This is a model of the 200″ Hale Reflector Telescope at the Mount Palomar Observatory in San Diego Country, California. It sits on a rectangular plywood base, painted grey, with grey supports at the narrower ends. One of these supports is lower, and supports the base of the telescope model. The other consists of two taller stands with a bar connecting the two; this holds the top of the telescope.
The telescope is cagelike, with two solid cylindrical sections on either side, connected at the lower base with a broad bar; this represents the equatorial mount, which can be rotated as a whole, representing the right ascension of the telescope. The telescope can be tilted within the mount, representing the declination of the telescope.
At the base of the telescope, there is a green disk; this represents the telescope’s 5m mirror. At the top end is another green section, where a long cylindrical piece is supported by wires in the centre of the telescope; this represents the prime focus cage and the central section which contains the Goude and Cassegraine mirrors.
Accession Number: 2014.ast.31
Alternative Name: Mount Palomar Observatory Telescope
Primary Materials: Wood, Metal: Iron Alloy
On stickers affixed to the base of the mode: “200-IN REFLECTOR MOUNT PALOMAR OBSERVATORY.”
“University of Toronto – ASTRONOMY – David Dunlop Observatory.”
Base: Height=1.5cm, Width=30.5cm, Length=48cm. Telescope: Height= 78cm (when in untilted position).
This telescope was built at the David Dunlap Observatory as part of a set of educational models of large telescopes, designed to show how different telescopes could be adjusted and used.
Fair: The wood and paint of the model is in good condition, although worn and chipped in paces. The model still rotates well. The prime focus cage portion of the model is held together by wires and screws: these are pulling away from each other, and this portion of the model is very delicate and in poor condition.
Associated Instruments: 2014.ast.23
The Workshop at the David Dunlap Observatory, Richmond Hill
Date of Manufacture: 1952-1953
This model, with three others, was constructed at the David Dunlap Observatory in Richmond Hill in or just before 1953. It was kept there until the University of Toronto sold the Observatory in 2009, at which point it was moved to the Department of Astronomy & Astrophysics U of T’s St George Campus along with other objects from the Observatory. In 2017, the model was moved to another storage location in the McLennan Physics Building.
Description of <a href=”http://www.astro.caltech.edu/palomar/about/telescopes/hale.html”>The 200-inch (5.1-meter) Hale Telescope</a> from the Palomar University.
This model, and the others like it, are described in the Dunlap Observatory’s 1953 update in the Notes from Observatories in the Journal of the Journal of the Royal Astronomical Society of Canada, Vol. 47, p.96: “A number of demonstration models depicting the largest telescopes in present use have been constructed in the shop of the David Dunlap Observatory. Built to the scale of one-quarter inch to the foot, these moving models were intended to demonstrate the advantages and drawbacks of the various methods of mounting an astronomical telescope. While primarily intended for the classroom, the models were displayed at the recent At-Home of the Royal Astronomical Society of Canada and at the Canadian Hobby and Homecraft show where they were viewed with lively interest. The limitations of a telescope mount or its ease of handling can be graphically demonstrated with models in a manner not possible with only diagrams and explanations.”
Professor Emeritus John Percy remembers them being useful later in the 20th century in the teaching of undergraduate students, particularly with regards to the operation of the David Dunlap Observatory’s 74” telescope itself:
“[B]ecause they were a more or less exact model they didn’t convey any misconceptions, and they gave you a way of visualizing how the telescope moved, how it could be pointed at different parts of the sky. You could certainly illustrate where the Newtonian focus was, and how difficult it was for Helen Hogg to access that [on the 74” telescope]. Whereas all the [other scientists] using it could conveniently [work] at floor level and so forth… And all three of the telescopes have a slightly different design for the mounting of it, to show there were different designs you could use and why you couldn’t use the same one for the 24-inch telescope, but you could for the 74-inch telescope.”
The models were mostly used on the downtown campus, where undergraduate classes were held.
John Percy was interviewed on March 11, 2021.