The General Nathan Twining Observatory (GNTO) is really a story about community, rather than just about telescopes and viewing dark skies.

It’s a story about the community sharing its treasures and resources so that the whole community continues to grow. It’s a story about Lt. Col Bill Isengard, USAF (Retired) sharing a wonderful telescope and land being donated in honor of a father.

Around 1980 Wilma Isengard made a suggestion to her husband, Bill, an amateur astronomer, that has had a profound and long lasting effect on The Albuquerque Astronomical Society. Due to failing health, Bill Isengard was no longer able to use his 16-inch f/6 Cave-Astrola Telescope and the thought of this wasted instrument troubled him. Wilma suggested he donate the telescope to the Albuquerque Astronomers (now TAAS), a group he had belonged to for years.

Bill presented the Albuquerque Astronomers with a proposal: “Find a dark location and build a secure building to house the telescope and it’s yours.” This proposal began the development and ultimate creation of the General Nathan Twining Observatory.

In 1988 Nathan Twining Jr., after hearing of the need for an observatory site, offered to donate four acres of land southwest of Belen. In January 1989 TAAS accepted the donation of the four acres and ownership of the “Isengard” telescope. The new observatory was named after Nathan Twining’s father General Nathan Farragut Twining, who was a former Chairman of the Joint Chiefs of Staff under President Eisenhower, and who had passed away in 1982.

By June 1989 the first hand drawn map of the observatory site was published in the Sidereal Times and TAAS star parties began to be held there on a regular basis. On 31 March 1990 Bill Isengard, Nathan Twining Jr., and then TAAS President, David Finley, with shovels in hand and TV News cameras rolling, broke ground for the new observatory. A groundbreaking speech was given by George Pellegrino.

The dome, an old grain silo cap, was donated by former member Alan Otterson and arrived in September 1989. On 24 April 1990, construction began with the digging of the foundation. When construction funds started running low Nathan Twining Jr. made an offer to donate up to $5000 in matching funds. TAAS members donated $2,653 and construction continued.

An image of the Isengard telescope donated by Lt. Col Bill Isengard and an image of General Nathan Farragut Twining whose son Nathan Twining Jr. donated the land for the GNTO.

GNTO is a TAAS member only and operated observatory located south of Belen, NM (about 45 miles south of the Big-I). Located under beautiful dark skies, this dark-sky facility is available to TAAS members and their guests 365 days per year.

You don’t even need to own a telescope to observe at GNTO. TAAS members can use the 16-inch reflector in the main dome, borrow an on-site loaner telescope, or produce their own pictures of distant galaxies, nebulae, and star clusters!

GNTO Events are listed on the TAAS Calendar. The monthly events are an excellent opportunity to learn from other astronomers. Each of the monthly events is coordinated by an “Opener” who announces the event on TAAS_Talk and provides details on when the site will be open. You should contact the Opener for details concerning the event.

Special events are such as TAAS Fab 50, constellation tours, and training are announced via TAAS_Talk and scheduled on the TAAS Calendar.

The facility includes:

  • 22 Observing Pads
  • Two fixed piers
  • Cafe & Warmup Building (Cocina Galactica)
  • Bunking, Meeting, & Remote Imaging facility (ROOst)
  • On-Site Loaner Telescopes
  • Picnic Area
  • Lecture Area
  • Imaging Telescope, Observing Telescopes and Binoculars are listed below

Imaging Telescope

The imaging telescope is a 14-inch Celestron Schmidt-Cassegrain optical tube assembly. A HyperStar optical corrector for CCD camera use at f1.9 is mounted on the telescope. This configuration accommodates a 6 megapixel CCD-Labs one-shot color camera. An Orion 80mm short tube refractor is used for image guiding.

Image acquisition and processing is accomplished on a laptop running TheSky6 Professional, CCDSoft, and Nebulosity software packages.


Isengard Telescope

The Isengard telescope is a 16-inch f/6 Newtonian style telescope made by Cave-Astrola. It is mounted on an equatorial mount. The telescope was donated by amateur astronomer Lt Col Bill Isengard UASF (Ret).

The telescope is equipped with an Astrometric Systems tracking drive that can be controlled using a laptop. Nexus DSC Pro digital setting circles are also available for moving the telescope scope manually. The focuser has a motorized Feathertouch unit so that tube vibration is minimized when refocusing. A variety of 1.25-inch and 2-inch eyepieces and filters are available for use with the telescope.

16-inch Dobsonian

The 16″ Dobsonian telescope is a re-built Meade optical tube assembly on an improved mount. It is equipped with an NGC-MAX digital setting circle system. It has a finderscope and a Telrad. The base has wheels that allow easy movement of the telescope from the Main Dome building to the observing field. There is a Setup and Operations Guide for this telescope in the GNTO Files.


406mm aperture
1830mm focal length

15-inch Dobsonian

The 15″ Dobsonian telescope is a re-built Discover telescope. It uses the original mirror with a lighter optical tube assembly on an improved mount. It is equipped with an Argo Navis digital setting circles system. It has a finderscope and a Telrad. The base has wheels that allow easy movement of the telescope from the Main Dome building to the observing field. There is a Setup and Operations Guide for this telescope in the GNTO Files.


381mm aperture
1905mm focal length


10-inch Dobsonian

The 10-inch Dobsonian telescope is also called the “Pellegrino Telescope” because the tube was constructed and used by George Pellegrino.


Solar Telescope

The solar telescope is a Coronado Personal Solar Telescope (PST) mounted on a tripod.

Large Binoculars

The Astro-Vue RA-88-SA binoculars are 88mm binoculars that use a pair of 1.25-inch eyepieces mounted at a right-angle for comfortable viewing. The binoculars are used with a parallelogram mount.

GNTO Safety Information

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