Lacerta M-GEN User Manual page 42

More on this value at 1.3.2. Changing the value takes effect imediately (at the next
exposure).
• exp.: (decimal, 50...4000 ms) profile
The same variable as the "expo.time" at Star Search screen. (They are identical.) The
used exposure (integraton) time for taking images for autoguiding.
• thresh.: (decimal, 1...99 %)
The threshold value to discriminate star and non-star pixels. The value means the
percentage to the saturation relative to the background pixel value (the minimum of
the noise suppressed background for each frame).
Generally a value of 10% is useful and is above the readout noise at any gain. If some
pixels randomly appear at the edge of the star ("
this value until the star's edge is no more 'noisy'.
If there is a fainter star close to our guiding star, this threshold can be also increased
until the faint star does not appear even for a moment. This is not advised if the
difference of their brightness is less than about 2 magnitudes.
AG start
or
•
To start or stop the autoguiding.
When starting, the latest star position will be the guiding center, where the star is to be
held. Later the guiding center can be overwritten with a new value (for example by the
RD function). The position is always a fractional (any "subpixel" position is allowed).
The autoguiding can't be started if there are no star (pixel) in the guiding window.
• <<: (button)
The display mode of the window at left is changed by this item (presing SET on it),
see display modes at 5.1.9.
pg ?/5: (button)
•
By selecting this item and pressing LEFT, RIGHT or SET the active page of the
Guiding screen can be changed. This item can be found on each page at the same
position.
Camera orientation (and calibration) page (2/5)
5.1.9.2
The Calibration's function is to determine the relationship between
the sky axes and the Camera coordinates and the actual correction
speeds for both sky axes. It is required to make the device know how the
mount will react on the autoguider signals and know how the guiding
star will move on the CCD. This screen contains the main elements of setting this 'camera
orientation' data.
The screen items are the following:
Invert RA, invert
•
AG stop: (button)
DEC: (switches)
gui mask
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" display mode), increase