In collaboration with the
International Astronomical Union


Category of Astronomical Heritage: tangible immovable
Ole Rømer Observatory, Denmark

Format: IAU - Outstanding Astronomical Heritage Description

Description

Geographical position 
  • InfoTheme: Astronomy from the Renaissance to the mid-twentieth century
    Entity: 139
    Subentity: 1
    Version: 4
    Status: PUB
    Date: 2021-03-14 18:43:46
    Author(s): Gudrun Wolfschmidt

Ole Rømer’s Observatorium Tusculanum,
Kroppedals Allé 3, 2630 Taastrup

 

Location 
  • InfoTheme: Astronomy from the Renaissance to the mid-twentieth century
    Entity: 139
    Subentity: 1
    Version: 3
    Status: PUB
    Date: 2019-06-17 17:03:51
    Author(s): Gudrun Wolfschmidt

Lat. 55° 41′ 06″ N, long. 12° 18′ 42″ E, elevation 32m above mean sea level.

 

 

IAU observatory code 
  • InfoTheme: Astronomy from the Renaissance to the mid-twentieth century
    Entity: 139
    Subentity: 1
    Version: 3
    Status: PUB
    Date: 2021-03-14 16:57:06
    Author(s): Gudrun Wolfschmidt

no IAU code

[not to be mistaken for IAU 155 Ole Rømer Observatory, Aarhus, Midtjylland, Denmark]

 

Description of (scientific/cultural/natural) heritage 
  • InfoTheme: Astronomy from the Renaissance to the mid-twentieth century
    Entity: 139
    Subentity: 1
    Version: 3
    Status: PUB
    Date: 2021-03-14 18:44:35
    Author(s): Gudrun Wolfschmidt

The first Meridian Circle, called the <i>Rot

Fig. 1. The first Meridian Circle, called the Rota Meridiana, constructed by Rømer in 1704 at his Countryside Observatory Tusculum in Taastrup near Copenhagen (Horrebow, Peder: Basis Astronomiæ 1735)



Ole Christensen Rømer (1644--1710) is known for his spectacular discovery, that the speed of light is finite, which he measured with astonishing precision -- by observing the Jupiter moons.
Already Galilei had proposed a method, based on the times of the eclipses of the four moons of Jupiter, using the Jovian system as a cosmic clock in order to solve the  longitude problem.



But Rømer is also a talented instrument maker -- the highlight is the invention of the meridian circle, called the Rota Meridiana, in 1704 at this site Tusculum. By observing the angle of a celestial body above the horizon, one gets its altitude; the altitude is largest when the celestial body crosses the meridian line - and this is connected to the time.

He was also a very careful observer, who discussed instrumental errors long before this was normal like in the 19th century. Especially, Rømer derived a measurement error formula for his meridian instrument in his Adversaria (1705). Today this measurement error formula is attributed to Tobias Mayer (1723--1762), who found it 51 years later, i.e. in 1756, without knowing Rømer’s derivation.

 

History 
  • InfoTheme: Astronomy from the Renaissance to the mid-twentieth century
    Entity: 139
    Subentity: 1
    Version: 3
    Status: PUB
    Date: 2021-03-14 18:45:20
    Author(s): Gudrun Wolfschmidt

Ole Rømer (1644--1710), painting by Jacob Coning

Fig. 2. Ole Rømer (1644--1710), painting by Jacob Coning (1700), Frederiksborg Museum (Wikipedia)



Ole Christensen Rømer (1644--1710) studied astronomy in Copenhagen, 1662--1671. Jean Picard (1620--1682) invited him to Paris, where he worked from 1672 to 1681 (micrometer 1572, mechanical models for planetary orbits, including a Jovilabium, 1677, a Lunarium 1680).

Rømer is best known is his proof (1676) based on the observation of the Jupiter moons that the speed of light is finite -- and not infinitely large. As a professor of mathematics in Copenhagen from 1681 he unified weights and measures.

Ole Rømer, observing with a meridian cicle, model

Fig. 3. Ole Rømer, observing with a meridian cicle, model in the Deutsches Museum in Munich (photo: Gudrun Wolfschmidt)



His most important instrumental achievement was the development of the meridian circle (1700), an innovative accurate measuring instrument for star positions.
Since Tycho and especially in the 17th and 18th century, large mural quadrants were used, made by the London instruments like William Cary (1759--1825), John Cary (1791--1816), John Bird (1709--1776) or Jesse Ramsden (1735--1800).

Repetition circle (1752) of Tobias Mayer (1723--17

Fig. 4. Repetition circle (1752) of Tobias Mayer (1723--1762) (Benzenberg, 1812)



The next step in the development was the repeating circle, invented by Tobias Mayer (1723--1762) -- starting his work in 1750, inspired by the transit instrument (1690) and the alt-azimuth (1704) of Ole Rømer. Mayer published his invention as Nova methodus perficiendi instrumenta geometrica et novum
instrumentum goniometricum
in "Commentaria Societatis Goettingensis" II (Göttingen 1752); later published by Benzenberg (1812). Mayer’s repetition circle could be used for surveying, but especially for the longitude problem for navigation. Inspired by Tobias Mayer the instrument makers Borda (1775) and Lenoir (1805) developed repeating circles.

200 years after Rømer -- Johann Georg Repsold (1770--1830)  opened a workshop in Hamburg in 1799, and developed the first modern meridian circle (1802). A little bit later, Stephen Groombridge (1755--1832) constructed his transit circle (1806). Thus in the 19th century, the meridian circle and the transit instrument became standard eqipment of observatories.

Rømer’s Observatory Tusculum (Kroppedal Mus

Fig. 5. Rømer’s Observatory Tusculum (Kroppedal Museum Taastrup)



Rømer used his Countryside Observatory Tusculum (in Taastrup) from 1704 until 1716. Some instruments were moved to Rundetårn in Copenhagen, others can be seen in the Kroppedal Museum near Copenhagen (opened in 1979). There an exhibition with collections on Ole Rømer is shown. Rømer wanted to measure the parallax precisely in order to prove Copernicus’ (1473--1543) heliocentric world view.

 

 

State of preservation 
  • InfoTheme: Astronomy from the Renaissance to the mid-twentieth century
    Entity: 139
    Subentity: 1
    Version: 2
    Status: PUB
    Date: 2018-08-23 14:45:34
    Author(s): Gudrun Wolfschmidt

There is not much left from the observatory, but the pillars of the meridian circle.

 

 

Comparison with related/similar sites 
  • InfoTheme: Astronomy from the Renaissance to the mid-twentieth century
    Entity: 139
    Subentity: 1
    Version: 3
    Status: PUB
    Date: 2021-03-14 18:46:15
    Author(s): Gudrun Wolfschmidt

Cf. like the meridian pillars of the Seeberg Observatory in Gotha.

 

 

Threats or potential threats 
  • InfoTheme: Astronomy from the Renaissance to the mid-twentieth century
    Entity: 139
    Subentity: 1
    Version: 2
    Status: PUB
    Date: 2021-03-14 18:46:39
    Author(s): Gudrun Wolfschmidt

Meridian pillars protected in the Kroppedal Museum Taastrup

 

Present use 
  • InfoTheme: Astronomy from the Renaissance to the mid-twentieth century
    Entity: 139
    Subentity: 1
    Version: 2
    Status: PUB
    Date: 2018-08-23 14:47:53
    Author(s): Gudrun Wolfschmidt

Kroppedal Museum Taastrup

 

 

Astronomical relevance today 
  • InfoTheme: Astronomy from the Renaissance to the mid-twentieth century
    Entity: 139
    Subentity: 1
    Version: 2
    Status: PUB
    Date: 2021-03-14 18:47:13
    Author(s): Gudrun Wolfschmidt

no astronomical relevance, but for history of astronomy an important step in the development of the meridian circle.

 

References

Bibliography (books and published articles) 
  • InfoTheme: Astronomy from the Renaissance to the mid-twentieth century
    Entity: 139
    Subentity: 1
    Version: 4
    Status: PUB
    Date: 2021-03-14 18:47:50
    Author(s): Gudrun Wolfschmidt


  • Benzenberg, Johann Friedrich (ed.): Erstlinge von Tobias Mayer. Düsseldorf 1812.

  • Herbst, Klaus-Dieter: Die Entwicklung des Meridiankreises 1700--1850. [The development of the meridian circle 1700--1850] Genesis eines astronomischen Hauptinstrumentes unter Berücksichtigung des Wechselverhältnisses zwischen Astronomie, Astro-Technik und Technik. Bassum, Stuttgart: GNT 1996.

  • Horrebow, Peder: Basis astronomiae sive astronomiae pars mechanica [...]. Havniae [Copenhagen]: apud D viduam beati Hieron. Christiani Paulli 1735.

  • Nielsen, Axel V.: Ole Rømer and his Meridian Circle. In: Vistas in Astronomy 10 (1968), p. 105-112.

  • Wolfschmidt, Gudrun: Mondtopographie und Längengrad. In: Tobias-Mayer-Symposium anläßlich des 250. Todestages von Tobias Mayer. Hg. von Erhard Anthes und Armin Hüttermann. Leipzig: AVA - Akademische Verlagsanstalt (Acta Historica Astronomiae, Band 48) 2013, S. 161-210.

 

 

Links to external sites 
  • InfoTheme: Astronomy from the Renaissance to the mid-twentieth century
    Entity: 139
    Subentity: 1
    Version: 5
    Status: PUB
    Date: 2021-03-14 18:48:30
    Author(s): Gudrun Wolfschmidt


  • Biography of Ole Rømer (1644--1710).
    In: The Abraham Zelmanov Journal 1 (2008), p. I-VI.
    http://zelmanov.ptep-online.com/papers/zj-2008-b1.pdf

  • Dystrup, Allan: Cloudy Nights, Classic Astronomy History,
    https://www.cloudynights.com/topic/585769-classic-astronomy-history/

  • Ole Roemer -- A key figure in the history of optics
    https://www.college-optometrists.org/the-college/museum/online-exhibitions/virtual-observatory-gallery/ole-roemer.html

  • Kroppedal Museum Taastrup
    http://kroppedal.dk/undervisning/undervisningsforloeb/astronomi/ole-roemer-mellem-himmel-og-jord/

 

 

 

 

  • PrintPrint contents of 'Description' tab
    (opens in a new window)
  • Theme

    Astronomy from the Renaissance to the mid-twentieth century

    Case Study Navigation