Specifications

SBIG STF-8300 Manual

6. Glossary

Antiblooming- When a CCD pixel has reached its full well capacity,

electrons can effectively spill over into an adjoining pixel. This is

referred to as blooming. Kodak CCDs like the KAF-0402LE with

the antiblooming option can be used to help stop or at least reduce

blooming when the brighter parts of the image saturate.

Astrometry - Astrometry is the study of stellar positions with respect to a

given coordinate system.

Autoguider - All SBIG CCD cameras have auto guiding or "Star Tracker"

functions. This is accomplished by using the telescope drive

motors to force a guide star to stay precisely centered on a single

pixel of the CCD array. The camera has four relays to control the

drive corrector system of the telescope. The CCD camera head is

installed at the guide scope or off axis guider in place of a guiding

eyepiece.

CCD - The CCD (Charged Coupled Device) is a flat, two dimensional array

of very small light detectors referred to as pixels. Each pixel acts

like a bucket for electrons. The electrons are created by photons

(light) absorbed in the pixel. During an exposure, each pixel fills

up with electrons in proportion to the amount of light entering the

pixel. After the exposure is complete, the electron charge buildup

in each pixel is measured. When a pixel is displayed at the

computer screen, its displayed brightness is proportional to the

number of electrons that had accumulated in the pixel during the

exposure.

Correlated Double Sampling - Correlated Double Sampling (CDS) is

employed to lower the digitization errors due to residual charge in

the readout capacitors. This results in lower readout noise.

Dark Current - Dark Noise or Dark Current is the result of thermally

generated electrons building up in the CCD pixels during an

exposure. The number of electrons due to Dark Noise is related to

just two parameters; integration time and temperature of the CCD.

The longer the integration time, the greater the dark current

buildup. Conversely, the lower the operating temperature, the

lower the dark current. This is why the CCD is cooled for long

integration times. Dark noise is a mostly repeatable noise source,

therefore it can be subtracted from the image by taking a "Dark

Frame" exposure and subtracting it from the light image. This can

usually be done with very little loss of dynamic range.

Dark Frame - The user will need to routinely create image files called

Dark Frames. A Dark Frame is an image taken completely in the