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15 Νοε 2013 (πριν από 3 χρόνια και 6 μήνες)

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PROJECT OF THE 130 cm

TELESCOPE


FOR THE

SKALNATÉ PLES
O

OBSERVATORY

Jozef Žižňovský Stakčín, December 2012


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

a
nd

a
meteosta
tion
.


In principle it is a

robotic

telescope
.


Manufacturer and supplier:
ASTELCO
Systems

GmbH
,
München


Instruments in the foci
:


CCD
camera for near UV, visual and red spectral region

IR CCD
c
amera

for

infra
red region


Echelle

spektrogra
ph



It will be provided

in the frame of the European

Regional Development

Fu
nd


in

t
h
r
ee

steps
:


1.
Telescope: till the end of

2013

2.
Dome
computerisation

: 2013

3.
Focal instruments

a
nd

infra
s
tru
c
t
u
r
e
:
Spring

2014



Main mirror M1,
free aperture


~ 1 300mm

Main mirror M1,
mechanical diameter


~ 1 310mm

Main mirror M1, focal ratio

F/2.8 *

System focal ratio

F/8

Wave front error





⼶/慴‶㌳湭n前R

䙩敬搠潦eV楥i 慴a
乡獭y瑨

景捵f


> 0.5 deg

Mirror material

Zero Expansion Glass

(
Zerodur


or
Astro

Sitall
)

Mirror coating

Al (Aluminium) + protection layer

Mirror reflectivity

R > 94%

1.
TELESCOPE

1.1. Opti
cs



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.


2. Mechanics

2.1 Dimensions



Maximum height (tube in vertical position)*


440 cm**

Minimum height (tubus in horizontal position)*

300 cm**

Optical tube lengths


300 cm**

Maximum radius of movement (horizontal position)

215 cm**

Required concrete foundation diameter


300 cm**

Total weight of the telescope in basic specification

~ 7 t

*
Calculated from the lower surface of the telescope basis


**

Dimensions after the preliminary design phase



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.


M1

M2

M3


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 corrected

by the software.


Slewing speed* 20
°
/sec

20
°
/sec

Absolute pointing accuracy


< 5 arcsec RMS


Differential pointing accuracy


< 0.2 arcsec RMS


Tracking accuracy without
autoguider


< 0.5 arcsec/10 min


Tracking accuracy with
autoguider


< 0.25 arcsec/10 min


Effective encoder resolution


328 increments per arc sec
(0.003 arc sec / increment)



FOCAL INSTRUMENTS

1.
CCD camera for near UV to red spectral region



Quantum efficiency

in 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

⽰楸i氯獥c



Readout noise: less than 5e
-

(rms)



16 bit AD converter


C
o
oling with cryotiger to

<
-
100
°

C


Example: Spectral Instruments

1110S


http://www.specinst.com/Brochures%20Rev%20A/1100S
-
camera
-
broch_RevA.pdf



2
.
IR CCD camera for near infrared region



Quantum efficiency

in the interval of

900
-
2 300nm: 70%



Sensor size

2k x 2k, HgCdTe

technology, class 1





Pixel size: 15 µm



Dark current maximum: 0.01e
-

/pixel/sec



Readout noise: less than

20e
-

(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
H
ubble
S
pace
T
elescope

and

the
J
ames
W
ebb
S
pace
T
elescope
)



http://www.teledyne
-
si.com/infrared_visible_fpas/index.html


3. Spe
c
trogra
ph

Hihg
-
dispersion

échelle spectrograph to the Nasmyth focus
:




R = 40 000

for seeing 3"




S
pectral region: 400
-
760nm




CCD
c
amera

2k x 2k



Calibration lamps for ThAr line spectrum and continuum light



Interchangeable slits

(apertures)




S
oftware for remote control of
the
spectrograph and
its
CCD camera

Manufacturer, contractor: Lasertechnik Berlin


Subcontractor: Hamburger Sternwarte

Thank you for your attention!


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,



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