Sky Intensity average
- the calculated luminosity of the background sky surrounding
the guide star. This value is subtracted from every pixel intensity value within the guide
star region mask area before using the pixels values to calculate the centroid.
Star intensity threshold
- this value is the threshold intensity level that the program
uses to decide whether a given pixel is part of the sky background or part of the pixels
belonging to the guide star. This threshold is set to a point somewhere between the sky
intensity level and the max pixel intensity detected in the pixels under the guide star.
Changing the setting of the
‘
Pixel intensity threshold
’
slider will allow you to change this
threshold. Too close to the bottom and you will get poor calculation results in images
that have high noise in the background sky pixels. Too high, and the calculation will
lose precision.
Max Pixel Intensity
- this value is the pixel intensity level of the brightest pixels under
the guide star.
Num significant Pixels
- the total number of pixels that are above the
‘
Star intensity
threshold
’
level. This number should be at least a dozen or so pixels for a good guide
star position calculation. If too low, then a lower setting on the
‘
Pixel intensity threshold
’
slider or a longer integration time should be set.
Pixel intensity threshold slider -
this control allows you to set the
‘
Star intensity
threshold
’
parameter.
# readings to average
- this parameter allows you to define how many readings are
averaged to obtain the guide star position calculation. Normally, this is set to
‘
1
’
and the
position calculation is based only upon the last image taken by the guide camera. In
certain situations, such as during poor seeing conditions, you might want to average two
or more readings before using the guide star position calculation.
Guide star average
- the result of averaging
‘
# readings to average
’
in guide star posi-
tion. These values should be the same as
‘
Guide Star (raw)
’
when only one image is
being averaged.
fishcamp engineering
Starfish
Guide Camera