Is this really Norway's largest telescope? This is the largest research-grade optical telescope in Norway, as far as the author is aware of. However, it is possible that
there may be Dobsonian telescopes with apertures
larger than 62 centimetres. Large Dobsonians with quality optics are great for visual use, but not for astrophotography, spectrography and photometry.
Isn't it crazy to build such a big telescope in southwest Norway where it rains so much, and when it isn't raining, the sky is usually cloudy during the dark winter?
Yes.
Is it possible to see anything through the telescope when it is cloudy?
No.
When will you finish the optics? When they have obtained an extremely high paraboloid surface accuracy ;-) Presently, in April 2022, Ronchi and Focault tests show a
good spherical figure on the primary mirror. Reduced polishing tool pressure is required on this type of cellular mirror to avoid print-through of support ribs. Producing a good sphere and
eliminating pits therefore requires longer polishing sessions. After many more hours of cerium oxide, the surface should be ready for parabolizing.
You have been working on this observatory for many years. Why is it taking you so long to finish it?
Two main reasons: 1) my day job occupies a large amount of my brain's resources, and 2) raising my child to adulthood occupies a large amount of my brain's resources ;-)
However, the observatory is finished and producing wide-field astrophotography. It is the narrow field, long focal length optics that I have yet to complete.
Is the observatory open to the public? It is unfortunately not a public observatory.
Can you see all the beautiful colours through a big telescope?
No. With the exception of Mars (orange-yellow), Jupiter (pinkish) and Saturn (creamy-yellowish), even the most sensitive human eyes cannot see colour from nebulae and galaxies. The
brightest nebulae, like the Orion Nebula, seems grey to human eyes, even though it is actually pink. Through a large telescope, one may see it as greenish-grey. This is not real
colour, but an artifact of how our visual system senses and processes extremely weak light. The Universe is very dim. Our eyes are optimised for sunlit and moonlit landscapes which are
gazillions of times brighter. The most dramatic, staggeringly beautiful nebulae and galaxies appear only as barely discernible grey smudges to our eyes. :-( What's more, to view weak objects,
even the planets, through a telescope requires some practice. Many people never manage it.
Why is there no national research-grade observatory in Norway with a telescope larger than 62 centimetres (24 inch)?
There are no gigantic telescopes in Norway because of poor atmospheric conditions: too often cloudy, too much turbulence, too much humidity, too much aurora, too high geographic
latitude. High geographic latitude hides sixty percent of the celestial sphere behind the Earth.
Atmospheric conditions in Norway are not optimal for research in optical astronomy. Mainland Norway extends from 58 to 71 degrees of latitude. That means the night sky is bright from May
until September. Though winter skies are dark, they are often overcast. When skies are clear north of 65 degrees, the aurora may interrupt observations. Even crystal clear skies are often
plagued by high-altitude turbulent air from the jet stream. High latitudes are rarely suitable for large optical telescopes. That is why the world's largest telescopes are located
at low latitudes but high altitudes, in dry mountain deserts: Atacama in northern Chile, Mauna Kea in Hawaii, volcanic summits in the Canary Islands, in Australia
and South Africa. The goal is to have as little air and moisture over the observatory as possible. However, one advantage of the Norwegian skies is that the air is very transparent.
There is little dust.
Why does a Cassegrain optical system need a field corrector lens?
Cassegrain optics produce a curved focal plane. Even the prime focus is curved. This is negligible when one uses only the central part of the field, as when using a planetary camera with a
small imaging chip. It is a problem when one uses a large CCD chip such as the Kodak KAF-16803 with imaging area: 36.8 x 36.8mm (1359 sq mm). Without a focal plane flattener (field corrector
lens) the inner part of the field is in focus when the outer part is not, and vice-versa. A field corrector placed at the correct distance from focus flattens the focal plane.
Why is the telescope mount so massive (550 kg) ?
A steady mount is a heavy mount. If possible, mounts should be designed to carry twice the required equipment load. ASA's DDM160 mount has a 160 mm diameter polar aksel. The mount can
carry a total of 600 kg: 300 kg instrument load + 300 kg counterweight. The 62 cm telescope carries 150 kg instrument load + 150 kg counterweight load.
Why is it called Dinium? Because of my day-job, marine palynology; the paleontology of fossil microplankton. "Dinium" is a
common suffix used in the naming of dinoflagellate genera, for example, Ctenidodinium, Spinidinium, Palaeoperidinium and MANY more. Fossil dinoflagellates are very
common in sedimentary rocks, especially rocks deposited as fine-grained sediments in an open marine environment. Dinoflagellates have existed for over 240 million years, which is
coincidentally equivalent to a single rotation of our galaxy. Palynologists use fossil dinoflagellates to map sedimentary rocks from the Triassic to the present over the entire
planet.
And besides, "dinium" has a nice Latin ring to it. ;-)
