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C2PU TELESCOPESC2PU TELESCOPES
© C2PU, Observatoire de la Cote d’Azur,
Université de Nice Sophia-Antipolis
Jean-Pierre RivetCNRS, OCA,Dept. [email protected]
Version 02, 01/09/2015
C2PU: two telescopes
21/04/23 C2PU-Team, Observatoire de Nice 2
West dome
East dome
West (“Ouest” in French): omicron telescope (“omicron”: Greek leter for “O”)East (“Est” in French): epsilon telescope (“epsilon”: Greek letter for “E”)
epsilon@C2PU: ready for use; access restrictedomicron@C2PU: ready for use
C2PU Telescopes :optical combinations
21/04/23 C2PU-Team, Observatoire de Nice 3
Cassegrain secondary focus
Primary mirror
(parabolic)
Secondary mirror
(hyperbolic)
F 13000 mmD = 1040 mmF / D = 12.5
• Magnifies a lot• Narrow field of view• Best for planetary imaging
CCD camera
at secondary focus
AVAILABLE
ON BOTH
TELESCOPES !
C2PU Telescopes :optical combinations
21/04/23 C2PU-Team, Observatoire de Nice 4
Pure primary focus configuration
Primary mirror
(parabolic)
CCD camera
at primary focus
F 2995 mmD = 1040 mmF / D = 2.88
Simple, perfect at center,BUT strong coma aberration off-axis !
C2PU Telescope :optical combinations
21/04/23 C2PU-Team, Observatoire de Nice 5
Prime focus configuration with Wynne corrector
Primary mirror
(parabolic)
CCD camera
at corrected primary focus
F 3297 mmD = 1040 mmF / D = 3.17
Much better !3-lens Wynne
coma corrector
How focalization is done
21/04/23 C2PU-Team, Observatoire de Nice 6
Prime focus configuration with Wynne corrector
Focalization
All the focal assembly (Wynne corrector + Camera)can move up and down.Fully motorized, computer-operated,with position gauge
AVAILABLE
ON OMICRON
TELESCOPE ONLY !
Sample image
21/04/23 7
Galaxy NGC 6946:Distance: 10 MlyApp. size: 9.8 11 ‘
Telescope: omicron@C2PUFocus: Primary + ParraCorCamera: SBIG ST4000 XCMExposure: 90 x 2mnDate: 14/09/2012Author: David Vernet
C2PU Telescopes :optical combinations
21/04/23 C2PU-Team, Observatoire de Nice 8
“Coudé” focus
Primary mirror
(parabolic)
Secondary mirror
(hyperbolic)
F = 36400 mmD = 1040 mmF / D = 12.5
• Magnifies a lot• Very narrow field of view• Fixed focus• Best for “big” focal sensors
CCD camera
at coudé focus
AVAILABLE
ON EPSILON
TELESCOPE ONLY !
Optical bench
Celestial North pole
Polar axis
3rd mirror
(flat)
4th mirror
(flat)
5th mirror
(flat)
Optical configurations
21/04/23 C2PU-Team, Observatoire de Nice 9
West domeOmicron telescope East dome
Epsilon telescope
Cassegrain focus
F/12.5 or F/9.0
(with focal reducer)
Prime focus +
Wynne corrector
F/3.2
Cassegrain focus
F/12.5 or F/9.0
(with focal reducer)
Coudé focus F/35
(in progress)
Mount coordinates
21/04/23 C2PU-Team, Observatoire de Nice 10
Equatorial plane
Nor
th p
ole
Sun
loca
l mer
idia
n
H
• Origin: observatory position (topocentric).• Fundamental plane: Equatorial plane• Polar axis: Geographic North pole• Zero direction: Local meridian• H : hour angle (in hours !)• : declination (in degrees)• r : topocentric distance
These are the natural coordinatesfor a telescope equatorial mount,delivered by its angular encoders !!!
r
Beware !H angle defined from star meridian to local meridian !
Mount coordinatesand equatorial mount
21/04/23 C2PU-Team, Observatoire de Nice 11
Equatorial plane
Nor
th p
olar
axi
s
Sun
loca
l mer
idia
n
H
r
Hour angleaxis
Declination
axis
H
Mount coordinates
Telescopeequatorial
mount
Equatorial mount
21/04/2312
Equ
ator
ial p
lane
Earth’s rotation
Earth is in rotation,
but stars are “fixed” !
So, you need an Equatorial mount...
Eppur si muove ! (Galileo Galilei, 1633)
Northpolar axis
Equatorial mount
21/04/2313
Northpolar axis
Local meridian
to
equ
ator
ial p
lane
Equ
ator
ial p
lane
If my observatorywas at North Pole..
Earth’s rotation
Observatory
Telescope’s rotationEarth’s rotation could becompensated easily, by an opposite rotationof the telescope’s mount
This is an Equatorial mount..
Equatorial mount
21/04/23 14
Northpolaraxis
Local meridian
to
equ
ator
ial p
lane
Equ
ator
ial p
lane
// to Northpolaraxis
Observatory
If my observatoryis NOT at North Pole..
Earth’s rotation can becompensated as well, by an opposite rotationof the telescope’s mount
This is an Equatorial mount..
Equatorial mount
21/04/23 15
Northpolaraxis
Local meridian
to equatorial plane
// to North polar axis
Observatory
Zenith
Equatorial plane
Latitude
Horizontal plane
Latitude
Equatorial mount:the North polar axis of the mountis tilted on the horizon, of anangle equal to the local latitude
Equatorial mount
21/04/23 16
North
pola
rax
is
Loca
l m
erid
ian
to
equ
ator
ial p
lane
// to
Nor
th p
olar
axis
Obs
erva
tory
Zen
ith
Equat
oria
l pla
ne
Latitude
Horizontal planeLatit
ude
Equatorial mount:the North polar axis of the mountis tilted on the horizon, of anangle equal to the local latitude
C2PU Telescopes :equatorial yoke mount
21/04/23 C2PU-Team, Observatoire de Nice 17
South pillar
North pillar
Yoke
Polar axis
Declin
atio
n ax
is
H
Telescope’s tube
(Serrurier structure)
Yoke mount “pros and cons” :•Very stable mechanically•Low flexion•Limitations in accessible sky zone (blind angles). ... More on that later.
Omicron Telescope :accessible zone
21/04/23 C2PU-Team, Observatoire de Nice 18
Elevation:h > 18°
Declination:< 60°
Hour angle:-6h < H < +6h
Omicron Telescope :accessible zone
21/04/23 C2PU-Team, Observatoire de Nice 19
Elevation:h > 18°
Declination:< 60°
Hour angle:-6h < H < +6h
21/04/23 C2PU-Team, Observatoire de Nice 20
ENJOY !