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The Dome at Rooisand and the Instrument
In contrast to
other amateur observatories in Namibia we have opted for a dome instead of the
customary structure with a sliding roof. It is a 3.2 metre dome from
Baader Planetarium GmbH with an electrical drive in Azimut.
Advantages:
The dome provides shelter against the wind, which up on the
mountain top blows quite furiously at times, it acts as a dew shield and
effectively blocks out scattered light when observations are done below the
dome with portable telescopes.
Since the instrument is mounted almost 8 metres above the ground
it stands clear of low layers of air. Compared to a position on the ground, the
improvement in seeing conditions is considerable.
This is clearly noticeable at wider telescope apertures. |
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A
platform of about 4 m² in front of the door leading into the dome affords
spectacular views of the entire night sky.
The instrument is mounted
onto a concrete base which is totally isolated from the stairwell tower and
dome. Thus it is absolutely torsion resistant and free from vibration. The
concrete in the four supporting pillars was compressed with high-frequency
vibrators.
The picture
below shows a panoramic view from northeast to southeast as seen from the
tower's platform. |
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The Telescope
Rooisand's
telescope consists of a combination of:
- · Zeiss 150 mm APQ refractor, f = 1200 mm,
f:8
- · Zeiss 80 mm AS refractor, f = 840 mm,
f:10.5
- · a Celestron 14, selected for its optical quality, with a 354
mm aperture, f = 4000 mm, f:11
The two large
telescopes can be equipped with 2" as well as 1¼" accessories, whereas
the small one supports only 1¼" accessories. A wide array of accessories
is available for all three telescopes. Download a detailed
list of accessories in pdf format (aprox.
150Kb). |
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Here
some "first light" pictures, taken at the Zeiss APQ with a Canon EOS 300D (M20
with EOS 350d) shortly after the dome was completed in late 2004. All the
pictures were taken without correcting darkness and flat field (those with a
short exposure time without alignment control). Click on the preview pictures
for a larger version.
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| Messier
42 |
5 single images, each 30
second aat ISO 400 added |
| NGC 3372
(Eta Carinae) |
single image, 300 second
at ISO 800 |
| NGC 5139
(Omega Centauri) |
10 single images, each
30 seconds at ISO 800 added |
| NGC 4755
(Jewel Box) |
single image, 300
seconds at ISO 400 |
| Messier
8 |
2 single images, each
300 seconds at ISO 800 |
| Messier
20) |
single image, 300
seconds at ISO 800 |
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The
first high definition CCD images were also taken at the Zeiss refractor, with
an SBIG-ST 6303, during summer 2005. Click on the preview pictures for a larger
version (note: about 700 Kb each).
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| Messier 17, © D. Unbehaun |
NGC 5128 17, © D. Unbehaun |
NGC 6822, © D. Unbehaun |
NGC 7293, © D. Unbehaun |
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| Datas for
the CCD images : |
| Messier 17 |
3
single images, each 10 minutes where added and averaged, |
| NGC 5128 |
Addition of 2 single images, each 30 minutes exposed. |
| NGC 6822 |
Additon of 3 single images, each 30 minutes exposed. NGC 6822 is a
very dimm galaxie of the local group, and in this image partly resolved into
single stars. |
| NGC 7293 |
Addition of 2 single images, each 30 minutes exposed. Pay attention
to the details in the inside of the Helix nebulae. |
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The three telescopes are aligned with total precision. Up to a
magnification of a hundred times the target of observation is exactly centred
in the field of view of any of the telescopes.
A mounted rigid camera
ball head is also available to carry the heaviest telephoto
lenses. |
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The Mount
The combination of
telescopes is fitted on a GoTo mount - GTO 1200 - by Astro Physics. The total
weight of the telescopes is only half of the nominal capacity of the GTO 1200,
which makes the combination extremely solid and absolutely free from vibration.
The GTO 1200 features a fully automatic parking mode. Just switch off
the power at the end of your observation and simply switch it back on when you
continue (also by day). The mount does not need to be realigned, and it is easy
to control with an ergonomic hand-held computer.
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The GTO
1200 can also be operated with a laptop using the planetarium software GUIDE
8.0 and TheSky 5.0. An input compatible with SBIG allows automatic guiding with
SBIG CCD cameras via CCDOPS.
The dome has its own internet connection so
that software and upgrades can be downloaded and installed easily.
 ... by the way, the entire area
around the observatory is enclosed with an electrical fence. Don't worry, this
is not because of bad people - we don't have any of those - but mostly because
of nosy baboons and other larger animals like antelope and
zebra...
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Observatory and
Instrument
