I'm using successfully the same equipment since 2002....
The telescope manufacturer is now retired, the SBIG camera is outdated....
But cross fingers, everything still works nicely... I just had to recoat the
telescope mirror in 2013, change the LRGB filters in 2017 and buy a second
hand PC with serial and parallel ports in 2019...
In 2019 I started wide field imaging (6° x 4°) using a Canon camera with a
fixed focal 200mm F2.8 lens attached to the telescope.
| Location |
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Since 2005, the observatory is located in France, Normandy, about 10
miles from the
city of Caen. The view towards South horizon is clear, with only a few
distant trees and no city lights.
The only problem is the weather, with not so many clear sky nights per
year...
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Telescope |
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The Centurion 18" is a very fast F2.8 telescope,
designed for the small area size of CCD chips. It is attached to an ST8E
CCD camera. Telescope, camera and dome
are fully under computer control.
After 10 years, the mirror had to be re-coated. This has been very
successfully done by
Mirro-Sphere in 2013. |
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Dome |
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I use a 10' dome from
Technical
Innovations mounted on
a circular concrete wall. Dome opening and rotation are
motorized. The PC constantly monitors the telescope r.a. dec coordinates
and, together with time, latitude and longitude informations transforms
them into dome azimuth position. Dome position accuracy is about
2°.
more about dome
construction... |
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Switches are implemented on the dome opening slot, so
that the PC can monitor when the dome is fully opened or fully
closed. |
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Dome rotation is monitored by the PC by receiving impulses
from the dome motors. A switch is also implemented to detect the dome home
position. |
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Centurion 18" polar alignment |
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This is a permanent polar alignment. The telescope latitude
adjustment is done using screws on the telescope legs |
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The telescope is mounted on a very strong piece of wood,
which rests on the floor concrete. The piece of wood can be adjusted in
rotation providing telescope azimuth adjustment.
The polar adjustment has been carried out using long term declination
drift of stars close to the South and East equator. |
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ST8E Camera |
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The
ST8E camera (1536 x 1020 16 bit pixels) has two stage
cooling and additional water cooling.
The camera is attached to a CFW8 filter wheel (Clear, Red, Green,
Blue, H-alpha). I typically operate the
camera at -20°C. The optical configuration is fixed, which allows for a
single set of flat field frames. Field of view is about 35' x 23', with a
pixel sampling of 1.4 arc sec. |
Wide field imaging |
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To image large objects, I use a Canon camera with a fixed
focal 200mm F2.8 lens. This yields to a field of view of approx 6° x 4°.
The camera is attached to the telescope using a home made 3D printed
support. The camera points at current telescope dec. +10°.
The camera is remote controlled by a tablet using WiFi.
Images are recorded in raw mode, typically 10x30s exposures at ISO 3200.
The main difficulty is to get good focusing as this cannot be remote
controlled.
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Remote operation |
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Telescope, dome and CCD camera are operated from an old P4
2GHz PC running under Windows XP, as I still need serial and printer
interfaces.
Focusing is controlled by the box on the right.I developped specific control software, with scripting possibilities.
It is possible to setup an automatic night observation session. When the
session is finished, or if clouds (or rain...) come in, then hopefully the dome will
close and the telescope and CCD will power off.
The tablet allows manual remote control
from the Canon camera through WiFi for wide field imaging. |
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