Editing David Dunlap Observatory (section)

===Operations===
[[File:David Dunlap Observatory 1935.jpg|thumb|The view of David Dunlap Observatory in 1935. Observatory House is visible in the upper left.]]
[[File:Dunlap Observatory Administration Building.jpg|thumb|The administration building, with two of the observatory's telescopes built on top. The building's third dome is just out of sight behind the trees on the left.]]
From 1946 to 1951 the observatory director was [[Frank Scott Hogg]], who was joined at the DDO by his wife [[Helen Sawyer Hogg]]. After her husband's death, Helen continued at the observatory, surveying globular clusters to gauge their distance, publishing a major catalog of variable stars in clusters.<ref>{{cite journal |last=Hogg |first=Helen Sawyer |url=http://lepus.astro.utoronto.ca/AALibrary/pubs/DDOpubv3n6.pdf |title=A Third Catalog of Variable Stars in Globular Clusters Comprising 2199 Entries |year=1973 |journal=Publications of the David Dunlap Observatory |access-date=12 February 2015 |archive-date=3 March 2016 |archive-url=https://web.archive.org/web/20160303221340/http://lepus.astro.utoronto.ca/AALibrary/pubs/DDOpubv3n6.pdf |url-status=dead }}</ref> Her weekly 'With the Stars' column in the [[Toronto Star]] was published from 1951 to 1981. In 1959 and 1966 staff astronomer [[Sidney van den Bergh]] composed a database of dwarf galaxies known as the [[David Dunlap Observatory Catalogue]].<ref>{{cite journal |last=van den Bergh |first= Sidney |bibcode=1959PDDO....2..147V |title= A catalogue of dwarf galaxies |journal=Publications of the David Dunlap Observatory |volume= 2 |issue= 5 |year=1959 |pages= 147–150}}</ref>

In collaboration with the [[University of Toronto Faculty of Applied Science and Engineering|Department of Electrical Engineering]], [[Donald MacRae (astronomer)|Donald MacRae]] established a radio astronomy observatory on the observatory grounds in 1956.{{sfn|Fernie|2000}} The DDO work led to the 1963 measurement of the absolute [[flux density]] of [[Cassiopeia A]] at 320&nbsp;MHz, a radiometric standard. The DDO also built an {{Convert|18|m|ft|adj=on}} [[radio telescope]] in [[Algonquin Park]] in northern Ontario, co-locating it at the site of the larger [[Algonquin Radio Observatory]]. This instrument was actively used until 1991, when budget cuts led to it being abandoned. It was later used by a private group as part of a [[SETI]] project, [[Project TARGET]],<ref>{{cite web |url=http://www.setileague.org/general/history.htm |website= SETI League |title=A Brief SETI Chronology}}</ref> and has reported moved to a site outside [[Shelburne, Ontario]].

In 1960 observatory operations formed the narrative framework of the [[National Film Board]] (NFB) short film ''[[Universe (1960 film)|Universe]]''. The film was nominated for the [[33rd Academy Awards]] in the category of best documentary, short subject in 1961. ''Universe'' was shown at the [[1964 New York World's Fair]] where it was seen by [[Stanley Kubrick]] and [[Arthur C. Clarke]], who were starting work on the film that eventually became ''[[2001: A Space Odyssey (film)|2001: A Space Odyssey]]''. ''Universe'' featured future DDO director Donald MacRae and was narrated by Stanley Jackson.<ref>{{cite web |url=http://www.nfb.ca/collection/films/fiche/?id=10842 |title=Universe |website=National Film Board |archiveurl=https://web.archive.org/web/20170730010126/http://onf-nfb.gc.ca/en/our-collection/?idfilm=10842|archivedate=2017-07-30}}</ref>{{sfn|Seaquist|2006}}

[[Tom Bolton (astronomer)|Tom Bolton]] was hired as a postdoctoral fellow at the DDO in 1970. In 1971 he used data from the [[Uhuru (satellite)|Uhuru]] [[X-ray astronomy|X-ray observatory]], and [[Naval Research Laboratory]] [[sounding rocket]]s launched from [[White Sands Missile Range]]<ref>personal communication with Professor Bolton, 28 November 2007</ref> to find the optical [[Binary star|companion star]] to the X-ray source Cygnus X-1. Those X-ray telescopes had a certain degree of accuracy, but follow-up optical-wavelength studies of possible companions were required to eliminate a shortlist of many stars in the same area of sky. Bolton observed the star HDE 226868 independently of the work by [[Betty Louise Turtle|Louise Webster]] and [[Paul Murdin]], at the [[Royal Greenwich Observatory]], who could not prove that star was Cygnus X-1's optical companion. The high dispersion of the {{convert|74|in|m|adj=on}} telescope's spectrograph, combined with the {{convert|74|in|m|adj=on}} aperture was adequate to prove the star was the source of the X-ray emissions and that its behaviour was inconsistent with a normal eclipsing star.<ref>{{cite journal
 | last=Bolton | first=C. T. | date=1972
 | title=Identification of Cygnus X-1 with HDE 226868
 | journal=Nature | volume=235 | issue=2 | pages=271–273
 | doi=10.1038/235271b0 | bibcode=1972Natur.235..271B| s2cid=4222070 }}</ref><ref>{{cite journal|first=Bruce |last=Rolston |url=http://news.utoronto.ca/bin/bulletin/nov10_97/art4.htm |title=The First Black Hole |journal=The Bulletin |publisher=University of Toronto |date=10 November 1997 |url-status=dead |archive-url=https://web.archive.org/web/20080502230214/http://news.utoronto.ca/bin/bulletin/nov10_97/art4.htm |archive-date=2 May 2008 }}</ref>