Ccds Acquisition Camera User’s Manual

CCDS Acquisition Camera User’s Manual

To place a filter in the beam, find the “Filter” pull-down menu and simply select the filter you desire. The camera will rotate the correct filter in front of the CCD.

If for some reason the items on the pull-down menu are greyed out, select Filter Wheel Setup. Under Filter Wheel select CFW-8. This should display 5 filters on the left hand side of the dialog box. Click OK. You should now be able to select a filter from the pull- down menu.

If you believe for some reason the filter you selected was not in fact the filter that was placed in the beam, select Calibrate/Initialize from the Filter pull-down menu. After a few seconds the filter wheel will be initialized and should no longer be confused about which filter is in the beam.

5. Changing the Integration Time

For very faint targets, some more clever tricks may be needed to acquire your target successfully.

If the stars in your field are very faint, the first thing to try is to turn up the integration time. First stop the focus sequence by pressing the “Focus” button on the toolbar. Start a new focus sequence by pressing the “Focus” button again; type in a longer integration time in the window that appears.

Note that very long integration times (e.g., longer than ~60 seconds) may require dark frame subtraction to deal with the dark current in the device. If you are not worried about the update rate, you may turn on dark frame subtraction by checking the “Dark Frame” box in the Focus pop-up window. This is probably undesirable, however, since the camera will update less than two times less frequently.

Alternatively, you may take one dark frame and apply it to many CCD images. To do this, click on the “Setup” button on the toolbar. Under General, change “Reuse dark frames” to Yes. CCDOps will take one dark frame at the beginning of a focus sequence and reuse it throughout the sequence. If you change integration times, it will take a new dark frame again at the beginning of the sequence. Remember that this step is unnecessary for very short exposure times and will only slow down the readout rate of the CCD.

6. Binning

It is possible to bin the ST-9 chip in 1x1, 2x2, and 3x3 modes. The default is unbinned (1x1). To change the binning factor, go to the Camera pull-down menu and select Setup. In CCDOps-speak, “High Res” means unbinned, “Medium Res” means binned 2x2, and “Low Res” means binned 3x3. You will probably only need to use the unbinned mode.