Windowing and Binning

On the red side, windowing and binning are independant, and you can set the pane (window) parameters to pixel values 0-4096. The pane xy values are always expressed in units of unbinned pixels.

On the blue side, windowing and binning are dependant. When operated without binning (binning factor of 1x1) the maximum value for xy windows is 2048. When the binning factor is N, then the maximum value is reduced to 2048/N. Binning by powers of 2 is essential to success, and if binning is changed, you must window the ccd to the corresponding size. You cannot window the blue mosaic across the two CCDs. To window a section, you will have to window on one of the CCDs. See the windowb section below for details on how to do this.

1. The CCD... subwidgets available from the XPOSE GUIS on the red and blue side have functions that alter the windowing and binning.
   On the Blue side
   • Binning 1x2 - bins only in the spectral direction. This will also reset the window appropriately. Decreases the readout time.
   • Binning 2x2 - bins in both spectral and spatial directions. This will also reset the window appropriately. Decreases the readout time, but adds an image artifact.
   • Window full frame mosaic (1x1) - resets to binning 1x1 and full frame mosaic (re-windows to full frame).
   • Two amp readout on blue CCD0 (left) - selects only the left most CCD
   • Two amp readout on blue CCD1 (right) - selects only the right most CCD
   On the Red side:
   • Window CCD 4096x4096 norm 1x1 - full frame readout 1x1 binning.
   • Window CCD to image Area norm 1x1 - windowed to the imaging FOV with 1x1 binning. slightly faster than full frame readout.
   • Window CCD longslit - window the ccd to longslit area. Inst
   • Bin 1x1 normal ccd speed - changes binning to 1x1. Windowing parameter are not changed.
   • Bin 1x2 (spectral) normal ccd speed -changes binning to 1x2 to bin in the spectral direction. Windowing parameter are not changed. Decreases the readout time.
   • Bin 2x1 (spatial) normal ccd speed -changes binning to 2x1 to bin in the spatial direction. Windowing parameter are not changed. Decreases the readout time.
   • Bin 2x2 (both) normal ccd speed -changes binning to 2x2 to bin in both the spectral and spatial directions. Windowing parameter are not changed. Decreases the readout time.
3. Blue side windowing: windowb is a script that may be used to window the blue side. The script is called windowb and takes four arguments (x, y, w, h). The x and y are the starting pixel and the w and h are the width and height of the desired readout region. You cannot window across the two chips, and the script will complain if the desired window spans both chips.

    windowb xpix ypix width height

4. Red Side Windowing: The windowr script is used to window the ccd by setting the appropriate PANE keywords. This does not effect binning.

    windowr xstart ystart width height 

   .
5. The WIN... subwidgets available from the XPOSE GUIs on the red and blue side allow manipulation of the CCD readout window and binning. The blue side may not be windowed, unless the readout is for a single chip. To bin data on the blue side, "Two amp readout" on the left or right must first be selected. If you try to sub_window the blue side or you try binning without setting "Two amp readout," the blue side crate will be lost after the first readout and will require rebooting. See XPOSE for more information.

Speed Test Results

Blue Channel
• 54s - Window Full Frame & 1x1 binning.
• 54s - Windowed in the spatial direction only (100 pix width) & 1x1 binning
• 36s - Window Full Frame & 1x2 binning
• 23s - Window 1/2 Frame & 1x2 binning