
10
4.5 Mount calibration
The telescope must not be touched during calibration, otherwise the relevant
parameters could not be calculated correctly. This also applies to the Control
Paddle unit which must not stay in your hand!
Once calibration is over, the parameters are permanently stored into the
SmartGuider’s internal memory (EEPROM) for later use, provided that the
following precautions are taken into account:
1. Always guide on stars lying in the same side of the sky (with respect to the
local meridian) as that where the calibration was last performed;
2. NEVER take the camera off the guide scope;
3. NEVER rotate the camera in the guide scope focuser.
In all other cases, the camera must always be recalibrated.
It might take a relatively long time for the calibration process to complete,
especially with guide scopes of short focal length (under 500 mm).
It is also advisable not to use too dim a star for calibration, otherwise just a few
thin clouds or a little dew on the lenses could cause the star to be lost and
jeopardize the final result of this important process.
4.6 Autoguiding and aggressiveness
In practice, the aggressiveness parameter defines the “reaction threshold” (in
terms of sensor pixels), i.e. the value of the offset between two consecutive
exposure cycles above which the camera will make a correction.
The lower the aggressiveness, the higher the tracking error allowed and vice-
versa.
HIGH values are suitable when using small refractors featuring a focal length
1,5-2 times smaller than the main instrument. MILD values are for guide scopes
of about the same focal length and LOW ones are best in case of very long guide
scopes or off axis guiding (typically SCTs).
During autoguiding, the trend of the X and Y graphs should always be staying
as smooth as possible. It is advisable to start off with default values for