Centurion Equipment

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The telescope manufacturer is now retired, the SBIG camera is outdated....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.

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...

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. 


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...
Switches are implemented on the dome opening slot, so that the PC can monitor when the dome is fully opened or fully closed. 
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.

Centurion 18" polar alignment

This is a permanent polar alignment. The telescope latitude adjustment is done using screws on the telescope legs
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.


ST8E Camera

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

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.

Remote operation

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.