Santa Barbara Instrument Group ST-i Operating Manual page 28

dark. The shutter covers the CCD. Dark Frames are subtracted
from normal exposures (light frames) to eliminate fixed pattern
and dark current noise from the image. Dark Frames must be of the
same integration time and temperature as the light frame being
processed.
FITS Image File Format - The FITS image file format (which stands for
Flexible Image Transport System) is a common format supported
by professional astronomical image processing programs such as
IRAF and PC Vista.
Flat Field - A Flat Field is a image with a uniform distribution of light
entering the telescope. An image taken this way is called a flat
field image and is used with CCDOPS to correct images for
vignetting.
Focal Reducer - A Focal Reducer reduces the effective focal length of an
optical system. It consists of a lens mounted in a cell and is usually
placed in front of an eyepiece or camera. With the relatively small
size of CCDs compared to film, focal reducers are often used in
CCD imaging.
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 locations of the image
file.
Light Frame - The Light Frame is the image of an object before a Dark
Frame has been subtracted.
Photometry - Photometry is the study of stellar magnitudes at a given
wavelength or bandpass.
Pixel Size - The smallest resolution element of a CCD camera is the CCD
pixel.
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.
SBIG ST-i Manual
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