PROJECT OF THE 130 cm TELESCOPE FOR THE SKALNATÉ PLES O OBSERVATORY

1. PROJECT OF THE 130 cmTELESCOPE FOR THE SKALNATÉ PLESO OBSERVATORY Jozef Žižňovský Stakčín, December 2012

2. The described system consists of a 1.3m alt-az mounted Cassegrain-Nasmyth telescope with two Nasmyth focal stations. Both Nasmyth focal stations are equipped with a field derotator. It contains a control system and a software communicating with the dome control unit and a meteostation. In principle it is arobotictelescope. Manufacturer and supplier: ASTELCO SystemsGmbH, München Instruments in the foci: CCD camera for near UV, visual and red spectral region IR CCD cameraforinfrared region Echellespektrograph It will be providedin the frame of the EuropeanRegional DevelopmentFund in threesteps: 1. Telescope: till the end of 2013 2. Dome computerisation: 2013 3. Focal instruments andinfrastructure: Spring 2014

4. 1. TELESCOPE 1.1. Optics

5. The primary mirror is a thin low expansion glass meniscus. Its shape and optical performance therefore has to be actively controlled during the observations. The active mirror support system consists of a combination of an 18 point whiffle-tree support and 9 axial actuators. The actuators are controlled by a Shack-Hartmann sensor unit as a part of the telescope system, like the autofocus thermal control. The Shack-Hartmann unit allows checking the online alignment performance of M1 and M2 mirrors and helps to regain the collimation of the optics after recoating. The primary mirror is fixed radially by a 4 point preloaded spring pad system, which guarantees the permanent position of M1 during all telescope movements between zenith and horizon positions as well as at high slewing rates of the telescope. The surface accuracy of the optical system will be proven by interferograms at factory acceptance. At final acceptance, there will be on-sky tests carried out at the Observatory with the supplied Shack-Hartmann sensor unit available at the Nasmyth focal station.

6. 2. Mechanics 2.1 Dimensions * Calculated from the lower surface of the telescope basis** Dimensions after the preliminary design phase

7. 2.2 Telescope structure The structure of the telescope is a special, super-compact “ASTELCO Design”. The telescope tube is a welded Serrurier truss design made from steel.This guarantees a minimal and predictable bending of the tube.All welded parts of the telescope are annealed to relax tensions. This very stiff and rigid design reaches high values for the eigenfrequencies of the system and therefore allows observing at wind speeds up to 15 m/s. The telescope’s central part connects the upper and lower truss sections and holds the combined motorized M1/M3 mirror doors. This section connects the tube assembly by means of two hollow flanges to the fork arms of the mount. Through these hollow flanges the light path of the telescope is sent to one of the 2 Nasmyth foci. A motorized rotating and self-centering M3 unit is provided to reach both Nasmyth foci by software control. Rapid and precise focus change between the two Nasmyth foci gets a simple standard task to be able to use two different instruments at two foci at practically the same time. The lower Serrurier truss part holds the mirror cell with the M1 primary mirror. The mirror cell allows easy access for maintenance – for mounting and dismounting the primary mirror a special ASTELCO tool is supplied.

8. M2 M3 M1

9. 2.3 Telescope mount and drives The tube assembly is mounted between both fork arms of the alt-az mount. The fork arms are connected to the mounting base plate. On the upper end of the fork arms the bearing housings, the encoders and the motors are located. The accuracy of the perpendicularity of axes is < 10 arc sec; residual errors are correctedby the software.

10. FOCAL INSTRUMENTS • CCD camera for near UV to red spectral region • Quantum efficiencyin the interval of 400-760nm: 80% • Sensor size 10k x 10k, class: 1 • Pixel size: 8-10 µm • Interface for communication with the computer via fiber optic cable • (1 Gbit) • Dark current maximum: 0.01e‐/pixel/sec • Readout noise: less than 5e- (rms) • 16 bit AD converter • Cooling with cryotiger to < -100° C • Example: Spectral Instruments1110S • http://www.specinst.com/Brochures%20Rev%20A/1100S-camera-broch_RevA.pdf

11. 2. IR CCD camera for near infrared region • Quantum efficiencyin the interval of900-2 300nm: 70% • Sensor size2k x 2k, HgCdTetechnology, class 1 • Pixel size: 15 µm • Dark current maximum: 0.01e- /pixel/sec • Readout noise: less than20e- (rms) • 16 bit AD converter • Cooling with a Stirling engine to 70° K (-203° C) • without the necessity of liquid Nitrogen use • Example: Teledyne Scientific • (Manufacturer and supplier of detectors for • the Hubble Space Telescope and the James Webb Space Telescope) • http://www.teledyne-si.com/infrared_visible_fpas/index.html

12. 3. Spectrograph • Hihg-dispersionéchelle spectrograph to the Nasmyth focus: • R = 40 000for seeing 3" • Spectral region: 400-760nm • CCD camera2k x 2k • Calibration lamps for ThAr line spectrum and continuum light • Interchangeable slits(apertures) • Software for remote control of the spectrograph and its CCD camera Manufacturer, contractor: Lasertechnik Berlin Subcontractor: Hamburger Sternwarte

13. Thank you for your attention!

14. Price (incl. VAT): • Telescope 1 030 000 € • Dome automatization 53 500 € • Spectrograph 480 000 € • CCD camera 340 000 € • IR CCD camera 590 000 € • Coating unit for the 130 cm mirror 280 000 € • Fiber optic cable from Poprad 124 000 € • Data storage devices 36 000 € • Diesel-electric generator 15 000 € • ∑ 2 948 500 € • Sponsored by: • European Regional Development Fund, 100%