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{{Use dmy dates|date=September 2019}}
[[File:Sternwarte Berlin Schinkel.jpg|thumb|upright=1.25|1838 painting of the New Berlin Observatory (Linden Street), where the planet [[Neptune]] was discovered in 1846.]]
[[File:Berlin Markthalle II Lageplan.jpg|thumb|right|Location of the ''Neue Berliner Sternwarte'', Berlin Observatory from 1835 to 1913]]
[[File:Berliner Sternwarte Babelsberg.jpg|thumb|By 1913, activities were moved to a new Observatory at Babelsberg, shown here in 2006]]

The '''Berlin Observatory''' ('''Berliner Sternwarte''') is a German astronomical institution with a series of observatories and related organizations in and around the city of [[Berlin]] in [[Germany]], starting from the 18th century. It has its origins in 1700 when [[Gottfried Leibniz]] initiated the "Brandenburg Society of Science″ (''Sozietät der Wissenschaften'') which would later (1744) become the [[Prussian Academy of Sciences]] (''Preußische Akademie der Wissenschaften''). The Society had no observatory but nevertheless an astronomer, [[Gottfried Kirch]], who observed from a private observatory in Berlin. A first small observatory was furnished in 1711, financing itself by calendrical computations.

In 1825 [[Johann Franz Encke]] was appointed director by King [[Frederick William III of Prussia]]. With the support of [[Alexander von Humboldt]], Encke got the King to agree to the financing of a true observatory, but one condition was that the observatory be made accessible to the public two nights per week. The building was designed by the well-known architect [[Karl Friedrich Schinkel]], and began operating in 1835. It now bears the IAU observatory code 548.

Although the original observatory was built in the outskirts of the city, over the course of time the city expanded such that after two centuries the observatory was in the middle of other settlements which made making observations very difficult and a proposal to move the observatory was made. The observatory was [[#Berlin-Babelsberg Observatory|moved to Potsdam-Babelsberg]] in 1913 (IAU observatory code [[IAU code#536|536]]). Since 1992 it is managed by the [[Leibniz Institute for Astrophysics Potsdam|Leibniz Institute for Astrophysics Potsdam (AIP)]], although it has not been used for German astronomical observations since the 20th century.

In Berlin remain the [[Wilhelm Foerster Observatory]] (IAU code 544), the [[Archenhold Observatory|Archenhold Sternwarte]], Berlin-Treptow (Archenhold Observatory; IAU code 604), the [[Urania (Berlin)|Urania Sternwarte]] (Urania Observatory, IAU code 537), and the Bruno H. Bürgel Observatory.

==History==
In September 1699, the Reichstag decided to introduce an "improved calendar" to the Protestant German states without having to take on the [[Gregorian calendar|Gregorian Calendar]], introduced by [[Pope Gregory XIII]] in 1582. The 'improved calendar' was introduced the following year and resulted in 18 February 1700 being followed by 1 March. A patent for the calendar was granted to the planned Berlin Observatory by [[Prince-elector]] [[Frederick I of Prussia|Frederick III]] on 10 May 1700 and eight days later Gottfried Kirch was appointed to Director of the Observatory. On 11 July (his 43rd birthday) the Kurfürst signed a document formally founding an Academy and an Observatory in Berlin. Therefore, Berlin received an academy just like those already existing in London, Paris and Rome – the [[Prussian Academy of Sciences]] (originally German name: ″Kurfürstlich-Brandenburgische Societät der Wissenschaften″), based on the plans of Gottfried Wilhelm Leibniz. Leibniz became the first president of the Academy. The fees resulting from the calendar patent were the almost single financial basis of the institution for a long period. The society originally had no actual observatory of its own and Kirch carried out his observations at various private observatories including, from 1705, the private observatory of Geheimrat Bernhard Friedrich von Krosigk on the Wallstrasse, in [[Cölln]]. Kirch was assisted by his wife [[Maria Margarethe Kirch|Maria Margarethe]] and his son Christfried. Maria Margarethe discovered, among other things, the comet of 1702. In the meantime the Kurfürst had been raised in 1701 to the rank of King in Prussia. On 1 January 1710, the capital was expanded by uniting the previously independent towns of Dorotheenstadt, Friedrichstadt, Friedrichwerder, and Cölln and Berlin (the oldest ones).

===The Old Berlin Observatory===

[[File:Berliner Sternwarte mueller.jpg|thumb|The royal stables and the observatory, [[watercolor]] painting by [[Leopold Ludwig Müller]], 1824]]

The first Berlin Observatory was sited in the Dorotheenstadt quarter. The Marstall [[Unter den Linden]] had been erected from 1687 to 1688 according to the plans of the architect [[Johann Arnold Nering]], originally for 200 horses, and a second storey was added from 1695 to 1697 for the [[Akademie der Künste|Academie der Mahler-, Bildhauer- und Architectur-Kunst]], founded in 1696. From 1696 to 1700, [[Martin Grünberg]] extended the complex northwards for the new Societät der Wissenschaften, doubling the perimeter out to the Letzten Straße (later: Dorotheenstraße)<ref>[http://luise-berlin.de/Lexikon/Mitte/d/Dorotheenstrasse.htm Dorotheenstraße] im Bezirkslexikon des [[Luisenstädtischer Bildungsverein|Luisenstädtischen Bildungsvereins]]</ref>).<ref>[http://www.luise-berlin.de/Lexikon/Mitte/a/Akademie_der_Wissenschaften.htm Akademie der Wissenschaften] im Bezirkslexikon des [[Luisenstädtischer Bildungsverein|Luisenstädtischen Bildungsvereins]]</ref> From 1700 until 1711, the observatory, a tower built by Grünberg with three levels, was added to the northern wing of the installation. The 27-meter-high building was one of the first tower observatories of the 18th century.<ref>{{cite web | url = http://www.pressestelle.tu-berlin.de/newsportal/vermischtes/2009/jahr_der_astronomie/ |title=Die erste Sternwarte Berlins |author=Hans Christian Förster |publisher=TUB-newsportal |date=9 February 2009 |access-date=24 November 2009}}</ref> The observatory became partly usable in 1706 and by 1709 was more or less completed.<ref name="Mommertz">[http://edoc.bbaw.de/oa/series/reXaIF2DOtIqw/PDF/27DPYkT1uhgo_201.pdf Monika Mommertz: Schattenökonomie der Wissenschaft]{{dead link|date=October 2016 |bot=InternetArchiveBot |fix-attempted=yes }} (PDF)</ref> On 15 January 1711 the ″Königlich Preußische Sozietät der Wissenschaften″ held its first meeting in the tower and four days later its first formal gathering, at which the observatory was officially handed over.<ref>[http://www.gerd-albrecht.de/Geschichte/Berlin%20im%20Jahr%201700-1799.htm Berliner Geschichte von 1700 bis 1799]{{dead link|date=October 2016 |bot=InternetArchiveBot |fix-attempted=yes }} bei gerd-albrecht.de</ref> It became an important focus of the Society. In time, its library and natural history collection also came to be housed under the same roof.<ref name="Mommertz" /> The Society was reorganized by [[Frederick II the Great|Frederick II]] in 1744 as the ″Royal Academy of Sciences″ (″Königlichen Akademie der Wissenschaften″) and retained its base there until 1752.<ref name="telegraph">[http://www.optischertelegraph4.de/stationen/1/index.html optischertelegraph4.de: Station 1: Berlin-Mitte Alte Sternwarte]</ref>

[[Gottfried Kirch]] died in 1710, a year before the official opening of the Academy and the Observatory. His assistant [[Johann Heinrich Hoffmann]] moved up to replace him as the head of the observatory. After his death in 1716 [[Christfried Kirch]], the son of Gottfried Kirch, became his successor. He was aided in his work on the calendar by his mother [[Maria Margarethe Kirch]] and his sister, just like he and his mother once helped his father. His mother died in 1720. From 1720 until 1736 he was assisted with the practical activities by J. G. Schütz. After the death of Christfried Kirch he took on the post of director in 1740. For many years the calculations for the calendar were continued the most part by Christine Kirch; she was also responsible for the keeping of the accounts.<ref>Galerie des Universums: {{Cite web|url=http://www.galerie-universum.de/gu_2003/webseiten/pnn_04.htm |title=Thema 4. Die ersten Jahre der Sternwarte und die Leistungen der Astronomenfamilie Kirch |accessdate=13 January 2009 }}{{dead link|date=November 2016 |bot=InternetArchiveBot |fix-attempted=yes }}</ref> During the years of "Old Observatory" questions of astronomy were also discussed and grappled with in Berlin by the likes of, among others, [[Leonhard Euler]], [[Joseph Louis Lagrange]] and [[Johann Heinrich Lambert]]. In 1765, [[Giovanni Salvemini|Giovanni_Salvemini (aka Johann Castillon)]] received the position of First Astronomer. In 1768, the Observatory received a [[Mural instrument|mural quadrant]] constructed by [[John Bird (astronomer)|John Bird]], their first really important observing instrument. This device can now be seen in [[Leibniz Institute for Astrophysics Potsdam|Babelsberg Observatory]].

[[Johann III Bernoulli]] served from 1764 to 1787 as Director of the Old Observatory and was succeeded by [[Johann Elert Bode]]. Lambert fetched Bode to Berlin in 1773, in order to publish an [[Nautical almanac|almanac]]; after Lambert' death, Bode became the sole editor.<ref>Galerie des Universums: {{Cite web|url=http://www.galerie-universum.de/gu_2003/webseiten/pnn_05.htm |title=Thema 5. Der Aufschwung der Wissenschaften unter Friedrich dem Großen (1712–1786) |accessdate=18 January 2009 }}{{dead link|date=November 2016 |bot=InternetArchiveBot |fix-attempted=yes }}</ref> The first edition of the ''[[Berliner Astronomisches Jahrbuch]]'' (for 1776) had already appeared by 1774, initiating the longest-lasting publication series in [[astronomy]], lasting until 1959. By virtue of this medium, Berlin Observatory developed into an information source of prime importance within Europe.<ref>{{Cite web | author = Wolfgang Kokott | url = http://www.astro.uni-bonn.de/~pbrosche/aa/acta/vol14/kokott.html | title = Bodes Astronomisches Jahrbuch als internationales Archivjournal | accessdate = 1 January 2009}}</ref> Originally Bode had the venerable Christine Kirch to assist him with the work on the calendar. In 1774, he married a granddaughter of one of her sisters; she was likewise entrusted with astronomical work in line with the Kirch family tradition.<ref>{{citation|surname1=Friedhelm Schwemin|editor-surname1=Wolfgang R. Dick|editor-surname2=[[Jürgen Hamel]]|title=Der Berliner Astronom : Leben und Werk von Johann Elert Bode (1747–1826)|edition=1.|volume=Acta Historica Astronomiae Vol. 30|publisher=[[Verlag Harri Deutsch]]|location=Frankfurt am Main|year=2006|pages=23 u. 136|isbn=3-8171-1796-5|language=German}}</ref> Christine Kirch died in 1782. As director of the observatory, Bode was able, through favors from [[Frederick William III of Prussia]], to extend the till then rather third-class-equipped institution with a second observing level. When Bode entered a petition to this effect on 2 November 1798, space for observing within the tower was still limited to the third storey. The two storeys over it were united to a single spacious level. From there, the observing activities could be extended, once the calculated cost of 4465 [[Prussian Thaler|Thaler]]s and the plan was approved on 7 April 1800 and the required conversion was completed by June 1801. The construction work was supervised by Oberhofbaurat and Schlossbaumeister Bock.<ref>{{citation|surname1=F. Schwemin|title=Der Berliner Astronom |page=51 |language=German}}</ref>

In 1797 [[Johann Georg von Soldner|Johann Georg Soldner]] arrived in Berlin as Bode's co-worker and in 1801 (″Astronomisches Jahrbuch für 1804″) Soldner's work appeared on the weight of light with implications for the curving of light rays in a gravitational field.<ref>Galerie des Universums: {{cite web|url=http://www.galerie-universum.de/gu_2003/webseiten/pnn_06.htm |title=Thema 6. Johann Georg Soldner und die Krümmung der Lichtstrahlen |access-date=20 January 2009 }}{{dead link|date=November 2016 |bot=InternetArchiveBot |fix-attempted=yes }}</ref> In 1805 [[Jabbo Oltmanns]] came to Berlin and assisted Bode with his astronomical observations and his work on the Jahrbuch, in which also the first of his own articles appeared. Oltmanns also became an assistant to [[Alexander von Humboldt]] and processed the positional data from his just completed research expedition through Mid- and South America; during this work, Humboldt was ordered to Paris on a diplomatic mission after [[Napoléon Bonaparte|Napoleon]]'s occupation of Berlin in 1806 and Oltmanns followed him in 1808. Until 1811, the astronomical institute financed itself almost exclusively from the monopoly on the calendar calculations, which had been conferred on the Academy at the time of its founding; in that year the Academy lost its calendar privileges and became dependent on the state budget and on charity.

[[File:Station-1-pruss-teleg.jpg|thumb|Tower of the old Berlin Observatory between 1832 and 1848, with signal mast of the optical telegraph. View from the west, by F.&nbsp;W.&nbsp;Klose]]

When the time came to seek a successor by virtue of Bode's retirement, both [[Carl Friedrich Gauß]] and [[Friedrich Wilhelm Bessel]] turned the post down.<ref>friedensblitz.de: {{cite web |url=http://www.friedensblitz.de/sterne/grossvaeter/encke.html |title=Johann Franz Encke |access-date=7 January 2009}}</ref> On the recommendation of Bessel, [[Johann Franz Encke]],<ref>knerger.de: {{cite web |url=http://www.knerger.de/html/enckejohwissenschaftler_53.html |title=Encke, Johann Franz |access-date=7 January 2009}}</ref> since 1822 Director of the [[Gotha Observatory|Seeberg Observatory]] near [[Gotha]], was called to Berlin by King Frederick William III in 1825 and named director of the Berlin Observatory. Thanks to the influence of Alexander von Humboldt, expensive instruments were obtained and with his aid Encke was also able to get the Prussian King to agree to the construction of a new observatory, situated on the edge of the city at that time. A condition was that the observatory should be made available to the [[public observatory|public]] on two evenings in the week.

The main instrument was a new [[refractor]] from the München (Munich) workshop of [[Joseph von Fraunhofer]] with an inner aperture of 9&nbsp;[[inch]]es (24.4&nbsp;cm) and an inner focal length of 4.33&nbsp;meters. Humboldt submitted a request for its purchase on 9 October 1828, including a [[meridian circle]] from the instrument maker of Berlin and a chronometer from the Berlin clockmaker. As a result, six days later, Frederick William III granted 8500 taler for the refractor, 3500 taler for the meridian circle and 600 taler for the chronometer. The refractor was the last great telescope from Fraunhofer, that was still available in München. At the same time, Humboldt received from the king the authority for the storage of associated documents in the Kultusministerium (cultural ministry) .<ref name="mh">{{citation|surname1=Kurt-R. Biermann|title=Miscellanea Humboldtiana |journal=Beiträge zur Alexander-Von-Humboldt-Forschung |publisher=Akademie-Verlag|location=Berlin|year=1990|pages=127–128|isbn=3-05-000791-5|issn=0232-1556|language=German|url={{Google books |plainurl=yes |id=2xkgcftaFagC |page=127 }}|access-date=4 December 2009}}</ref>

The Fraunhofer refractor arrived in Berlin on 3 March 1829.<ref>{{cite web |author=Berlin-Brandenburgische Akademie der Wissenschaften |url=http://www.bbaw.de/bbaw/Forschung/Forschungsprojekte/avh/de/Blanko.2004-12-14.3730549301 |title=Alexander von Humboldt Chronologie |access-date=21 November 2009 |quote=fraunhofer |url-status=dead |archiveurl=https://web.archive.org/web/20090829173837/http://www.bbaw.de/bbaw/Forschung/Forschungsprojekte/avh/de/Blanko.2004-12-14.3730549301 |archivedate=29 August 2009  }} – sehr lange Webseite</ref> Today it is in the [[Deutsches Museum]] in Munich.<ref>Deutsches Museum: [http://www.deutsches-museum.de/sammlungen/ausgewaehlte-objekte/meisterwerke-ii/refraktor/ Der Refraktor von Joseph von Fraunhofer] {{webarchive |url=https://web.archive.org/web/20131105054452/http://www.deutsches-museum.de/sammlungen/ausgewaehlte-objekte/meisterwerke-ii/refraktor/ |date=5 November 2013 }}</ref> On 7 April 1829, five days before the departure of Humboldt on his Russian expedition, he received a royal commission for the new observatory project planned by the architect [[Karl Friedrich Schinkel]] and its construction at the desired location. After his return, on 1 May 1830, Humboldt requested Schinkel by letter for a design.<ref name="mh" /> On 10 August 1830, the purchase of a building plot for the new observatory was authorized.<ref>{{Cite web |author= Luisenstädtischer Bildungsverein |author-link= Luisenstädtischer Bildungsverein |url= http://luise-berlin.de/kalender/jahr/1830.htm | title= Berlin im Jahr 1830 |accessdate=2 December 2009}}</ref>

The tower of the old observatory served as ''Telegraphenstation&nbsp;1'' between 1832 and 1849, one of the 62 stations of the [[Prussian semaphore system|Prussian optical telegraph]] from Berlin via [[Köln]] to [[Koblenz]].<ref name="telegraph" /> On 3 July 1903 the tower was torn down.<ref>{{citation|surname1=F. Schwemin |title=Der Berliner Astronom |pages=96|language=German}}</ref> The entire area of the Marstall complex between Dorotheenstraße and Unter den Linden was taken over in 1914 by the [[Berlin State Library]].

===New Berlin Observatory===

The construction of the new Berlin Observatory proceeded from a cabinet order of 10 November 1830 according to the design of Schinkel. An approximately one hectare plot was acquired at a price of 15,000 [[Thaler]]s in the present-day area of [[Berlin-Kreuzberg]]. The foundation stone was laid on 22 October 1832 and the observatory was ready by 1835, on the area currently bounded by the streets ″Friedrichstraße″, ″Besselstraße″ and ″Lindenstraße″. The southern end of the ″Charlottenstraße″ was later named ″Enckeplatz″ in honor of the director at that time and the observatory acquired the address of Enckeplatz&nbsp;3&nbsp;A (now: ″Enckestraße 11″).<ref name="luise a-sternwarte">[http://luise-berlin.de/lexikon/frkr/s/sternwarte_akademie_sternwarte.htm Akademie-Sternwarte] im Bezirkslexikon des [[Luisenstädtischer Bildungsverein|Luisenstädtischen Bildungsvereins]]</ref>

[[File:NHP 1879 Berlin Sternwarte Grundriss Tafel VIII.jpg|thumb|right|Plan of the new Berlin Observatory of 1879]]
[[File:NHP 1879 Berlin Sternwarte Nordseite Tafel VI.jpg|thumb|right|upright|The North Wing with the height datum of 1879]]

The two-storey building was a plastered building "in simple Hellenic style" as a link between the modern and antique. The building laid out in cruciform plan-form and extended to the east with its longest arm. At the meeting point of the arms of the cross a rotating iron dome was placed with a diameter of 7.5 metres. It was the first observatory dome in [[Prussia]] in the form of a hemisphere with a slit opening and rotation mechanism. The foundations of the actual observatory were separate from the other buildings, to avoid transmission of vibrations. Under the dome was the library. In the upper storey were further observational spaces as well as scientific work areas. The long east wing housed the living quarters of the director on the ground floor and was adorned with a temple front, which as the main frontage showed the God of Light [[Apollo]] with a [[quadriga]] in relief on the gables. To the east of the building stood a small house with the living quarters of the [[castellan]].<ref name="luise a-sternwarte" />

The observatory got a [[meridian circle]] from Karl Pistor.<ref>Galerie des Universums: {{cite web|url=http://www.galerie-universum.de/gu_2003/webseiten/pnn_07.htm |title=Thema 7. Der Bau der neuen Berliner Sternwarte und das Wirken von Johann Franz Encke und Alexander von Humboldt |access-date=14 January 2009 }}{{dead link|date=November 2016 |bot=InternetArchiveBot |fix-attempted=yes }}</ref>

On 24 April 1835 Encke could move into the new observatory, along with his newly appointed assistant [[Johann Gottfried Galle]]. On 19 May the first observations were carried out although the building was only fully finished at the end of 1835.<ref>{{cite web |author=Luisenstädtischer Bildungsverein |author-link=Luisenstädtischer Bildungsverein |url= http://luise-berlin.de/kalender/jahr/1835.htm |title=Berlin im Jahr 1835 |access-date=29 November 2009}}</ref> Galle had applied to become assistant to Encke a considerable time before the building became ready for occupancy.<ref>Galerie des Universums: [http://www.galerie-universum.de/gu_2003/ausstellungstafeln/ahnengalerie_wissenschaftler/galle_lang.htm Johann Gottfried Galle (1812–1910)] {{webarchive |url=https://web.archive.org/web/20040925173754/http://www.galerie-universum.de/gu_2003/ausstellungstafeln/ahnengalerie_wissenschaftler/galle_lang.htm |date=25 September 2004 }}</ref>

From May to August 1835 the Königsberg astronomer [[Friedrich Wilhelm Bessel]] carried out pendulum observations in the ″little magnetic house″ („Magnetisches Häuschen") in the grounds of the observatory (see Freydanck's painting on this page) for the creation of a new Prussian measurement of length.<ref>Astronomische Nachrichten 1920: {{cite journal |title=Friedrich Wilhelm Bessel |bibcode=1919AN....210..161R |last1=Repsold |first1=J. A. |journal=Astronomische Nachrichten |year=1919 |volume=210 |issue=11 |page=161 |doi=10.1002/asna.19202101102 }}</ref> In 1837 Encke discovered with the Fraunhofer refractor the gap in the [[Saturn's rings|rings of Saturn]], later on named after him, with the Fraunhofer refractor, and in 1838 Galle discovered a further dark ring of Saturn –&nbsp;the C-Ring&nbsp;– as well as three new [[comet]]s from 1839 to 1840.

On 23 September 1846, Galle and astronomy student [[Heinrich Louis d'Arrest|Heinrich Louis d’Arrest]], since 1845 assistant at the observatory, [[Discovery of Neptune|discovered the planet Neptune]], on the basis of positional calculations send by the Frenchman [[Urbain Le Verrier]]. After an initial lack of success they conferred the Le Verrier data with a newly published sheet of the „Berliner Akademische Sternkarte", edited by the Prussian Academy of Science. The letter from Le Verrier had coincidentally reached his close acquaintance Galle on the same day as Encke's 55th birthday, who gave his permission to search around the given celestial positions. At other observatories, the request of the French astronomer was viewed as not having sufficiently promising chances of success, of detecting another large planet on the basis of the deviations between theory and observations for the orbit of [[Uranus (Planet)|Uranus]]. This included [[Paris Observatory]], whose director Le Verrier later became.<ref>Christian Pinter: [http://www.wienerzeitung.at/Desktopdefault.aspx?TabID=3946&Alias=wzo&lexikon=Astronomie&letter=A&cob=4792 Pariser Himmelsmechaniker] {{Webarchive|url=https://web.archive.org/web/20100308133417/http://www.wienerzeitung.at/Desktopdefault.aspx?TabID=3946&Alias=wzo&lexikon=Astronomie&letter=A&cob=4792 |date=8 March 2010 }}</ref> By virtue of the discovery of Neptune, Berlin Observatory gained worldwide renown.

Beyond that they did much work on the calculation of orbits of comets and [[asteroid]]s. Galle was called to become director of the [[University of Wrocław|observatory in Breslau]] in 1851. In 1852 [[Karl Christian Bruhns]] was added as second assistant to Encke and in 1854 he became first assistant. In 1855 [[Wilhelm Foerster]] received a position as second assistant. From 1857 [[Giovanni Schiaparelli]] studied at the institution for two years. When Bruhns transferred to [[Leipzig]] in 1860, Foerster became his successor as first assistant. In the same year Foerster, together with his co-worker [[Otto Lesser]], discovered the asteroid [[(62) Erato|(62)&nbsp;Erato]]. After Encke fell ill in 1863, he stood in as his deputy and in 1865, the year Encke died, he became director of the observatory.<ref>Astronomische Nachrichten Nr. 5088: [http://articles.adsabs.harvard.edu/cgi-bin/nph-iarticle_query?1921AN....212..489B&classic=YES J. Bauschinger: Wilhelm Foerster †]</ref> The observatory at this time was the most important astronomical research and educational institution in Deutschland.<ref>Eine Rezension von Bertram Winde: [http://www.luise-berlin.de/lesezei/blz99_10/text30.htm Wie die Berliner in die Röhre guckten]</ref> In 1873 [[Viktor Knorre]] came as [[Observator]]; by 1887 he had discovered the asteroids [[(158) Koronis|(158)&nbsp;Koronis]], [[(215) Oenone|(215)&nbsp;Oenone]], [[(238) Hypatia|(238)&nbsp;Hypatia]] und [[(271) Penthesilea|(271)&nbsp;Penthesilea]]. From 1884 until the beginning of the 1890s [[Karl Friedrich Küstner]] was also employed as Observator; he discovered in this time the [[polar motion]] as a result of his measurement activities. From 1866 to 1900 [[Arthur Auwers]] compiled, in Berlin, his [[Catalogues of Fundamental Stars|Fundamentalkatalog]], a comprehensive [[star catalog]] containing 170 000 stars.

On the north wing of the observatory was the height reference point for Prussia, known in German as [[Normalnull]]. The marking was formally presented on the 82nd birthday of Kaiser [[William I, German Emperor|Wilhelm&nbsp;I.]] on 22 March 1879. This point was derived from the [[Amsterdam Ordnance Datum]] and marked off 37 meters over zero.<ref>{{cite web|url=http://www.geobasis-bb.de/GeoPortal1/produkte//verm_bb/pdf/1_06_mitt_Major_86-87.pdf |archive-url=https://web.archive.org/web/20150504030204/http://www.geobasis-bb.de/GeoPortal1/produkte//verm_bb/pdf/1_06_mitt_Major_86-87.pdf |url-status=dead |archive-date=4 May 2015 |title=Faksimiledruck zum Normal-Höhenpunkt an der königlichen Sternwarte zu Berlin |author=Walter Major |date=2006 |access-date=30 April 2010}}</ref>

Wilhelm Foerster led the observatory until the end of his life in 1903. It was his impulse that led to the erection of the [[Astrophysikalisches Institut Potsdam|Astrophysikalischen Observatoriums Potsdam]] in 1874 for on the [[Telegrafenberg]] in [[Potsdam]]. On the Telegrafenberg stood formerly the „Telegraphenstation&nbsp;4" which given the hill its name. In the same year Foerster founded the Berlin [[Astronomisches Rechen-Institut|Astronomische Rechen-Institut]] (as "Rechen-Institut zur Herausgabe des Berliner Astronomischen Jahrbuchs"), on the basis of the ever-growing extent of calculation of astronomical [[ephemerides]], which occupied its own building at ″Lindenstraße 91″, but on the grounds and in association with the observatory. Most of the astronomers now worked in this theoretical section&nbsp;– separate from the practical, observational section. The section was led by [[Friedrich Tietjen]], who had been working at the observatory since 1861. In 1865 he discovered the asteroid [[(86) Semele]]. After Tietjens death, [[Julius Bauschinger]] was called to Berlin in 1896 as his successor. In the following year he achieved in making the institute fully independent of the observatory.<ref>Galerie des Universums: {{cite web|url=http://www.galerie-universum.de/gu_2003/webseiten/pnn_12.htm |title=Thema 12. Das Astronomische Recheninstitut |access-date=17 January 2009 }}{{dead link|date=November 2016 |bot=InternetArchiveBot |fix-attempted=yes }}</ref> In 1912 it moved into a new building in [[Berlin-Lichterfelde]]. In 1944 it was placed under the control of the [[Kriegsmarine|Navy]] and transferred to [[Großbothen|Sermuth]] in Saxony to avoid the bombing. After the [[Second World War]] the greater part was brought to [[Heidelberg]] in 1945. Only a small remaining section returned to the observatory, which by now had moved to [[Potsdam-Babelsberg]] and it was again incorporated in 1956.<ref>ARI: {{cite web|url=http://www.ari.uni-heidelberg.de/geschichte/geschichte_kurz.html |title=Zur Geschichte des Astronomischen Rechen-Instituts |access-date=15 January 2009 |url-status=dead |archiveurl=https://web.archive.org/web/20100805080402/http://www.ari.uni-heidelberg.de/geschichte/geschichte_kurz.html |archivedate=5 August 2010  }}</ref>

Because Foerster was not a member of the Academy, the Observatory was separated from the Academy in 1889 and affiliated to the [[Humboldt-Universität zu Berlin|Berlin University]].<ref>Kritische Studien zur Geschichtswissenschaft 121: [{{Google books |plainurl=yes |id=RYO_4hTm59UC |page=90 }} Marita Baumgarten: Professoren und Universitäten im 19.&nbsp;Jahrhundert]</ref> The original Academy Observatory had already been used by the University since the founding of Berlin University in 1809.<ref>HiN: [http://www.uni-potsdam.de/u/romanistik/humboldt/hin/pieper3.htm Zur Wahl Alexander von Humboldts in die Königliche Akademie der Wissenschaften zu Berlin vor 200 Jahren] {{Webarchive|url=https://web.archive.org/web/20080511105440/http://www.uni-potsdam.de/u/romanistik/humboldt/hin/pieper3.htm |date=11 May 2008 }}</ref> In 1890 [[Friedrich Simon Archenhold]] became a worker at the Observatory and erected on the instructions of Foerster a photographic outpost on the [[Halensee]] in Grunewald for the photographing of [[nebulae]].<ref>nordkurier.de: {{cite web |url=http://www.nordkurier.de/index.php?objekt=nk.magazin.heimatgeschichte_ukk&id=523392&eml |title=Haus mit "Himmelskanone" |access-date=24 April 2009 |url-status=dead |archiveurl=https://web.archive.org/web/20090428220456/http://www.nordkurier.de/index.php?objekt=nk.magazin.heimatgeschichte_ukk |archivedate=28 April 2009  }}</ref>

At the end of the 19th century, the rapid growth of Berlin led to the fact that the Observatory which was once on the edge of the city was now fully surrounded by buildings, and therefore observational activities were nearly impossible to a level required for research. In the middle of the 1890s Wilhelm Foerster and others proposed the building of a new observatory outside of the metropolitan area.

In 1904 [[Hermann von Struve]] took over the directorate of the observatory. Under his leadership research was considerably extended and the project of yet another move took on concrete form. After test observations in the surrounding area starting from June 1906 by [[Paul Guthnick]], who had been active at the observatory as Observator since 1906 following on from his training as an assistant at the observatory from 1901 to 1903, the decision made by the Kultusministeriums fell in favor of his recommended location in the [[Park Babelsberg|Schlosspark Babelsberg]] in [[Potsdam]].

The location given up on the Lindenstraße was listed by the [[International Astronomical Union]] (IAU) under their [[List of observatory codes|observatory codes]] as 548.

A few of the observational instruments went to the new location: a new 30&nbsp;cm refractor von [[Carl Zeiss AG|Zeiss]]-[[Johann Georg Repsold|Repsold]], a meridian circle from Pistor & Martins dating from 1868 with 19&nbsp;cm aperture and 2.6&nbsp;m focal length, a 6 Zoll (inch) refractor from and a {{frac|4|1|2}} Zoll refractor from Merz & Mahler.<ref>springerlink.com: {{cite journal |title=Besprechung. Struve, Hermann, Die neue Berliner Sternwarte in Babelsberg. |date=January 1920 |doi=10.1007/BF02448020 |url=https://zenodo.org/record/2133241 |last1=Guthnick |first1=P. |last2=Galle |first2=A. |last3=Ziehen |first3=T. -H }}</ref> After the demolition of the building itself, part of the grounds were used in 1912 for a new road, which has been called Enckestraße since 1927. From 1913, the street was built up with, among others, the (1922).

=== {{anchor|Babelsberg Observatory}} Berlin-Babelsberg Observatory ===
{{Location map | Germany Berlin | label= '''Babelsberg Observatory''' | position= right | background= white |lat_deg= 52 |lat_min= 24 |lat_sec= 18 |lat_dir= N |lon_deg= 13 |lon_min= 6 |lon_sec= 15.12 |lon_dir= E | region= DE-BB | type= landmark | marksize= 8 | float= right
}}

In 1913, the [[#top|Berlin Observatory]] moved again after 78 years in its second home to [[Babelsberg]] (since then it is often referred to as '''Babelsberg Observatory'''). The Observatory in Kreuzberg was cleared out and torn down in August 1913.<ref>{{citation|surname1=Eggert|editor-surname1=Ministerium der öffentlichen Arbeiten|periodical=Zentralblatt der Bauverwaltung|title=Der Neubau der Berliner Sternwarte |issue=43, 34.&nbsp;Jahrgang|publisher=Wilhelm Ernst & Sohn|location=Berlin|pages=318–321|date=30 May 1914|language=German|url=http://opus.kobv.de/zlb/volltexte/2008/4802/pdf/ZBBauverw_1914_043.pdf |access-date=14 August 2010}}</ref> The sale of the land covered the cost of the construction of the new building (1.1 million [[German gold mark|Goldmark]]s and the purchase of new instruments to the sum of 450.000 Goldmarks). The land itself on the Babelsberg in the Schlosspark cost the Royal establishment nothing.<ref name="AIP-history">{{cite web |url=http://www.aip.de/institute/history_de.html |title=Geschichte der Potsdamer Astrophysik |author=AIP |access-date=13 August 2010 |archive-url=https://web.archive.org/web/20120306044603/http://www.aip.de/institute/history_de.html |archive-date=6 March 2012 |url-status=dead }}</ref> The hill giving the area its name is situated about three kilometers north-east of the Telegrafenberg.

The construction of the main building was carried out between 1911 and 1913 by Mertins, W. Eggert, Beringer und E. Wagnernach following the design of Thür and Brüstlein.<ref>potsdam-chronik.de: {{cite web |url=http://potsdam-chronik.de/Potsdamchronik/Chronik/1900-1920/1900-1920.html |title=1900–1920 |access-date=22 April 2009 |url-status=dead |archiveurl=https://web.archive.org/web/20120510040822/http://potsdam-chronik.de/Potsdamchronik/Chronik/1900-1920/1900-1920.html |archivedate=10 May 2012  }}</ref> The move was supervised by the precision engineering company, who also manufactured an [[astrograph]] and a [[Transit telescope|meridian circle]].

The first of the new instruments arrived in spring 1914. In the year after, the placing of a 65&nbsp;cm refractor was completed; it was the first large astronomical instrument from [[Carl Zeiss AG|Carl Zeiss]] in Jena. In 1924 followed the completion of a 120&nbsp;cm [[reflecting telescope]], at the time the second-largest telescope in the world and the largest in Europe. After the Second World War, the reflecting telescope was dismantled and was shipped off to the Soviet Union as [[War reparations|reparations]] (a fate shared by other observing instruments)<ref name="AIP-history" /> It was sent to the [[Crimean Peninsula|Crimea]] complete with its dome;– to reconstruct the [[Crimean Astrophysical Observatory|Crimean Astrophysical Observatory, Simejis]], destroyed in the war.<ref>{{cite web|url=http://www.crao.crimea.ua/index.php?option=com_content&view=article&id=5&Itemid=11&lang=en |archive-url=https://web.archive.org/web/20110716231153/http://www.crao.crimea.ua/index.php?option=com_content&view=article&id=5&Itemid=11&lang=en |url-status=dead |archive-date=16 July 2011 |title=Brief History |author=Crimean Astrophysical Observatory |access-date=14 August 2010 }}</ref>&nbsp;– where it is still in service today. In 2002, the remaining torso of the building was fully restored and completed and received a new dome; since then the library of the [[Astrophysikalisches Institut Potsdam|Leibniz-Institut für Astrophysik Potsdam]] has been accommodated there.<ref>{{cite web|url=http://bauzeitung.de/de/15/...-Potsdam.html?aid=139904&cp=14&action=showDetails |archive-url=https://archive.today/20120721000121/http://bauzeitung.de/de/15/...-Potsdam.html?aid=139904&cp=14&action=showDetails |url-status=dead |archive-date=21 July 2012 |title=Neu in Potsdam. Bibliothek. |author=Jürgen Tietz |access-date=14 August 2010 }}</ref>

Struve remained as director until his death in 1920 –&nbsp; up until 1918 it was still called ''Königliche Sternwarte zu Berlin-Babelsberg'' (or Berlin-Neubabelsberg) and then from 1918 until 1946 it became the ''Universitätssternwarte zu Berlin-Babelsberg'' (or University Observatory at Berlin-Babelsberg.)<ref>AIP: [http://www.aip.de/image_archive/Institute.Portraits.html Institute: Portraits]</ref> After Hermann Struve, the directorship passed over to Paul Guthnick in 1921 and he remained as a long-serving director until 1946. Apart from this post, his main body of work concerned the [[Photometry (astronomy)|photometry]] of stars and the investigation of [[variable star]]s with a new [[photometer]].<ref>H. Schmidt: [http://www.bav-astro.de/rb/rb2007-2/104.pdf Prof. Dr. Paul Guthnick – ein Pionier der lichtelektrischen Photometrie] (PDF; 162&nbsp;kB)</ref>

The new location in the original Schlosspark was a part of the Gemeinde . The "villa settlement" of Neubabelsberg was united in 1938 with the town of to form the town of Babelsberg. Then almost straightaway in 1939 this became incorporated into Potsdam. The designation "Berlin-Babelsberg" was nevertheless retained by the observatory for a few years still. Only after 1945 was the word Berlin discarded.<ref>[http://www.astro.uni-bonn.de/~pbrosche/aa/acta/vol08/vorwort.html 300 Jahre Astronomie in Berlin und Potsdam; Vorwort] auf astro.uni-bonn.de</ref> Ihr IAU-Code ist 536.

By virtue of the nationalization of the [[Sternwarte Sonneberg|Sonnenberg Observatory]] the Universitätssternwarte Berlin-Babelsberg took it on as a new department in 1931, i.e. an out-station in .<ref>4pisysteme.de: {{cite web | url = http://www.4pisysteme.de/observatory/observatory_5_6.html |title=Abteilung Sonneberg der Universitäts-Sternwarte Berlin-Babelsberg |access-date=26 April 2009}}</ref>

===Directors and other workers===
{| class="wikitable"
|-----
! bgcolor="#dfdfdf" colspan="4" | ''Directors'' of Berlin Observatory<ref>ARI: [http://www.ari.uni-heidelberg.de/geschichte/direktoren/index.htm Direktoren des Astronomischen Rechen-Instituts] {{webarchive |url=https://web.archive.org/web/20070720080635/http://www.ari.uni-heidelberg.de/geschichte/direktoren/index.htm |date=20 July 2007 }} (bis 1874 der Berliner Sternwarte)</ref>
|-----
| align="right"  | 1. || 1700–1710 <br /> [[Gottfried Kirch]] (1639–1710)
| align="right"  | 9. || 1756–1758 <br /> [[Johann Jakob Huber]] (1733–1798)
|-----
| align="right"  | 2. || 1710–1716 <br /> [[Johann Heinrich Hoffmann]] (1669–1716)
| align="right"  | 10. || 1758 <br /> [[Johann Albrecht Euler|Johann Albert Euler]] (1734–1800)
|-----
| align="right"  | 3. || 1716–1740 <br /> [[Christfried Kirch]] (1694–1740)
| align="right"  | 11. || 1764–1787 <br /> [[Johann III Bernoulli]] (1744–1807)
|-----
| align="right"  | 4. || 1740–1745 <br /> [[Johann Wilhelm Wagner]] (1681–1745)
| align="right"  | 12. || 1787–1825 <br /> [[Johann Elert Bode]] (1747–1826)
|-----
| align="right"  | 5. || 1745–1749 <br /> [[August Nathanael Grischow|Augustin Nathanael Grischow]] (1726–1760)
| align="right"  | 13. || 1825–1863 <br /> [[Johann Franz Encke]] (1791–1865)
|-----
| align="right"  | 6. || 1752 <br /> [[Jérôme Lalande|Joseph Jérôme Le Francais de Lalande]] (1732–1807)
| align="right"  | 14. || 1865–1903 <br /> [[Wilhelm Foerster|Wilhelm Julius Foerster]] (1832–1921)
|-----
| align="right"  | 7. || 1754 <br /> [[Johann Kies]] (1713–1781)
| align="right"  | 15. || 1904–1920 <br /> [[Hermann von Struve|Karl Hermann von Struve]] (1854–1920)
|-----
| align="right"  | 8. || 1755 <br /> [[Franz Aepinus|Franz Ulrich Theodosius Aepinus]] (1724–1802)
| align="right"  | 16. || 1921–1946 <br /> [[Paul Guthnick]] (1879–1947)
|}
Other workers at the observatory included, for example, [[Johann Friedrich Pfaff]] an der alten Sternwarte, und an der neuen beispielsweise [[Johann Heinrich von Mädler]], [[Gustav Spörer]], [[Franz Friedrich Ernst Brünnow]], [[Karl Theodor Robert Luther|Robert Luther]], [[Friedrich August Theodor Winnecke]], [[Ernst Becker (Astronom)|Ernst Becker]], [[Wilhelm Oswald Lohse]], [[Adolf Marcuse]], [[Eugen Goldstein]], [[Erwin Freundlich]] and [[Georg von Struve]].

==Selected accomplishments==
* [[Johann Franz Encke]] observed a broad variation in the brightness of the [[Rings of Saturn#A Ring|A Ring]] of [[Saturn]] in 1837. The [[Rings of Saturn#Encke Gap|Encke Division]] was later named in honor of his observations of Saturn's rings.
* [[Johann Gottfried Galle]] discovered Saturn's C-ring in 1838.
* [[Johann Gottfried Galle]] and his assistant [[Heinrich Louis d'Arrest]] discovered [[Neptune]] in 1846, near the position computed by [[Urbain Le Verrier]].
* From 1866 to 1900, <!--- George Friedrich Julius --->[[Arthur Auwers]] published his fundamental star catalog of 170,000 stars (''Fundamental-Catalog für Zonenbeobachtungen am Südhimmel und südlicher Polar-Catalog für die Epoche 1900'').

==See also==
* [[List of astronomical observatories]]

==References==
{{Reflist|30em}}

==External links==
*[http://mhdonline.sal.lv/index.php?goto=centers&cid=48 Astrophysical Institute Potsdam – MHD Group] {{Webarchive|url=https://web.archive.org/web/20110722162749/http://mhdonline.sal.lv/index.php?goto=centers&cid=48 |date=22 July 2011 }}
*[https://web.archive.org/web/20051029103225/http://www.be.schule.de/schulen/wfs/pages/hist/WFS-History.html A brief history of astronomy in Berlin and the Wilhelm-Foerster-Observatory]
* [https://web.archive.org/web/20120204112442/http://www.aip.de/institute/history.html Astrophysics Institute Potsdam]

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[[Category:1835 establishments in the German Confederation]]
[[Category:Buildings and structures completed in 1835]]
[[Category:Astronomical observatories in Germany]]
[[Category:Buildings and structures in Berlin]]
[[Category:Frederick William III of Prussia]]