Kellners)
  • footlocker case
  • variable polarizing filter
[Coulter Odyssey 8] 8 inch f/4.5 Coulter Odyssey (Dobsonian)

This Newtonian telescope on a Dobsonian mounting by Coulter has an aperture of 8 inches and a focal ratio of f/4.5. It is also equipped with a Tuthill 50mm finder. It makes a pefect children's telescope.

The Odyssey 8 was purchased used and is currently on permanent loan.

[Criterion RV-6] Criterion RV-6" Dynascope

This telescope is the classic RV-6 by Criterion Manufacturing Company. It is an equatorial Newtonian with an aperture of 6 inches and an f/8 focal ratio. Although purchased used, the telescope left its factory in Hartford, CT on December 15, 1960.

[Edmmunds 6-inch f/8 Newtonian] Edmund Scientific 6" f8 Newtonian

This telescope belongs to a local nature center and was brought to Marstown Observatory for a tune up and to have its optis cleaned.

[5 Astrophyiscs 5 inch f/8 "Starfire" Refractor

An Astrophysics 5 inch f/8 Starfire refractor is shown on the mount for the RV-6". The telescope was donated by a generous dairyman to the Westminster Astronomical Society of Maryland.

[BL 4000] Bausch & Lomb 4000 SCT

The Bausch & Lomb 4 inch is a long focal length Schmidt-Cassegrain telescope (SCT) with a focal ratio of f/11. It is small enough to fit under the seat in front on airplanes and has traveled to many locations.

The B&L 4000 was purchased new in 1986 and is used primarily as a travel telescope and platform for piggy back astrophotography.

[60mm Refractor] Focal 60mm Refractor

The 60mm refractor has a focal length of 710mm (f/11.8). It was manufactured in Japan by Focal for K-Mart. Received as a Christmas gift.

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