Note that if the cursor is on the "Set Camera" button, it goes green regardless of the state of the camera settings.

Once a setup is selected and invoked, it can be edited by simply changing the value of any parameter. The new value is automatically saved as part of the current setup. Setups can be named from the 2nd Level.

Because this is a shutterless system, actual exposure time is the number of seconds selected on the slider plus the CCD readout time. Thus, "zero" exposure is actually a minimum integration equal to the CCD read time (about 2 seconds for an unbinned exposure of the whole chip at slow readout, less than 1 second for fast readout). This is generally short enough for all but the brightest stars, or for occasions when an especially high frame rate is desirable.

There are, however, several ways to decrease the readout time and therefore the "minimum" integration. Binning or increasing readout speed (both are options in this window) decrease readout time, but while these approaches can be useful for acquisition, they should not be used for guiding as they decrease resolution, change plate scale, or cause aberrations.

The correct method for decreasing exposure time (and increasing frame rate) is to window the CCD. See the next paragraphs.

The variables nr, nc, sr, and sc stand for "number of rows, "number of columns," "starting row," and "starting column" respectively. Values of nr, nc, sr, and sc for the current readout window are displayed below each variable. New values are typed into the box below, entered with a carriage return, and initiated by pushing the Set Camera button.

Note that though the CCD is 690 x 400 pixels, the largest possible window is 345 x 400 because it is a frame transfer system and the other half of the detector is devoted to reading out the image. Also note that on the guider display, the origin (0,0) is at the upper left corner of the image.

Binning 1 = no binning and is used for all guiding, though there may be instances when it is convenient to increase binning for acquisition. Guiding will not work with binning > 1. Binning may not be available on all guiders.

[root name] + observation number + [.extension]

and written to the designated directory. The root name, extension, and directory may be set in the 2nd Level. Default directory and name are /data/g[#].fits

The observation number will increment with each recorded image. The number may set by the user, but remember that if you set the number back, files with the same name will be overwritten without warning.

Recorded images will be named and saved according to the rule described in "Observation Number," above.

Directory, Root, and Suffix allow a directory to be specified where recorded images will be stored, and a naming scheme to be chosen. The values shown here (the default values) would save files to the /data directory in the form g[#].fits.

Recorded images are in FITS format.

Our thermoelectrically cooled cameras have been holding the CCD at about -40 to -50 degrees in cool weather. CCD temperatures will be somewhat higher in summertime.

Desired CCD temperature is set well below the attainable temperature (e.g., -100.0) to maintain the lowest possible temperature.