Operation of the Steward Observatory 61" Kuiper Telescope CCD Guiding System (BigGuider)


  1. Introduction and Acknowledgments.
  2. Basic information about the CCD guider dewar and detector (BigGuider).
  3. Observer and Instrument safety (in case you need assistance...).
    • Contact List
  4. BigGuider Startup.
  5. Guider Operations and the Control GUI.
  6. Moving the Guider Probe to Find a Guide Star.
    • Limits on the Motion of the Guider Probe
  7. Shutting down BigGuider.

1. Introduction and Acknowledgments.

Back to the top of the document.

2. Basic Information About BigGuider.

  • Device: MIT/LL CCID-37
  • Device Names: BigGuider SN4134
  • Device Size: 512 x 512 (15 x 15 micron pixels)
  • Image Scale: 0.29 arcsec/pixel
  • Field of View: 2.5 arcmin x 2.5 arcmin
  • Gain: 2.3 electrons/ADU
  • Readout Noise: 13.7 electrons
  • Dark Current: 126 electrons/pixel/sec
  • Full Well: 103,000 electrons unbinned
  • Operating Temperature: ~ -50 C
  • Filters: Currently unfiltered

Back to the top of the document.

3. Observer and Instrument Safety (In case you need assistance...).

In case of problems with BigGuider:

    Please report any problems encountered with BigGuider in that night's Trouble Report. Be as detailed as possible. It may also help in diagnosing problems if relevant guider CCD images are saved and identified so that they can be found and examined by support/technical personnel.

Back to the top of the document.

4. BigGuider Startup.

At the south side of the guider box:

  • Turn on the power to the BigGuider CCD controller. The dark blue controller is mounted located on the south side of the guider box if the instrument is mounted to the telescope in the usual (default) fashion.
  • Turn on the cooling unit. It is located on the west side of the guider box. The toggle switch must be pulled out in order to be toggled. A green light on the cooling unit will show when the red button is pushed in if the cooling fluid is being adequately circulated to the guider CCD dewar.
  • Power on the guider x-y stage. The switch is located on the south side of the guider box and is west of the CCD guider controller. This switch also powers on the filter wheel of Mont4K.

In the control room:

  • With the bigag PC booted, click on the "TELCOM150 Server" and "Start BigGuider" icons (in that order).
  • Once the camera is automatically initialized and ready for use, one may set parameters, take pictures, guide, etc.
  • On the kuiper computer, startup the filter wheel GUI (this step is part of the normal startup procedure of Mont4K). This GUI includes control of the guider x-y stage. With this GUI, you can move the guider pickoff mirror around to locate guide suitable guide stars. Be advised that currently there are NO hard limits imposed on the motion of the x-y stage that would prevent the stage/pickoff mirror from vignetting the field of view of the science detector. See below for a listing of x-y stage encoder values that safely keep the guider mechanism from interfering with your science exposures.

Back to the top of the document.

5. Guider Operations and the Control GUI.

    The BigGuider control GUI is pictured below (the large window at the left of the screenshot) and runs on the bigag PC. Please note that this example screenshot was taken when the CCD guider was being used with the SPOL spectropolarimeter. There will be no slit visible in the guider's field of view when the system is used at the Kuiper Telescope.

    • In the lower right corner of the GUI, 4 large buttons allow you to take a single or repeated exposures with the guider CCD, or start a guiding sequence (either full frame or within the smaller guider window denoted by the white square overlayed on the field of view.

    • The exposure time can be set using the vertical slide bar to the left of "Acquire" and "Guiding" buttons, or by typing the desired exposure time within the box above the slide bar. Exposures can be as short as 0.1s. The exposure time can be adjusted without stopping an exposure or guiding sequence.

    • Clicking on the desired star in the field will center the guiding box on the star. The size of the guiding box can be adjusted using the horizontal slide bar in the lower left corner of the GUI. Make sure to leave some sky around the guide star so that the background can be properly determined within the guiding algorithm.

    • Messages from the guider to the telescope or to you are highlighted in red and displayed below the guider window size slider.

    • The guiding centroid position can be adjusted using the 'L'eft, 'R'ight, 'U'p, and 'D'own buttons. The number displayed in the center of these bottons is the number of pixels that the guiding window will be moved for each click on a button (this number can be changed via the "Edit guiding parameters" option in the "Parameters" menu). This adjustment of positioning can be made while guiding is in progress.

    • Before guiding can commence, the guider needs to know which way is north and east and the pixel scale. This information is supplied to the guider by doing an x-y transformation (found in the "Telescope" menu). The task steps the telescope through a series of moves. The observer is prompted to click on a chosen star after each move. This step is only needed once as long as the guider box is not rotated on the telescope. Once the tranformation is complete, the image will display a compass and the centroiding and image information given along the right edge of the GUI will be correct. It is recommended that you do a transformation at the beginning of your observing run or after the instrument has been rotated on the telescope.

    • While guiding, stripcharts that track the guiding corrections in RA and Dec, the FWHM of the guide star, and the guide star flux can be displayed. The tracking charts are shown in the example screenshot on the right side of the screen. This option needs to be chosen, if desired, before a guiding sequence is started and is very useful if one wants to track guiding performance, seeing/focus, and whether it is truly photometric. Once the stripchart window has been selected, it will be operational until it is closed (i.e., one does not need to bring up a new stripchart window at the start of a new guiding sequence). The charts are displayed be default, but can also be selected from the "Display" menu.

    • Crosshairs can manually be placed or erased on the image display. See the "Display" menu to create or destroy markers.

    • The guider can be used to offset the telescope if desired and if an x-y transformation has been performed. Entering the "Telescope" menu (this menu can be reached from going to the top edge of the GUI, or by using the right mouse button while within the image frame) and selecting "Telescope Offset", one can then click on a position within the image frame and then click on a position within the frame that you like to move the originally chosen position. Alternatively, offsets in RA and/or Dec can be entered in the appropriate boxes within the "Offset Telescope" popup window to move the telescope the desired amount and direction.

    • Many other options are available within the BigGuider GUI. Explore the menus to see if any will be useful for your observing program.

Back to the top of the document.

6. Moving the Guider Probe to Find a Guide Star.

The GUI contolling the positioning of the x-y stage that allows the pickoff mirror to be moved around within the focal plane can be accessed on the kuiper computer (start the galilserver and filter wheel GUI). The guider probe can be moved to find a suitable guide star for the science field. Currently, there are no motion limits or warnings given that alert the observer if the probe vignettes the science field of view. However, the effect on the Mont4K field of view has been mapped and observers should avoid the regions outside of those listed below if an unvignetted science image is desired.

The following x-y stage encoder values avoid vignetting the Mont4K FOV and excessive vignetting of the guider FOV:

  • When -1000 > Y > -3400, X can range from -1000 to -14000 (the guider probe is NORTH of the science FOV).
  • When -3400 > Y > -12100, X MUST be in the range from -1000 to -3000 (the guider probe is WEST of the science FOV).
  • When -12100 > Y > -15000, X can range from -1000 to -14000 (the guider probe is SOUTH of the science FOV).

Hitting the "Center" button on the control GUI will place the probe close to the center of the Mont4K field of view and block most of the field.

"Homing" the stage places it at 0, 0; well out of the Mont4K field of view, but not within a range where guide stars can be seen.

A move of 500 units in either axis of the guider stage moves the guider field of view by about 1 arcmin.

Back to the top of the document.

7. Shutting down BigGuider.

It is IMPORTANT to shut down BigGuider in the case of threatening weather.

In the control room:

  • Shut down the autoguider GUI from the "File" menu or from the popup menu displayed when clicking the right mouse botton.
  • Close out any associated guider windows that the GUI shut down misses.

At the south side of the guider box:

  • Turn off the power to the BigGuider CCD controller.
  • Turn off the cooling unit. The toggle switch must be pulled out in order to be toggled.
  • Power off the guider x-y stage. The switch. Note that this will also power off the Mont4K filter wheel.

Back to the top of the document.

Back to the Mont4K Manual.
Back to the 61" Operations Manual.

Back to the 61" Home Page.

The 61" cognizant observer is Paul Smith --psmith@as.arizona.edu