General Information

Serial #

N/A

Part Number

1

Total Parts

8

AKA

Engine, measuring

Patents

N/A

General Description

Metal casings, controls and parts/ Synthetic controls and parts/ Glass? optical elements

Dimensions

Note: These reflect the general size for storage and are not necessarily representative of the object's true dimensions.

Length

98.5 cm

Width

73.7 cm

Height

150.0 cm

Thickness

N/A

Weight

N/A

Diameter

N/A

Volume

N/A

Lexicon

Group

Astronomy

Category

Research

Sub-Category

N/A

Manufacturer

AKA

Perkin Elmer

Country

Unknown

State/Province

Unknown

City

Unknown

Context

Country

Canada

State/Province

Ontario

Period

1974+

Canada

An instrument used at the David Dunlap Observatory at the University of Toronto, one of Canada's most important astronomical observatories. The David Dunlap Observatory opened in 1935 as the result of a bequest from the wife of David Dunlap. The telescope was a 74 inch (188 cm) reflector built by Grubb Parsons of Newcastle-upon-Tyne in England. The 74 inch was then the largest telescope in Canada (surpassing the 72 inch telescope of the Dominion Astrophysical Observatory in Victoria) and became the second largest in the world after the 100 inch Hooker Telescope of the Mt. Wilson Observatory outside Los Angeles. DDO's reputation grew and following WWII, it began to graduate most of the astronomers produced in Canada with University of Western Ontario far behind. Beginning in the 1960s a number of other astronomy departments were created but UofT/DDO held its place, a position it probably still holds. The DDO had a good technical staff which gave them an advantage and, with most of the 1940s to early 1970s top astronomers coming from UofT, grants from NRC and then ENSERC were almost guaranteed and allowed UofT's top astronomers -- Hogg, van den Berg, Fernie, Bolton, Kamper, Martin, etc. to acquire or build some of the best equipment available in university observatories. For optical observatories, only the DAO had technical staff and budgets that surpassed those of DDO. In 2007, citing increasing light pollution, the University of Toronto announced plans to sell the Observatory property. In June 2008, it was sold to Corsica Development Inc., a subsidiary of Metrus Development Inc. and the Observatory was closed. In 2009 the Observatory buildings and 80% of the site were designated a cultural heritage landscape. Also in 2009 Corsica and the Royal Astronomical Society of Canada, Toronto Centre announced an agreement allowing the RASC to provide public education and outreach programs at the observatory, and to operate the 188 cm telescope.

Function

A device used for digitally measuring spectra on photographic plates in an astronomical observatory.

Technical

This Perkin-Elmer PDS machine is a device for digitally measuring photographs. When purchased in 1974 by Dr. Tom Bolton with NSERC funding to the tune of approximately $150,000 - a very significant purchase at the time and the only one in Canada. It was used to measure both stellar and galactic spectra as well as direct images of the sky taken with the DDOs 74 inch telescope and plates acquired by Sidney Van de Burgh at the 48 inch Mt. Palomar Schmidt telescope. Subsequently the Dominion Astrophysical Observatory in Victoria acquired another such instrument and it is still being used to scan the spectra in their historic spectroscopic plate collection dating back to 1917. The PDS was the first generation of digital scanning equipment (there had been analogue instruments in use from the 1920s or 1930s in Canada) which we take for granted today. However, the stability of the PDS is so good that the best scanners today can barely match it. Part of the decision on whether to donate the PDS to the Canada Museum of Science and Technology was based on test to confirm whether the new machines could do the job they require.

Area Notes

Unknown

Details

Markings

Blue, black and silver plate on scanner front reads 'PERKIN ELMER PDS Microdensitometer'; indented black lettering on lens casing reads 'Nikkon/ 35999/ MADE IN JAPAN';white lettering on lens reads 'NIKKON'; white lettering for control functions/ Partly inaccessible label on motor reads 'MICRO SWITCH FREEPORT, ILL. U.S.A.'/ Silver lettering for control functions on control panel/ Plate on front of power supply reads 'FLUKE [logo] 12524' and black lettering reads '412B HIGH VOLTAGE POWER SUPPLY'/ White lettering on second interior unit reads 'SERVO CONTROLLER'

Missing

Unknown

Finish

Textured black painted scanner casing; glossy black painted lens housing with plated parts; black synthetic controls/ Glossy black painted and brushed metal parts/ Glossy black painted table top/ Glossy light grey painted control panel with glossy light grey painted surround; black. red, white and blue synthetic and plated metal controls and parts/ Glossy painted medium blue base casing/ Grey and black synthetic cable coverings

Decoration

N/A