Leiden Observatory () is an astronomical institute of Leiden University, in the Netherlands. Established in 1633 to house the quadrant of Willebrord Snellius, it is the oldest operating university observatory in the world, with the only older still existing observatory being the Vatican Observatory. It is not known whether Golius had any instrumentation other than Snellius' quadrant at the observatory.

In 1682 Burchardus de Volder became professor of mathematics at the university and thus took over responsibility for the observatory. During his tenure, the observatory was enlarged, including a second turret to house a brass sextant which he purchased, and the rebuilding of the old turret. Both turrets had rotating roofs. Upon retiring in 1705, de Volder handed over a catalogue of instruments which showed that the observatory owned two other quadrants, a 12-inch telescope, two objectives, and several smaller telescopes. For the next two years, Lotharius Zumbach de Coesfeld ran the observatory until his appointment as professor of mathematics in Kassel in 1708. Between then and 1717 the observatory went without a director until Willem 's Gravesande was appointed director. During his time at the observatory, Gravesande purchased a number of new instruments including new telescopes and tools, before his death in 1742.

1860–1974

thumb|The second building to house the Leiden Observatory (built in 1860). This building now houses part of the law faculty. Two of the optical [[telescope domes can be seen on the roof.]]

By 1860 the new observatory building was completed. The new building was constructed in a quiet side of the city inside the university's botanical gardens. It consisted of a number of offices, living quarters for astronomers, and a number of observing domes containing telescopes. In 1873 two new rooms were added to the building in order to house the tools required to verify nautical instruments; tools used to test compasses, sextants and other instruments. Two of the domes were rebuilt, one in 1875 and the other in 1889. The collaboration lasted until 1972.

The building is now called the Oude Sterrewacht (Old Observatory). It was restored from 2008 to 2012, and in the 2010s houses a visitor center and also has tours.

1974-present

The astronomy department moved to the science campus north-west of the city centre in 1974. Although professional astronomical observations are no longer carried out from Leiden itself, the department still calls itself Leiden Observatory. In much of astronomy, the data came from elsewhere and could be analyzed and studied on the campus; for example in modern times the instruments may even be located in space, with data transmitted back to Earth and then studied on a computer display. (An example of this was the Astronomical Netherlands Satellite, launched in 1974.)

The archive of the Leiden Observatory is available at Leiden University Library and digitally accessible through Digital Collections

Einstein's Chair in the Ten-inch dome

thumb|Einstein's Chair

Einstein's Chair is an astronomical observing chair at the Leiden Observatory. This chair, made in 1861, is the only piece of furniture in the observatory that dates from that time. The chair gets its name from the fact that it was used by Albert Einstein on several occasions during his visits to the observatory. Einstein was a frequent visitor of the building during his professorship at Leiden University due to his good friendship with the director, Willem de Sitter. The chair can be found in the largest dome of the observatory, the so-called 10-inch dome (named after the 10-inch telescope that is placed inside). The chair is still used by observers and a popular attraction at the observatory.

On 21 October 2015, Einstein's Chair got a short segment on the Dutch astronomy program Heel Nederland Kijkt Sterren. During this segment the science populariser Govert Schilling and the science historian David Baneke talked about its origins.

Einstein is noted for his visits to Leiden Observatory during World War I.

Restoration

The old Observatory building facilities (from 1860s) was restored in the 2010s. While not longer the base for the modern Leiden Observatory academically, it does have the astronomical historical items at the facility. Also, a solar telescope was crowd funded to provide live optically transmitted images of the Sun to the Visitor center, which is also known to have offered tours.

Archive

The archives of the Leiden Observatory and its successive directors, 1829-1992 are held at Leiden University Libraries and are digitally available.

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File:Leiden Observatory in 1861 NW.png|Leiden Observatory in 1861 from the north-west direction.

File:ErfgoedLeiden LEI001016349 Panorama vanaf de Sterrenwacht.jpg|Panoramic view of Leiden from the Observatory. Glass negative, ca. 1900

File:NIMH - 2011 - 0300 - Aerial photograph of Leiden, The Netherlands - 1920 - 1940.jpg|Observatory and Hortus botanicus, ca. 1920–1940

Image:LeidenOldObservatory2010.jpg|The second building to house the Leiden Observatory, during restoration (2010).

Image:Leiden-Sterrewacht-2013-a.jpg|2013, after restoration.

Image:Huygens and Oort Buildings.JPG|The Huygens Laboratory (left) and J.H. Oort Building (right) which currently house Leiden Observatory on the 4th, 5th and 11th floors.

</gallery>

Directors

{| class="wikitable" style="text-align:center; width:30%"

!Term

!Director

|-

|1633–1667

|H. G. van de Sande Bakhuyzen

|-

|1908–1918

|E. F. van de Sande Bakhuyzen

|-

|1918–1934

|Ejnar Hertzsprung

|-

|1945–1970

|George K. Miley

|-

| 2004–2012

|Tim de Zeeuw

|-

|2012–2022

|Huub Röttgering

|-

| 2022–present

|Ignas Snellen

|}

Instruments

thumb|The Zunderman reflector

Examples:

  • Zes-Duims Merz Refractor (ch objective with wooden telescope tube dating to 1830s)
  • Ten-inch Repsold Refractor ( ch Alvin and Clark objective lens on Repsold und Söhne, since 1885)
  • Photographic Double Refractor (since 1897)
  • Zunderman Reflector (46&nbsp;cm diameter mirror (~18.1 inches), since 1947)
  • Heliostat

See also

  • Timeline of telescopes, observatories, and observing technology
  • List of largest optical telescopes in the 19th century

References

Further reading

  • Telescopes from Leiden Observatory and other collections. 1656 - 1859 (.pdf)
  • From attics to domes: Four centuries of history of Leiden Observatory
  • Leiden Observatory web site
  • History of Leiden Observatory (in Dutch)
  • Leiden Observatory Papers Archives of the Leiden Observatory and its successive directors, 1829-1992 Leiden University Libraries
  • The old observatory on GoogleMaps
  • The current observatory on GoogleMaps