C2PU TELESCOPES © C2PU, Observatoire de la Cote d’Azur, - PowerPoint Presentation

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C2PU TELESCOPES

©

C2PU, Observatoire de la Cote d’Azur, Université de Nice Sophia-Antipolis

Jean-Pierre Rivet

CNRS, OCA,

Dept. Lagrangejean-pierre.rivet@oca.eu

Version 02, 28/08/2016

C2PU: two telescopes

14/02/2017

C2PU-Team, Observatoire de Nice

2

West dome

East dome

West

(“

O

uest” in French):

omicron telescope

(“

omicron

”: Greek leter for “

O

”)

East

(“

E

st” in French):

epsilon telescope

(“

epsilon

”: Greek letter for “

E

”)

C2PU Telescopes :

optical combinations

14/02/2017

C2PU-Team, Observatoire de Nice

3

Cassegrain secondary focus

Primary mirror

(parabolic)

Secondary mirror

(hyperbolic)

F 13000 mm

D = 1040 mm

F / 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

14/02/2017

C2PU-Team, Observatoire de Nice

4

Pure primary focus configuration

Primary mirror

(parabolic)

CCD camera

at primary focus

F 2995 mm

D = 1040 mm

F / D =

2.88

Simple, perfect at center

,

BUT

strong coma

aberration off-axis !

C2PU Telescope :

optical combinations

14/02/2017

C2PU-Team, Observatoire de Nice

5

Prime focus configuration with

Wynne corrector

Primary mirror

(parabolic)

CCD camera

at

corrected

primary focus

F 3297 mm

D = 1040 mm

F / D =

3.17

Much better !

3-lens Wynne

coma corrector

How focalization is done

14/02/2017

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

14/02/2017

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Galaxy NGC 6946:

Distance:

 10 Mly

App. size: 9.8  11 ‘

Telescope: omicron@C2PU

Focus: Primary + ParraCor

Camera: SBIG ST4000 XCM

Exposure: 90 x 2mn

Date: 14/09/2012

Author: David Vernet

C2PU Telescopes :optical combinations

14/02/2017

C2PU-Team, Observatoire de Nice

8

“

Coudé

” focus

Primary mirror

(parabolic)

Secondary mirror

(hyperbolic)

F = 36400 mm

D = 1040 mm

F / D

=

35

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

14/02/2017

C2PU-Team, Observatoire de Nice

9

West dome

Omicron telescope

East dome

Epsilon telescope

Cassegrain focus

F/12.5 or F/9.0

(with focal reducer):

Spectroscopy,

Narrow field imaging.

Prime focus +

Wynne corrector

F/3.2:

Photometry,

Astrometry,

Occultations.

Wide field imaging.

Cassegrain focus

F/12.5 or F/9.0

(with focal reducer)

Spectroscopy,

Narrow field imaging.

Coudé

focus F/35

Only for invited

instruments

Equatorial mount

14/02/2017

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Equatorial plane

Earth’s rotation

Earth is in rotation,

but stars are “fixed” !

So, you need an

Equatorial mount...

Eppur si muove !

(Galileo Galilei, 1633)

North

polar axis

Equatorial mount

14/02/2017

11

North

polar axis

Local

meridian

 to e

quatorial plane

Equatorial plane

If my observatory

was at North Pole..

Earth’s rotation

Observatory

Telescope’s rotation

Earth’s rotation could be

compensated easily, by

an opposite rotation

of the telescope’s mount

This is an

Equatorial mount..

Equatorial mount

14/02/2017

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North

polar

axis

Local

meridian

 to e

quatorial plane

Equatorial plane

// to North

polar

axis

Observatory

If my observatory

is

NOT

at North Pole..

Earth’s rotation can be

compensated as well, by

an opposite rotation

of the telescope’s mount

This is an

Equatorial mount..

Equatorial mount

14/02/2017

13

North

polar

axis

Local

meridian

 to e

quatorial plane

// to North polar axis

Observatory

Zenith

E

quatorial plane

Latitude

Horizontal plane

Latitude

Equatorial mount:

the North polar axis of the mount

is

tilted on the horizon

, of an

angle equal to the local

latitude

Equatorial mount

14/02/2017

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North

polar

axis

Local

meridian

 to e

quatorial plane

// to North polar axis

Observatory

Zenith

E

quatorial plane

Latitude

Horizontal plane

Latitude

Equatorial mount:

the North polar axis of the mount

is

tilted on the horizon

, of an

angle equal to the local

latitude

Mount coordinates

14/02/2017

C2PU-Team, Observatoire de Nice

15

Equatorial plane

North

pole

O

local meridian

H



Origin:

mount axes intersection

(

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 coordinates

for a telescope equatorial mount,

delivered by its angular encoders !!!

r

Beware !

H angle defined from star meridian to local meridian !

Mount coordinates

and equatorial mount

14/02/2017

C2PU-Team, Observatoire de Nice

16

Equatorial plane

North

polar axis

local meridian

H



r

Hour angle

axis

Declination

axis



H

Mount coordinates

Telescope

equatorial

mount

O

C2PU Telescopes :

equatorial yoke mount

14/02/2017

C2PU-Team, Observatoire de Nice

17

South pillar

North pillar

Yoke

Polar axis

Declination axis



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

14/02/2017

C2PU-Team, Observatoire de Nice

18

Elevation:

h > 18°Declination:< 60°Hour angle:

-6

h

< H < +6

h

Epsilon Telescope :accessible zone

14/02/2017

C2PU-Team, Observatoire de Nice

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Elevation:

h > 21°Declination:< 60°Hour angle:

-5.3

h

< H < +5.3

h

14/02/2017

C2PU-Team, Observatoire de Nice

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ENJOY !