Specifications

Section 4 - Glossary
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Frame Transfer CCDs - Frame Transfer CCDs are CCDs that have a metal mask over some
portion (usually half) of the pixel array. The unmasked portion is used to collect the
image. After the exposure is complete, the CCD can very quickly shift the image from
the unmasked portion of the CCD to the masked portion, thus protecting the image
from light which may still be impinging on the CCD. This acts as an electronic shutter.
Full Well Capacity - Full Well Capacity refers to the maximum number of electrons a CCD
pixel can hold. This number is usually directly proportional to the area of the pixel.
Histogram - The Histogram is a table of the number of pixels having a given intensity for each
of the possible pixel intensities. Remember that, in the end, the image file is nothing
more than a list of pixel values, one for each CCD pixel.
Light Frame - The Light Frame is the image of an object before a Dark Frame has been
subtracted.
Path/Filter - The Path setting tells CCDOPS which directory and disk drive to find and store the
image files. In essence, it defines the current directory. The filter controls which image
files are shown in the Open directory. Only files that match the filter are shown. For
example, a filter setting of "*.255" will only show files that have a "255" extension.
Photometry - Photometry is the study of stellar magnitudes at a given wavelength or bandpass.
Photons/ADU - This is an indication of the camera's gain in converting incoming light into
image counts. This value is used with programs such as Hidden Image. For any image
you take the Photons/ADU is shown in the Parameters command from the Image menu.
Pixel Size - The smallest resolution element of a CCD camera is the CCD pixel. The pixel size
for your camera is 10 microns square (10 by 10 microns)
Planet Mode - Planet Mode is the most useful way to achieve focus. When you select Planet
mode, a full frame is exposed, downloaded, and displayed on the computer monitor. A
small window can be placed anywhere in the image area and the size of the window can
be changed. Subsequent downloads will be of the area inside the box resulting in a much
faster update rate.
Quantum Efficiency - Quantum Efficiency refers to the fractional number of electrons formed
in the CCD pixel for a given number of photons. Quantum Efficiency is usually plotted
as a function of wavelength.
Readout Noise - Readout noise is associated with errors generated by the actual interrogation
and readout of each of the CCD pixels at the end of an exposure. This is the result of
fixed pattern noise in the CCD, residual charge in the readout capacitors and to a small
extent, the noise from the A/D converter and preamplifier.
Readout Streaking - When a bright object is imaged using a short exposure time, readout
streaking can occur. Readout streaking can look similar to blooming except it extends
across the entire image passing through the bright object. This is a result of image shift
at the beginning and again at the end of an exposure due to frame transfer. The readout
streaking is usually very faint with respect to the overall image and can sometimes be
eliminated from the display image by slightly raising the background level.
Resolution Mode - The resolution of a CCD camera is determined by pixel size. Pixel size can
be increased by combining or binning more than one pixel and displaying it as one pixel.
Doing so decreases the effective resolution but speeds up the download time of the
image. Maximum resolution is determined by the smallest size of the individual CCD
pixel.
Response Factor - Response Factor is a multiplier used by CCDOPS to calibrate a telescope for
photometric calculations. The Response Factor multiplied by 1000 is the number of