Sonnenborgh Observatory

Sonnenborgh is the name of the southeast bastion of the historic fortifications of the city of Utrecht in the Netherlands. It houses the astronomical observatory of the University of Utrecht, which is now used as a museum and, together with the University Museum attracts 60,000 visitors annually.

History

The Bastion Sonnenborgh 1552 Emperor Charles V built in order as part of the fortification of Utrecht. Later, she also hosted scientific institutions. The University of Utrecht took the bastion since 1639 as a herb garden. 1695 financed the Municipality of the city of Utrecht, the chemist Johann Conrad Barchusen here a laboratory. In the 1840s, the Dutch scholar Christoph Buys- Ballot focused on a Sonnenborgh a cellar for magnetic observations. Frederick Wilhelm Krecke (1812-1882) began here on December 1, 1849 regular weather observations. 1853 founded Buys Ballot the observatory. Sonnenborgh was from 1854 to 1897 the seat of the Royal Netherlands Meteorological Institute. From 1937 to 1963, Marcel Minnaert was director of the observatory and had in the Sonnenborgh his living quarters. Current director is his pupil Cornelis de Jager.

When Jan David Zocher 1850 docked the park Zocherplantsoen, large parts of the bastion were covered with earth. From 1998 to 2003, these areas were excavated archaeologically investigated and restored. Today, parts of the bastion be used as a museum. The Sonnenborgh is also the seat of the Foundation De Koepel, a Dutch umbrella organization for the popularization of astronomy, meteorology and space.

Museum and Observatory

Museum and Observatory Sonnenborgh (Dutch Sonnenborgh - museum & sterr monitored) represents a unique combination of military and science museum dar. On a tour you can visit the casemates of the historic fortification with its 3 meter thick walls. In the area of the observatory the visitor is presented with a series of astronomical and meteorological devices. About a coelostat the sunlight is directed directly into the sun room accessible for visitors. With this device, the Utrecht Solar Atlas ( A photometric atlas of the solar spectrum) was created in 1940, which is also still in use today in many observatories. In the north tower is also to observe the Sun, a Fraunhofer telescope from 1826, combined with an H - α filter by Bernard Lyot. In the domed east tower an achromatic 200 -mm refractor Lichtenknecker VAF 200 and a Celestron -14 telescope for nighttime observation of planets and nebulae are housed. From the year 1863 the 260 -mm telescope in the company Steinheil, 1888 equipped with a lens Merz, in the south tower of the observatory. The Meridian Hall, named Between North and South Tower after the requirements herein meridian circle. The museum has also a library, a lecture room and the cycloidal space, named after the curved shape of an outer wall in the form of a cycloid, which is used for temporary exhibitions.

The observatory has the IAU code 015