RTT150 Telescope

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RTT150 TELESCOPE:

RTT 150 telescope which is the biggest telescope in Turkey, is installed in 1998 under the agreement between Russia and Turkey and the first light was received from the telescope in September 2001. The members of the telescope are TÜBİTAK, Kazan Government University and Russian Space Research Institute. RTT 150 is a telescope which was made by LOMO factory in St. Petersburg and has a pair in Uzbekistan, has Ritchey-Chrétien optical system and can work on Cassegrain and Coude focal plane.

RTT150 – General Specifications:

Mount Type: 

 Equatorial

Tube Length: 

 4970 mm

Weight: 

 37 ton

Mirror Diameter: 

 1500 mm

Mirror Center Hole Diameter: 

 580 mm

Mirror Focal Ratio: 

 f/1.3

Mirror Weight: 

 970 kg

Mirror Width: 

 24 cm

Mirror Holder Weight: 

 2460 kg

Mirror Coated: 

 Al + SiO2

Dome: 
Diameter: 
Gap: 

 Observa-DOME
 10.5 m. (Out)
 3.35 m.

The current set – up of the telescope allows to use on f/7.7 Cassegrain (imaging / spectrum) focus and f/48 Coude (spectrum) focus. But the automation works of the telescope are still going on.

 

Focus

Focal Ratio

Focal Length
(mm)

Focal Scale
("/mm)

Angular Field of View
(')

Linear Field of View
(mm)

Cassegrain

f/7.7

11611

17.8

26.7

90

Coude

f/48

72257

2.9

3.83

80

Photoelectric Tracking Telescope

f/10

3590

57

76

80

Visual Tracking Telescope

f/10

3590

57

76

80

Searcher (2 number)

f/4.2

504

409

240

-

 

TFOSC TUG Faint Object Spectrograph and Camera 

This instrument was made by Copenhag University Observatory (CUO) for Tubitak National Observatory (TUG) under the agreement which was signed in 20 April 2001 and delivered to TUG in November 2004. Because of limited observation time of TUG on RTT150 and the unsuitable weather conditions in winter, the test observations were started in 8 April 2005.

At the TFOSC’s first light night, a gama beam explosion was observed and at the same night a circular was published (GCN 3198).

TFOSC is 10th of the FOSC series which was produced by CUO.

Basic Specifications:

These instruments are “Focus Reduction Multiplier” instruments. This means that effective focal length can be reduced by using a camera and collimator which has same focal ratio with telescope. This has two basic advantages:

  1. With a given receiver, wider space can be comprised.
  2. Spreader elements can be placed between camera and collimator. Thus, the instrument can be used directly as a imager and spectrograph. Rotating the wheel by bringing a grism in front of a parallel beam, from one state to another can be passed within 20 – 30 second. In spectrography, with normal grism, between 200 and 2500 resolution can be achieved but, with “echelle” grism 4500 resolution can be achieved.

Optic:

These instruments are basically two types. In one of them, the beam bends 100°, in other instruments, the optical path is correct line. Only two of FOSC series’ optical path is correct line.

Mechanic:

There is a optic bench where collimator and camera are connected. In addition, 3 wheels are connected to this bench:

On the focal plane, there is a gap wheel in front of the collimator. Between collimator and camera, there are a filter wheel and a grism wheel in front of the parallel beam. Between the last two wheels, there is a rotating shutter. The camera can be rotated around the instruments’ connecting flange. The outer circle of the three wheels is geared and can be rotated by a step motor with a smaller gear.

Electronic:

Rotating the three wheels and motion of the camera and the cover are controlled by individual step motors. Each function is controlled by separate and same electronic cards. These electronic cards are connected together via serial port (RS – 232) and managed by a PC. Optic design requires 30x30mm CCD.

Specifications:

RTT150 consists of two pieces which one of them is TFOSC Cassegrain Spectrograph and another is Filter and Calibration Unit. TFOSC’s reduction factor is 0.68 and its optic similar to HFOSC which is last instrument made for India. These instruments’ mechanic design and electronic are made by CUO, their optical design and production of the parts were made by Swedish FISBA firm and their optical network is made by Richardson Grating Lab. Combining of the all parts and attaching to RTT150 were made by CUO.

This spectrograph has two functions: a) Imaging directly      b) Low/mid resolution spectography

Some specifications and parts of TFOSC are given below:

  1. Wavelength Range: 330 – 1200 nm
  2. Focus Reduction Ratio: 0.68
  3. Image view: 13.3’ x 13.3’
  4. Spectrograph Resolution: R 200 – 5000 (with normal and echelle grisms)
  5. Optical part where Collimator and CCD Camera are placed
  6. 2 number 5 – slot filters wheel called FASUA and FASUB
  7. 8 – slot gap wheel
  8. 8 – slot filter wheel
  9. 8 – slot grism wheel
  10. 6 large gaps (39,44,54,67,100 and 134 micron)
  11. Using standard PC (Linux operating system)
  12. Control Program with Graphic User Interface (GUI) made by IDL
  13. Supported Remote Control Specifications:
  • Positioning gap wheel
  • Positioning filter wheel
  • Positioning grism wheel
  • Controlling spectrum lamps
  • Controlling CCD Camera
  • Focusing CCD Camera

Filter And Calibration Unit: (CAU: Calibration Unit)

This Unit in TFOSC consists of:

  1. 5 – Slot Filter wheels called FASUA and FASUB. Between 51 – 60 mm circular or 50 x 50mm quadratic filters can be attachec to these wheels. The beams come from telescope through the filters are not parallel.
  2. 6 lamps (Halogen, Ne, He, Fe – Ar and Th – Ar) and transfer optics for spectrum calibration.

Usable Optical Networks:

Grism

Order

Number of Expansion

Resolution

Wavelength Range (A)

Delta Lambda

Region

 

 

 

 

 

 

 

7

1

107

1331

4300-6250

4.1

Visual

8

1

88

2189

6200-7850

3.0

Red

 

 

 

 

 

 

 

9

6-18

25

5099

3350-9400

1.2

Echelle

 

 

 

 

 

 

 

10

1

456

228

3300-6400

17.0

blue,  cross spreader

11

1

341

392

4000-7600

13.0

visual,  cross spreader

12

1

913

205

5300-10200

37.0

red, cross spreader

 

 

 

 

 

 

 

14

2

94

1337

3270-6120

5.4

blue,  better than 6

15

2

211

749

3230-9120

12.0

Blue-visual,  by cross spreader 330-910nm range

17

2

93

2659

6500-12000

 

red (8’s red)

 

Available Gaps:

The CCD used in TFOSC has Fairchild 447 chip type with backlight. CCD Camera is cooled by liquid azote (nitrogen).

Pixel Format: 

 2048 x 2048 pixel

Pixel Sizes: 

 15 x 15 μm

Piksel Scale: 

 0,39 "/pixel

Image View: 

 13,3' x 13.3'

Gain: 

 1.34 e-/ADU (High, Amp. A)

 5.02 e-/ADU (Low, Amp. A)

 

 1.35 e-/ADU (High, Amp. B)

 5.06 e-/ADU (Low, Amp. B)

Reading Noise: 

 5.1 e-(High gain, Amp. A)

 7.6 e- (Low gain, Amp. A)

 

 5.3 e- (High gain, Amp. B)

 7.8 e- (Low gain, Amp. B)

 

Filters:

60mm diameter circular or 50 x 50mm quadratic filters can be used in TFOSC. For specifications of available filters, please click:

Brightness Limits and Exposure Times:

According to test observations, to investigate the reached brightness, exposure times and error limits, please click:

Spectrum Lamps:

Lamp Type

Vendor Firm

Lamp Code

Central Wavelength

Halogen

OSRAM

Halostar-64415 (12 V, 10 W)

-

He

OSRAM

He/10 (60 V, 55 W)

-

Ne

OSRAM

Ne/10 (30 V, 30 W)

-

Fe-Ar

PHOTRON

P826

248,3 nm

Fe-Ar

Säntis Analytical

SAP826

248.3 nm

Th-Ar

Säntis Analytical

SAP858

371.9 nm

  

Halogen: For flat area

He: For calibration wavelength

Ne: For calibration wavelength

Fe – Ar: For calibration wavelength

Th – Ar: For calibration wavelength

 

Andor CCD Kamera:

On RTT150 Telescope, Andor CCD Camera used on Cassegrain focus is the best resolution camera in Astrometry observations. When this camera is attached, the tracking correction of RTT150 is achieved by AP47 CCD Camera which is placed in the same chassis. Andor CCD has two filter wheels and each wheels have 8 – slot. In these wheels, there are Bessel UBVRI and SDSS filters. The images received by Thermoelectric cooled Andor CCD are transferred to PC by Andor MCD software through an electronic card.

Specifications of Andor CCD Camera:

Model: 

 Andor DW436, with backlight

Format: 

 2048 x 2048 pixel

Pixel Size: 

 13.5 x 13.5 micron

Chip Size: 

 27.6 x 27.6 mm (761 mm2)

Pixel Scale: 

 0.24"/pixel

Image Field: 

 8.2' x 8.2'

Well: 

 80,000 e-

Digital Resolution: 

 16-Bit (1 MHz)

Dark Current: 

 0.01 e-/pixel/s (-60 Cº)

Reading Noise: 

 3.5 e-(31 KHz)

Gain: 

 1.4 e-/ADU

Binning: 

 1x1 - 64x64

Cooling: 

 2 stage TE + air, between 20 Cº and -60 Cº

PC Interface: 

 CCI-010 PCI Control Card

Software: 

 Andor-MCD Software

Filter Wheel: 

 50x50 mm, 8 slot

Filters: 

 UBVRI

 

Andor DW436 CCD Technical Information (Eng.) --> Click

Andor iXon+ EMCCD Kamera: 

On RTT150 telescope, Andor iXon used on Cassegrain Focus for high speed imaging became one of the RTT150’s focus imager in 2009. Unlike other Andor DW436 CCD camera model, this camera is able to receive 9 images per second. But, if small areas are selected, 300 images can be received per second.  

By this high speed CCD, high speed photometry applications could be done. Therefore, the researchers should prepare observation projects by paying attention to technical details which is given below.

Specifications of Andor iXon CCD Camera:

Model: 

 Andor iXonEM+ CCD, with backlight

Format: 

 1024 x 1024 pixel

Pixel Size: 

 13 x 13 micron

Chip Size: 

 13.3 x 13.3 mm

Pixel Scale: 

 0.23"/pixel

Image Field: 

 3.9' x 3.9'

Well: 

 80,000 e-

Digital Resolution: 

 16-bit (1 MHz), 14-bit (10, 5, 3 MHz)

Dark Current: 

 0.010 e-/piksel/sn (-75 Cº)

Reading Noise: 

 <1-47 e-(10 MHz)

Gain: 

 1-1000 (Electron Multiplier)

Binning: 

 1x1 - 8x8

Cooling: 

 TE + air, between 20 Cº and -80 Cº

PC Interface: 

 CCI-23 PCI Control Card

Software: 

 Andor-Solis

Filter Wheel: 

  50x50 mm, 8 – Slot

Filters: 

 UBVRI, SDSS

 

Fast Photometry Technique with Andor iXon EM CCD:

By using technical specifications of Andor iXon EM CCD, the observation projects which require fast photometry could be done on RTT150. The researchers who study fast photometry required projects could prepare their project requests in accordance with the informations which are given below.

By this CCD, 8 images could be received in 1024 x 1024 pixel format (full frame).

For high time resolution requiring projects, 300 images could be received per second by using electron multiplying + subframe specifications of the camera. In electron multiplying specification, unlike used binning in classical CCD, each pixels which create each column of the selected area are collected. As a result, the obtained result is like a one – dimensional strip. For example, if “1024 x 60” pixel size will be examined, “X1=1, X2=1024 Y1=1, Y2=60” standart for subframe and “XBIN=1, YBIN=60” for electron multiplying could be selected. In this instance, the obtained results would be “1024 x 1” format size. The procedures are showed as representation below:

100 is a good choice for CCD gain.

Depending on exposure time, the camera software shows how many “strip/frame” could be received per second. 

For “one – dimensional strip” technique requiring studies, in the event of the comparison and  star that changed dropping to same frame, the line that combines should be adjusted to be parallel to horizontal edge of CCD.

The studies, which are done by Andor iXon EM CCD and the given software below, must remark as "TÜBİTAK Research Project (Project No:209T055)" in addition to “TUG support”.

Coude + Andor CCD (2003):

On RTT150 Telescope, 1K x 1K SAO RAS CCD used on Coude focus was sent back to Russia in June 2009 because of its fault in May 2009. On June 2009, 2K x 2K Andor CCD was started to use as Coude Camera for spectroscopic observations. Comparing to previous camera, the Andor CCD camera covers wider spectroscopic range and also has better SNR (signal noise ratio) value.

Technical informations for spectroscopic observations were given below:

Specifications of Coude and Andor CCD Camera:

Brightness Range 

 3m-9m

Std. Exposure Times 

 300, 600, 900, 1200,1800, 2700 s

CCD Cooling Value 

 -60 C°

Spectral Order 

 85

Bias  

 10 poses in the morning and evening

Flat (Halogen) 

 In the morning, 10 poses, 2-3 s exposure time
 (25000-40000 ADU)

Flat (Th-Ar) 

 In the morning, 3 poses, 300 s exposure time

 

DEFPOS - Dual Etalon Fabry Perot Optical Spectrometer

TUG H – Alpha Spectrometer was designed to observe the selected region of northern hemisphere and and H – Alpha. Spectrometer Bakirlitepe was designed to use on Coude Focus System of RTT150 which is located in Antalya. Double Etalon 7.5cm Fabry – Perot spectrometer samples sphere 4 arc minutes in main spectral model. The spectral resolving power is about 20km.

The Spectrometer was designed in cooperation with Cukurova University Physics Department, Adana, METU Physics Department, Sabancı University Astrophysics and Space Programme, Istanbul, TUBITAK National Observatory and TUBITAK.