A 125-year-old Victorian era 18-inch (46-cm) aperture Brashear refracting telescope, with an illustrious history that has languished in storage for half a century, has found a new home in New Zealand. This marks the first step on the road to restoring the instrument to its former glory, destined to become the centrepiece of a public outreach Astronomy Centre near the shore of Lake Tekapo in the heart of New Zealand’s South Island.
John Brashear (1840-1920), a renowned Pennsylvanian optician and instrument maker, made some highly sought after telescope lenses — the largest being the 30‐inch refractor of the Allegheny Observatory in Pennsylvania. Brashear completed the 18‐inch (45‐cm) diameter, 8‐metre focal length ‘achromatic doublet’ in the early 1890s. Several subsequent observers attest to the exceptional quality of the 18-inch lens.
John Brashear (1840-1920), a renowned Pennsylvanian optician and instrument maker, made some highly sought after telescope lenses — the largest being the 30‐inch refractor of the Allegheny Observatory in Pennsylvania. Brashear completed the 18‐inch (45‐cm) diameter, 8‐metre focal length achromatic doublet in the early 1890s. Several subsequent observers attest to the exceptional quality of the 18-inch lens.
A brief history
The 46-cm diameter, 8-metre focal length achromatic doublet lens of the great refractor was made by renowned Pennsylvanian optician John Brashear (1840-1920) in the early 1890s. It was the primary instrument used by Percival Lowell for his Mars studies in 1894 at the Lowell Observatory in Arizona, until it was replaced by the 24-inch (61-cm) Alvan Clark refractor.
In 1895‐96, the 46-cm Brashear lens was fitted in a new 8-metre-long tube atop a 5.4-metre-high German equatorial mount and pier fabricated by the illustrious Warner & Swasay Co. of Cleveland, Ohio (the same company that built the 36‐inch Lick and 40‐inch Yerkes refractors) and installed in a 10‐metre diameter dome at the Flower Observatory, owned by the University of Pennsylvania. The complete instrument weighed in excess of 7 tons.
For over half a century, the 18‐inch Brashear refractor produced a wealth of valuable research data. Walter Leight, keen Mars observer and instrument maker at Flower Observatory, held the Brashear in high regard. He is documented as having used powers of 972x to observe planet Saturn stating, “We often saw things (like numerous subdivisions in Saturn’s rings) we weren’t supposed to see and we didn’t mention them.” Walter Haas (ALPO founder) is also on record as stating that the 18‐inch gave him the best views of Saturn he’d had in any telescope.
The 18-inch f/17 Brashear refractor in its late 19th century heyday at the Flower Observatory in Pennsylvania., mounted on a German equatorial fabricated by the illustrious Warner & Swasay Co. of Cleveland, Ohio. the same company that built the 36‐inch Lick and 40‐inch Yerkes refractors. Image credit: University of Pennsylvania.
The 18-inch f/17 Brashear refractor in its late 19th century heyday at the Flower Observatory in Pennsylvania, mounted on a German equatorial fabricated by the illustrious Warner & Swasay Co. of Cleveland, Ohio, the same company that built the 36‐inch Lick and 40‐inch Yerkes refractors.
The Flower Observatory was closed in 1954 and amalgamated with the nearby Cook Observatory that was acquired by the University of Pennsylvania. It was about this time that the 18‐inch Brashear was dismantled and placed into storage. In 1962, the university was looking to establish a Southern Hemisphere station and entered into partnership with the University of Canterbury at Christchurch in New Zealand. One of the fruits of this academic union was the Mount John University Observatory on the western shore of Lake Tekapo.
The Brashear arrived at Mount John in October 1963, but funds were not forthcoming for the construction of a suitable dome and auxilliary buildings, so the instrument (sans optics) remainded in storage on the mountain until 1990 when it was transferred to the Yaldhurst Museum near Christchurch. Sadly, Yaldhurst was unable to raise enough money to build a home large enough for the assembled telescope, so it was consigned to an outbuilding for a further 25 years.
Based in Tekapo township in the South Island of New Zeland in the shadow of Mount John is the headquarters of Earth & Sky Ltd., an astrotourism venture that offers stargazing tours at its two public outreach observatories at Cowan’s Hill and atop Mount John amid the domes of the university research facilities. The Mackenzie District’s unusual microclimate ensures that the region is blessed with a high proportion of clear, exceptionally dark nights. The IDA recently declared the area an International Dark Sky Reserve, the largest in the world.
Earth & Sky is about to embark on the construction of an ambitious Astronomy Centre, the restored Brashear telescope forming the centrepiece of a working museum that will also feature a collection of displays about leading NZ astronomers and the site testing and history of Mount John.
Earth & Sky’s general manager Margaret Munro said that the Brashear was an amazing and beautiful piece of 19th-century technology. “Having this sort of equipment in the Southern Hemisphere is really rare. Once it’s restored it will be a big drawcard for the region and will be an important part of the theme we are creating in Tekapo around the night’s sky,” she added.
Munro said the big unknown was how much the telescope would cost to restore, but the plan was to time the restoration so it could be installed in the Astronomy Centre in time for its opening. Until such time as it goes on display, the Brashear has a temporary home at the spacious workshop of Mackenzie Electrical in the township of Fairlie, just 30 minutes drive east of Tekapo.
The 18‐inch Brashear telescope is one of a half dozen giant refractors known to exist in the entire Southern Hemisphere and one of just two dating from the 19th century.
[UK Astronomy Now].
Of note, other telescopes at the Mt. St. John observatories include:
- MOA Telescope. This telescope was built by Japanese astronomers and is dedicated to the MOA project. It is a 1.8m prime focus reflector. The MOA telescope is the largest telescope in New Zealand.
- McLellan Telescope.This is a 1.0m Dall-Kirkham reflecting telescope run at either f/7.7 or f/13.5. Photometric imaging is by CCD camera and spectroscopy is by fibre-optic cable to the HERCULES spectrograph.
- Boller & Chivens Telescope. This is a 0.61m reflecting telescope run at either f/13.5 or occasionally f/6.25. Photometry is usually carried out using an Apogee Alta CCD camera.
- Optical Craftsmen Telescope.This is a 0.61m fork mounted reflecting telescope operating at f/16. This telescope is used exclusively for CCD photometry. It is currently being upgraded and commissioned for robotic use as part of the AAVSO's Robotic Telescope Network.
- Earth and Sky Telescope. This telescope, used exclusively for visual tourist operations is a 0.4m Meade LX200 telescope.
Edited by chris charen, 05 December 2018 - 01:44 AM.