* local users only
MANUAL for the AUTO GUIDER of the AIP 70cm TELESCOPE
Follow the instructions in the telecope manual. If everything
is fine, turn your attention to the auto guider. (Don't forget
to switch on the second PC and monitor if not already done.)
If you see the pull-down menu, don't be afraid - essentially
you will need only two menu points.
[Camera -> Setup -> Setpoint]
Adjust the reference temperature of the CCD.
This has to be done in consecutive steps!!!
The heat sink is to small. When the difference between reference
temperature and actual temperature is to big, the heat sink can't
get rid of the produced heat, hence the cooling element takes more
power and produces more heat. An effective cooling of the CCD is no
Check the actual temperature (lower right corner on the screen).
If it doesn't fall and the power consumption of the cooling element
reaches 100 percent (the value in brackets), set the reference
temperature to a higher value (make the difference between actual
temperature and reference temperature smaller). Once the reference
temperature is reached, set a new reference temperature. The actual
temperature needed depends on the stars in the FOV of the guider.
If there is a bright source, some degrees below zero are sufficient.
Select guide star and exposure time
[Track -> Autoguide ]
Select the exposure time. The actual time depends of course on the
brightness of the guiding star. Start with 2 seconds, check the image
and - if it's necessary (that means not enough counts for the guiding
star) - choose a longer exposure time.
Once the exposure time is fixed,
select your guiding star with the white rectangular cursor on the
Press the "Enter" button twice and everything is fine.
After each exposure, the counts and the relative motion in pixel values
of the guiding star are shown. The pixel values should stay below
+/-1.0 (see below). In the case of clouds, the guider loses track and has
to be re-initialized.
[Track -> Autoguide -> Parameters] or
[Track -> Autoguide Parameters]
The auto guider moves the telescope via the mechanical telescope drive
mechanism. This mechanism has an immanent and an age-dependent tolerance,
makes it hard to calibrate the guider exactly. Another problem is the
non-linear motor activity of the drive for small motions as used by the
guider. This makes it sometimes necessary to adjust the guider parameters
manually - if the relative motion of the guiding star is growing after
each exposure (in x or y) or highly fluctuant. The parameters of interest
Relay--(+/-, x/y)--Speed and Minimum/Maximum move. (By the
way: x means RA and y means DEC). The aggressiveness mainly gives the reaction
time of the guider. High aggressiveness means a fast reaction even if there
is only a small difference in pixel values of the guiding star between two
successive exposures. Low aggressiveness means a lazy behaviour of the guider.
If the relative motion of the guiding star grows after each exposure, choose
a higher aggressiveness. If the relative motion is big but highly fluctuant
(+/-), decrease the aggressiveness. Minimum/maximum move gives the allowed
time for motor activity in milliseconds. The maximum move should always
be greater than 1000.
(Written by J. Vogel)