After more than five years of redesign, engineering, and commissioning, the 18” handicap-accessible Wren-MarcarioAccessible Telescope (WMAT) will be rededicated at the McDonald Observatory Frank N. Bash Visitor’s Center this Saturday, July 17, 2010. The recommissioning of the telescope was completed by Las Cumbres Observatory Global Telescope Network (LCOGT) engineers and scientists, and funded by LCOGT founders Wayne Rosing and Dorothy Largay, Mike and Shirley Marcario, Mike I. and Dee Jones, Bill and Becky Wren and anonymous donors. The event marks the long-anticipated return of the science-grade telescope to a facility that receives over 60,000 visitors a year.
The George B. Wren II Supernovae Search Telescope (SNST) was originally dedicated in May of 1995 in memory of George B. Wren (1917-1993) who was the founder of Pipeline Inspection Company and made numerous advances in pipeline leak detection systems in his lifetime. George Wren built a scale model of the SNST shortly before his death. His son, astronomer William Wren, was looking for supernovae using 30" and 36" telescopes at the time. He found 1992H, 1994Y, 1997cq, and 1997ea using these scopes.
William Wren chose the unique Fundyscope design for the new telescope because it increased the search rate for visual identification of phenomena such as supernovae. Called Fundyscope after John Fundingsland who independently invented the design, another 'fund', August Pfund actually created the earliest example of this type. A Fundyscope consists of a paraboloid objective mirror, a prime focus eyepiece, and a flat control mirror. The McDonald telescope, the largest known implementation of a Fundyscope on the planet, deploys the mirrors and eyepiece on separate piers.
The telescope is being rededicated as the Wren-Marcario Accessible Telescope to honor both Wren and Michael Marcario (1954-1998). Marcario, through his company High Lonesome Optics, designed innovative and high-grade optical systems for telescopes and spectrographs. The scope incorporates a rigid mount, low diffraction optics, and a fixed viewing position. It contains two 18-inch, f/8 primary mirrors and a 24-inch diameter control mirror.
Wayne Rosing and several LCOGT engineers have been on-site completing final commissioning and upgrades for the telescope in the hours leading up to the dedication.
The dedication ceremony, to be attended by Rosing, LCOGTpersonnel, and officials from the University of Texas, Austin and their Astronomy Program, commences in daylight on the afternoon of the 17th. Festivities will spill into the night as the telescope is put to use in the dark skies above the Davis Mountains of Texas.
Human-Engineering Design
McDonald Observatory is the University of Texas at Austin’s Astronomy Department's facility. Situated in the darkest county in Texas, McDonald sits in the Davis Mountains 440 miles west of the University campus and 200 miles southeast of Juarez, Mexico. The telescopes on site range from the 9.2m Hobby-Eberly telescope to a 0.8m telescope and support a wide spectrum of astronomical studies. The WMAT fulfills the role of a publicly-available, eyepiece telescope on the popular site.
One impetus for the redesign and rededication of this telescope has been the demand for telescope access for mobility impaired or completely wheelchair bound individuals. The Observatory Visitor’s Center receives 60,000 visitors a year, many for the Observatory’s popular Star Parties. The redesigned telescope and viewing area ensures that nearly everyone who visits will be able to observe astronomical targets.
The revised design includes two 18” (0.46m) primary mirrors aligned north-south with a steering flat mirror centered between them to allow easier, quicker access to the entire sky. When the flat steering mirror is pointed towards the south with the observer to the north, the observer can see the southern sky quadrant. The northern quadrant becomes visible by rotating the flat mirror and eyepiece assembly 180º. This movable flat mirror allows the telescope to slew quickly to numerous targets in rapid succession while the eyepiece remains fixed.
After an extensive tear-down, redesign, and rebuild conducted at LCOGT’s Goleta, California headquarters, LCOGT engineers began on-site mechanical assembly of the WMAT in late June of 2009. LCOGT software engineers arrived the following week to begin the process of installing and refining the operational controls.
Working on the telescope during one of the Observatory’s monthly Star Parties, the LCOGT engineering crew decided to test the “DeathStar” manual pointing procedure using an extremely bright hand-held laser. The effect in the dark of night is captivating and soon the entire 300-participant Star Party had encircled the new telescope.
In less than a minute, visitors had formed a line to look through the telescope. First astronomical light for the public was obtained by a 10-year old boy who personally pointed the telescope at the Moon. As a direct result of accidentally working the Star Party that night, LCOGT engineers generated numerous telescope improvements, with particular emphasis on how people may better interact/interface with theinstrument.
Images seen through the WMAT are remarkably clear, crisp, and detailed. The unique optical design of the instrument, prime focus viewing with only two reflections and no central obstructions, makes for one of the best instruments available for public viewing of astronomical targets.
Commissioning of the WMAT telescope began in July, 2009, following hardware and optics installation. A Telescope Control System (TCS)computer allows the instrument to target and track objects quickly over the entire sky. The telescope performed flawlessly throughout Spring Break, 2010, with stunning views available for over 3,000 visitors.
