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Simple Preset
SUSI_img_acq_Preset

• points the telescope to the required field
• moves the rotator to the desired position angle
• aquires a guidestar

If you wish to track a moving object, you should add the appropriate rates into the fields: Differential Tracking in RA and Differential Tracking in DEC .

P2PP panel with typical parameters

The above example shows a simple preset template to put the rotator to 90 degrees, and track the target.

Move to Pixel
SUSI_img_acq_MoveToPixel

Binning: 
This is set with the field CCD X binning. You can change the default value of 2 to 1 (for 1x1 binning), 3 (for 3x3 binning) or 4 (for 4x4 binning). Note: Only 1x1 and 2x2 binning are officially supported. You use 3x3 and 4x4 binning at your own risk.

Windowing: 
Windowing of the CCD is controlled through 5 parameters:

• CCD Windowing Flag
• First column of window
• First row of window
• Number of columns
• Number of rows

P2PP panel with typical parameters

If do wish to window the CCD, make sure that the CCD Windowing Flag is checked. You must then enter the start pixel in X and Y respectively in the First column of window and First row of window fields. Then you must define how large you wish your image to be in the Number of columns and Number of Rows fields. NOTE: Entries for First column of window, First row of window, Number of columns and Number of Rows MUST BE THE NUMBERS YOU WOULD SELECT IF BINNING 1X1. Even if your exposures are actually binned 2x2.

P2PP panel with typical parameters
In this example, we are windowing the CCD (CCD Windowing Flag is checked). Our window starts at pixel (500,500), and is 1000x1000 pixels in size (i.e. last pixel will be 1500,1500). NOTE: These pixel values would be correct IF we were binning 1x1. Although we must define these parameters as if we were using 1x1 binning mode, we are actually using 2x2 binning (see CCD X binning field) and therefore our pixels will run from (250,250) to (750,750).

Now for the rest of the OB: 
There are two ways of moving your object onto the particular pixel you desire:

1. Predefining the reference pixel in the OB. This invokes the following steps:
• points the telescope to the required field
• sets the rotator at the desired rotator angle
• puts the correct filter in the beam
• aquires a guidestar
• takes an exposure with Exposure time seconds
• reads out the CCD and transfers the data
• a popup window then asks you to click on the object you would like to place on the reference pixel, using either a centroid or the cursor.
  This must be clearly indicated on the finder chart for SM observations
• you may then select to do one of the following:
  • perform the offset and take another image to check the new positioning
  • perform the offset and move onto the science exposures (i.e. you trust the offset and are not too worried about exact positioning)
  • do not perform the offset and move onto the science exposures (i.e. the star will remain where it is in the aquisition image)
  • abort the OB
  What you choose will depend on exactly how precise you want the positioning to be. Usually the initial offset (first iteration) will put the star within ?? pixels of the requested pixel coordinates. Subsequent iterations will get it within a few pixels, but the chances of it actually falling exactly on the same pixel are not high.

One should allow ~1 minute + exposure time for each iteration.

P2PP panel with typical parameters

The above example shows an acquisition template to preset the telescope, set the rotator at 0 degrees, put the B#811 filter in the beam, start the autoguider and take an unwindowed, 10 second acquisition image with 2x2 binning. Note: the Click on Target Pixel Coordinates flag is not checked, which means that the coordinates Target Pixel Coordinates if CLICK.PIX is False will be used for the reference pixel (in this case: 2250, 2048). NOTE: the values in Target Pixel Coordinates if CLICK.PIX is False must correspond to the values for 1x1 binning, even if you are using 2x2 binning. Selection of the object to be placed on the reference pixel is done interactively on the RTD following instructions in a pop-up window.

2. Selecting the reference pixel and the object interactively on the RTD. This invokes the following steps:
• points the telescope to the required field
• sets the rotator at the desired rotator angle
• puts the correct filter in the beam
• aquires a guidestar
• takes an exposure with Exposure time seconds
• reads out the CCD and transfers the data
• a popup window then asks you to click on the reference pixel where you would like to place your object.
  This must be clearly indicated on the finder chart for SM observations
• a second popup window then asks you to click on the object you would like to place on the reference pixel, using either a centroid or the cursor.
  This must be clearly indicated on the finder chart for SM observations
• you may then select to do one of the following:
  • perform the offset and take another image to check the new positioning
  • perform the offset and move onto the science exposures (i.e. you trust the offset and are not too worried about exact positioning)
  • do not perform the offset and move onto the science exposures (i.e. the star will remain where it is in the aquisition image)
  • abort the OB
  What you choose will depend on exactly how precise you want the positioning to be. Usually the initial offset (first iteration) will put the star within ?? pixels of the requested pixel coordinates. Subsequent iterations will get it within a few pixels, but the chances of it actually falling exactly on the same pixel are not high.

One should allow ~1 minute + exposure time for each iteration.

P2PP panel with typical parameters

The above example is exactly the same as before, except that now the Click on Target Pixel Coordinates flag is checked. Therefore, the coordinates in Target Pixel Coordinates if CLICK.PIX is False are ignored, and the coordinates of the reference pixel will be chosen interactively with the RTD. The object to be placed at the reference pixel is also done interactively on the RTD following instructions in a second pop-up window.

Send comments to : ls-susi Last modified: Wed Nov 05 2003