Lacerta M-Gen User Manual page 45

5.1.10.2.1 Calibration screen
The screen displays all of the current calibration data if there is
one. If there is no calibration data present, "no data" text is shown (see screenshot at right)
and two options are possible: starting a new calibration with the
restoring the previous one with the
The calibration procedure is the following:
First the DEC axis is moved according to the settings given in "guider settings" screen
(AG speed DEC value). (This helps the calibration to move the desired amount without a
knowledge.) If the star moved a little (no backlash is on the DEC now) the measurement of
the DEC direction and correction speed is started. After it the RA axis' direction and speed
can be measured now easier, the device supposes that the actual RA speed is equal or less
than the DEC's. (Less due to the actual DEC coordinate where the mount points to.)
After all is finished, both the directions and speeds are stored as the calibration data. The
correction speeds precision can't be checked diretly but the directions can. In an ideal case
these directions (vectors) are orthogonal to eachother but during the measurement the star
may drift some due to polar misalignment or due to the periodic error of the RA axis. (The
constant speed drifts are mostly corrected by the measurement method.)
After the calibration the orthogonlity measure is displayed on the screen as "ortho.", in
percent. The interpretation of the resulting value is described later.
The calibration procedure can be interrupted any time by pressing ESC. The mount is
moved back to the start position, which can be interrupted as well. This is done too, after all
the calibration steps has run. (Assuming there is no backlash, it's precise.)
If a calibration has run with no error, a calibration data is
present. The data consists of the directions (on the CCD's surface)
of the two axes (RA and DEC) and their actual correction speeds.
This is displayed on the screen as on the screeenshot at right:
 The two directions are shown in the "guiding window" that is now used for
displaying only these vectors. Both are normalized to equal length displayed.
 RA and DEC's correction speeds are shown at top right, in pixels per second unit
(px/s).
 The next row shows the orthogonality measure of the two axes' vectors. This is
calculated as follows:
RA
Recall last
RA and DEC vectors are normalized (to unit
DEC
length). Ther error (e) is the scalar multiply
α
of these vectors:
e = (RA · DEC) = cos(α)
e
The precision of the measurement, the
"orthogonality" (o) is:
o = (1 – e) * 100 %
item.
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Calibrate
button and