1. C2PU TELESCOPES © C2PU, Observatoire de la Cote d’Azur, Université de Nice Sophia-Antipolis Jean-Pierre Rivet CNRS, OCA, Dept. Lagrange jean-pierre.rivet@oca.eu Version 02, 01/09/2015

2. C2PU: two telescopes 19/12/2015C2PU-Team, Observatoire de Nice2 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 restricted omicron@C2PU: ready for use

3. C2PU Telescopes : optical combinations 19/12/2015C2PU-Team, Observatoire de Nice3 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 !

4. C2PU Telescopes : optical combinations 19/12/2015C2PU-Team, Observatoire de Nice4 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 !

5. C2PU Telescope : optical combinations 19/12/2015C2PU-Team, Observatoire de Nice5 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

6. How focalization is done 19/12/2015C2PU-Team, Observatoire de Nice6 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 !

7. Sample image 19/12/20157 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

8. C2PU Telescopes : optical combinations 19/12/2015C2PU-Team, Observatoire de Nice8 “Coudé” focus Primary mirror (parabolic) Secondary mirror (hyperbolic) F = 36400 mm D = 1040 mm F / 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)

9. Optical configurations 19/12/2015C2PU-Team, Observatoire de Nice9 West dome Omicron 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)

10. Mount coordinates 19/12/2015C2PU-Team, Observatoire de Nice10 Equatorial plane North pole Sun local meridian 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 coordinates for a telescope equatorial mount, delivered by its angular encoders !!! r Beware ! H angle defined from star meridian to local meridian !

11. Mount coordinates and equatorial mount 19/12/2015C2PU-Team, Observatoire de Nice11 Equatorial plane North polar axis Sun local meridian H  r Hour angle axis Declination axis  H Mount coordinates Telescope equatorial mount

12. Equatorial mount 19/12/2015 12 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

13. Equatorial mount 19/12/2015 13 North polar axis Local meridian  to equatorial 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..

14. Equatorial mount 19/12/201514 North polar axis Local meridian  to equatorial 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..

15. Equatorial mount 19/12/201515 North polar axis 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 mount is tilted on the horizon, of an angle equal to the local latitude

16. Equatorial mount 19/12/201516 North polar axis 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 mount is tilted on the horizon, of an angle equal to the local latitude

17. C2PU Telescopes : equatorial yoke mount 19/12/2015C2PU-Team, Observatoire de Nice17 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.

18. Omicron Telescope : accessible zone 19/12/2015C2PU-Team, Observatoire de Nice18 Elevation: h > 18° Declination:  < 60° Hour angle: -6 h < H < +6 h

19. Omicron Telescope : accessible zone 19/12/2015C2PU-Team, Observatoire de Nice19 Elevation: h > 18° Declination:  < 60° Hour angle: -6 h < H < +6 h

20. 19/12/2015C2PU-Team, Observatoire de Nice20 ENJOY !