TV-Guider User´s Manual

Contents

  1. General Introduction
    1. Basics
    2. Monitors and Windows
    3. Camera-Configuration at
      1. 3.5m Telescope
      2. 2.2m Telescope
      3. 1.23m Telescope
  2. How to login, start, finish ...
  3. Usage of the cameras
    1. Adjusting the cameras
    2. Shutter and Overload
  4. How to grab images
  5. Working with images
  6. The Autoguider
  7. Focussing the camera
  8. Some more commands you must know
  9. Some more remarks you should read (e.g. trouble shooting)
  10. Scales and Sizes
  11. Appendix

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General Introduction

Basics

The TV-Guiding-System at each telescope consists in principal of two components:

  1. The Cameras: Proxitronic Cameras (HL-A/MPIA-Version), consisting of
    1. MCP-proxifier as first stage, (S-25-Cathode)
    2. an inverting image intensifier as second stage for size-adaption to the CCD and
    3. a PULNIX TM860 (CCIR) CCD-Camera with 774 x 574 pixel of 11/11.5 micron
    The MCP-Gain and the Video-Gain are controlled by an external voltage.
  2. The Control Computer is a HP-486/25 MHz EISA PC, running under a standard System-V-UNIX Operating System with X11 Release 5 and OSF Motif as Graphical User Interface (GUI).
    Hence capitalization and use of small letters is strictly distinguished.

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Monitors and Windows

The TV-Guider-System uses two monitors:

  1. The Video Display Monitor shows the TV-camera images and related informations.

    videoDisplay.Image
    Video Display in Slit-view mode with TWIN spectrograph.
     Click on the image for a more detailed view.

  2. The Control Monitor is used for operating the TV-Guider. For this, two basic windows are opened, the
  3. Note: The Cursor has to be moved to the window you want to work in, - especially for using the Function-keys and the ESC-key, the Cursor must be in the Command Shell Window.
    More windows are opened on request, e.g. for Aperture, Filter list, etc.

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Camera Configurations

The Configuration at the 3.5m telescope:

One of the following 5 configurations has to be selected at startup of the TV-Guider program:

  1. Cassegrain Imaging (Mode: Acquisition, Guiding)
  2. Cassegrain Spectroscopy (Mode: Acquisition, Guiding, Slit-view)
  3. Prime-focus/K2 (Mode: Acquisition, Guiding)
  4. Prime-focus/K3 (Mode: Guiding)
  5. Cassegrain Adaptive Optics
Cassegrain imaging:
Cassegrain Imaging is used with all imaging-like instrumentation (e.g. MAGIC, etc.) for Acquisition (on-axis field) and Guiding (Off-axis field).
Camera-Options: 3 filter and focus.
Cassegrain spectroscopy:
For Cas Spectroscopy, (TWIN-spectrograph, MOSCA, Spaltspinne, FOCES, etc.) a slit-view is supplied in addition to the Cass Imaging mode.
Camera-Options: 3 filter and focus.
Prime-focus/K2:
In the Prime-focus/K2 one single camera serves Camera-Options: 2 filter, aperture, and focus.
Prime-focus/K3:
In the Prime-focus/K3 a single camera serves only for guiding.
Camera-Options: 3 filter and focus.
Cass Adaptive Optics (ALFA):
This camera is part of the ALFA instrumentation. It's usage is described in the ALFA manual.
Camera-Options: 3 filter and focus.

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The Configurations at the 2.2m telescope:

At the 2.2 one of three configurations has to be chosen at start of the program:

  1. Cas Imaging with camera modes Acquisition and Off-axis Guiding
  2. Cas Spectroscopy with camera modes Acquisition, Off-axis Guiding and Slit-view
  3. Coude with camera mode Slit-view.

In configuration Imaging you can use the TV-Guider for Acquisition (On-axis camera) and for Guiding (Off-axis camera). To enhance the accessible field for finding a guide star the Off-axis camera can be moved in one direction (slider Guide field). If you are working with the Cassegrain spectrograph (Configuration Spectroscopy) the On-axis camera serves for Slit-view, too. The Slit-view mode can be used both for Acquisition and Guiding. At the Coude focus only one camera is installed, looking on the slit.
Camera-Options
- Cas On-axis Camera: 3 filter, aperture and focus
- Cas Off-axis Camera: focus and transversal movement (slider Guide field)
- Coude Camera: 3 filter and aperture.

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The Configuration at the 1.23m telescope:

The TV-Guider of the 1.23m telescope (Cassegrain focus) is part of the Instrumentenansatz, which normally is used for CCD direct imaging. Thus the TV-Guider can only be used if that Instrumentenansatz is installed at the telescope. The TV-Guider has only one configuration: it uses a single movable camera for both On-axis (acquisition) and off-axis (guiding) operations, --- thus the camera position (slider Position) has to be set accordingly. The borders of the guiding regions left and right of the on-axis beam depend on the size of the used CCD-detector and will be given to you by the Calar Alto staff. Clicking on TV-Mode/Acquisition or TV-Mode/Guiding will move the camera to the on-axis position (0) or into the beginning of the right guiding region, respectively.
Camera-Options: 3 filter, aperture, and focus.
Note: The camera-focus is automatically adjusted for the difference between on-axis and off-axis positions if you once pressed the button Focus ok!. Yet be sure that you focussed the TV-Camera properly at the present position before initialization of the focus adjustment. Any movement of the focus slider (or entering set -f in the Command shell) stops the automatic adjustment of the focus difference!

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Switching between camera modes

You switch between the different camera-modes of each configuration by a mouse-click on the equivalent command in the menue TV-Mode of the TV-Guider Control Panel. Changing mode/camera needs some activities, so you have to wait for completion of that action. The "Busy"-state is symbolized by a change of the Cursor shape: when "busy", the Cursor looks like a small watch.

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How to login, start, finish ...


Usage of the TV-cameras

Adjusting the camera(s)

All tasks related to selecting or adjusting a camera are performed within the TV-Guider Control Panel. Up to four sliders help you to adjust the parameters of the active camera, i.e. gains (MCP-Gain, Video-Gain, Offset) and, - besides Coude, also focus. If filters are supported, the diamond buttons allow you to select one of the available filters. Clicking with the mouse on menue Info/Filterlist will show you more informations about the filters installed. The iris-diaphragm is closed, opened or stopped by clicking on the equivalent commands in the window that is opened by menue Misc/Aperture
The sliders generally are scaled to 100. Moving the slider is done by mouse, i.e. by dragging it to the goal position or by clicking with the left mouse button, which causes a stepwise moving of the slider. For indication of Busy-state the Cursor shape changes to a small clock. The momentarily disabled functions always are shown slightly shadowed.

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Shutter and Overload

The shutters of the cameras normally open and close automatically when using the image acquisition commands grab, quick and intup. If too much light is seen by the camera, it will go in Overload on followed by a beep and a warning message on the control monitor. The shutter is closed automatically and the Overload status is reset when clicking on Dismiss in the warning window.
Before starting a new image acquisition you first have to prepare for conditions to prevent the camera from going in overload again, e.g. by using a density filter or the iris-diaphragm, or by moving the camera or the telescope, respectively.

Attention: Too much light can cause damage to the camera.
So, be careful where the active camera looks at when you open the shutter by one of the image acquisition commands. The input plane of the camera, which is the input cathode of the intensifier, is the critical element that can be damaged. A very low MCP- and Video-Gain will pretend a sufficient low signal, although the incoming light itself may be already too bright for the cathode. Thus a medium or high MCP- and Video Gain (> 50%) makes sure that the overload mechanism functions properly. When the camera does not go in overload with these gain values there is no problem to reduce the gains further. So, as a good precaution, use grab or intup and start with a high MCP- and Video-Gain (e.g. 70)!

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Grabbing of images

Use intup or grab for an overview.
Use grab or quick when telescope movement has to be watched.

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Working with the images

Video Display-Cursor:
Via the button Video Display in the TV-Guider-Control Panel you have access to the Video Display Cursor on the Video-Monitor. Then a cursor appears on the Video-Screen thus symbolizing that you are now in Video Display CURSOR MODE. Look at the Video-Screen and move the mouse which controls now the Cursor on the Video-Screen. Click the right mouse button to return to the Control Monitor. If there are problems to leave the Video-Display see Troubleshooting .

Note: CURSOR MODE on the Video-Screen partly is available with active grab. It is not available during active quick or intup image acquisition.

In CURSOR MODE the following commands are supported: