A visit to the observatory of Bonn University at 'Hoher List' in the Eifel, a landscape that was formed by volcanoes eons ago.

Between Christmas and New Year of 2003 my friend Arndt and I visited Dr Joerg Schumann of Observatorium Hoher List, a departement of the University of Bonn, to pick up some magazines amd books. We got a tour of three telescopes (out of 5) and saw some interesting things.

First, a view from the office to the south with the dome of the 1 m Cassegrain reflector:
OHL view south

1 meter Cassegrain
Cassegrain D = 106 cm (42"), f = 14.5 m, constructed in 1965, used to test equipment that will be used at other observatories like the VLT. The white screen near the top of the dome is used to take 'flats' for the CCD cameras. It is illuminated by several light bulbs which sit in table tennis balls, mounted on the upper ring of the secondary holder.

This was actually the last telescope we saw. The first one was the 0.6 meter Ritchey-Chretien instrument whichs dome is accessible from the office building.

0.6 meter RC
This D = 60 cm (24"), f = 4.8 m, constructed in 1984, Ritchey-Chretien instrument looks incredible good to me and rests on a Zeiss mounting, similar, but more recent in make, to the one we have at our public observatory in Hildesheim. The big black ring just beneath the mirror cell is a focussing handle which shifts the smaller grey tube by 8 mm per turn, that is what I would call precision focussing. And it will work with equipment of considerable weight as well. Behind the main tube and to the left is the lower end of a refractor made by Lichtenknecker, a Belgian company well known for its precise optics. We learned that the original main mirror of this 0.6 meter telescope broke by accident when it was brought up the hill for mounting. Unfortunately the assurance company had only agreed to cover breakage due to a traffic/vehicle accident, anything else wasn't covered. So a second mirror was made on a somewhat unclear agreement between the University and the optician, who left a bad zone in the glass, giving the telescope an overall performance that leaves much to be desired. You know that I find some fun in pushing glass and making telescope mirrors, you can imagine what went through my head on hearing this (hehe).

One of the older instruments is the double refractor which moved here from Bonn:
Bonn Double Refactor
The visual diameter is 36 cm (14.4 inch), f = 5.4 m, the photographic objective is of 30 cm (12"), f = 5.1 m, constructed in 1899, at Hoher List since 1965. As far as I know it is used for training purpose. Here Dr Schumann is moving the telescope to get rid of some water that pooled on the plastic cover that protects the lenses. Unfortunately all domes need repair, mainly at the shutters.

This dome is equipped with a platform that can be raised and lowered by hydraulics. So I took advantage of the staircase which led to a higher point and took the following picture:
Dr Schumann and Arndt

In the background you see the old operating desk. Dr Schumann, who was in charge of the technical equipment of the observatory and head of the electronics laboratory until his retirement, made sure that nothing was removed or destroyed before a working alternative was available and thoroughly tested. Therefor also the old electronics box of the 1 meter Cassegrain is still there (see below).

Today the speciality of the workshop and electronics lab is the manufacture of fast shutters for the big telescopes in Chile, Hawaii and elsewhere. To learn more about this project, please see this link: http://www.astro.uni-bonn.de/~ccd/shutters/


Cassegrain Electronics Cabinet

Wow, do I like to observe a night with one of the telescopes? Yes, indeed. When I am grown I will have a decent telescope as well ;-)

Have fun, take care, and clear skies for all,
Chris

all pics ©Chris Plicht, reduced in resolution (600x450). If someone likes to have one in full res (1600x1200) , please e-mail me.