Telescopes at Goldendale Observatory

Primary Instrument

Goldendale Observatory State Park houses a 24.5 inch (0.6 meter) reflecting telescope in the South Dome, which was built by amateur astronomers at Clark College in the late 1960's. The telescope is carried on a computer-controlled equatorial mount. Attached to the 24 inch telescope is a 6 inch (150 mm) refractor telescope.

At the recommendation of the Friends of Goldendale Observatory President, the optical configuration was revised from a Cassegrainian to a Newtonian, which was originally also an option for the telescope, and which is much better suited for both visual and photographic imaging use. Cassegrainian focal positions are usually intended for research instrumentation and purposes such as spectroscopy - which was only one of the intended purposes of the telescope.

Given the large changes in temperature experienced at the observatory, the Friends President also recommended replacing the original Pyrex mirror with one that uses a modern thin mirror made from low-expansion fused quartz and having much better thermal stability. The observatory's Director chose another mirror vendor with a risky cellular structure that failed after several attempts at casting.

A fused quartz mirror was eventually obtained, again at the advice of the Friends President, but the non-refundable $12,000 deposit made on the cellular mirror was lost.

The redesigned pier and base plate allow for more accurate tracking of the telescope. This enables better viewing and long exposure imaging with the new optics.

The upper end of the telescope has a large diameter lazy susan rotating bearing assembly to hold the new secondary mirror and focuser, which allows for better reaching of the eyepiece for viewing. The bearing was donated to the Observatory by FOGO.

Note: FOGO had no involvement with the "unique" cantilevered photographic enlarger bellows focuser implementation, or the oversize secondary mirror and extended focal position chosen for the new primary mirror, which can degrade the performance of the otherwise excellent primary mirror.

Other Instruments

The North Dome is home a highly regarded Celestron 14 f/11 0.35 meter Schmidt-Cassegrain telescope mounted on a high-end Mathis MI 500 fork mounting with Ed Byers precision drive gears and stepper motors. FOGO found and helped obtain this instrument to Goldendale Observatory - at a substantial savings to Washington State taxpayers - from central California.

Attached to the C14 is a Lunt Solar Systems LS152THa (152 mm - six inch) Solar Telescope; the largest continuous production Hydrogen-alpha solar telescope in the world. Popular with many individuals and educational institutions, FOGO was responsible for encouraging the obtaining this instrument for the Observatory. It replaced a smaller 60 mm H-alpha solar telescope that the Friends had also recommended purchasing years earlier in order to bring enhanced daytime viewing and education opportunities to the Observatory. This instrument is utilized during afternoon presentations for solar video output onto displays and projectors throughout the facility.

For outdoor mobile use on sidewalks and decks during evening presentations, the Observatory also features an Orion 14 inch (0.35 meter) f/4.6 Dobsonian telescope donated by a FOGO member, and a number of other portable instruments, including astronomical binoculars.