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Posted on: June 28, 2016

16-036 Large telescope at Goldendale Observatory offline for service this summer

OLYMPIA – June 28, 2016– The Washington State Parks and Recreation Commission announces that the large telescope at Goldendale Observatory State Park Heritage Site will be out of service for most of the summer while it undergoes a much-needed upgrade.

Crews will begin dismantling the telescope on Wednesday, June 29. State Parks estimates the large telescope will be back in service before fall. The telescope is one of the nation’s largest public telescopes, and the work will update it to current state-of-the-art standards that include research-grade cellular optics and capacity for astrophotography.

The park will remain open during the time the telescope is out of service, but park hours and show times are reduced. Park hours are now 3:30 to 11 p.m., Wednesday through Sunday. The park will offer two shows—at 4 p.m. and 8:30 p.m.—on these days. The afternoon shows will focus on the sun, as viewed through the site’s solar telescope. Evening shows will be conducted with portable telescopes.

Telescope upgrade

The 24 ½ -inch telescope is being removed so that a new concrete pedestal and Azimuth adjustment plate can be constructed in the observatory dome. During the upgrade, the telescope will be disassembled and stripped of its thick and aging paint. It will then be powder coated with modern light-absorbing materials. A new drive control system also will be installed, and several small mechanical upgrades will be completed.

Once the telescope is reassembled, it will be converted from a Cassegrain configuration to Newtonian. For astronomy aficionados, this means the telescope will provide a more versatile, f/4.9 focal ratio than the current and excessively long f/14.5 ratio. The new focal ratio is what will allow the telescope to be used effectively for astrophotography.

Another key upgrade will take place after the telescope is reinstalled. Within the next six months, the primary mirror assembly will be removed to allow for installation of a new primary mirror that will comprise cellular optics to research-specifications. The new mirror will be less than 2 inches thick and will weigh 35 pounds, as opposed to the current mirror, which is 5 inches thick and weighs more than 200 pounds. This upgrade will dramatically improve the telescope's resolution and enable it to reach thermal equilibrium in 15 minutes, rather than the 4 hours it currently takes to cool to ambient temperature.

This upgrade is part of a multi-phase capital project taking place at the park. The project scope includes a new sidewalk, deck and solar telescope. Next year, State Parks will replace the existing interpretive center structure, except for the dome.

The upgrade marks the first large-scale service and maintenance the telescope has undergone since it was installed at the park in 1973. The old mirror will be put on display to honor the founders who constructed it.

About Goldendale Observatory State Park Heritage Site

The five-acre day-use park is located two miles north of the town of Goldendale and is a certified Dark Sky Park. For more information about the park, visit: In addition, the Friends of Goldendale Observatory group provides weather information, local news, show times and information about how people can join and support the park at 


About Washington State Parks

The Washington State Parks and Recreation Commission manages more than 100 state parks and properties totaling approximately 120,000 acres. The Commission provides a variety of recreation opportunities for citizens and provides stewardship protection for a diverse array of natural, cultural and historic resources. State Parks’ statewide programs include long-distance trails, boating safety and winter recreation.

Follow Washington State Parks:

Share your favorite state park adventure on the State Parks’ blog site at

Support state parks by purchasing your annual Discover Pass today, and enjoy a whole year of outdoor fun on Washington’s beautiful state-managed recreation lands. For more information, visit

MEDIA CONTACTS:                         

Toni Droscher (360) 902-8604
Troy Carpenter, (509) 773-3141

Wash. Telecommunications Relay Service: (800) 833-6388




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