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The NexStar electronic hand control comes with a
Star
function key that allows you to change certain parameters
of the hand controls functions, such as the tracking mode, the directional logic of the arrow keys and backlash
compensation of the motor gears and azimuth tracking.
Tracking Mode:
The NexStar electronic hand control allows your telescope to track objects in the following
modes: EQ North, EQ South, Alt-Az and Terrestrial (off). By default the tracking motors are turned off, allowing
you to slew the telescope and observe land objects. If using your NexStar on an optional equatorial wedge, it will
be necessary to turn the tracking motor on. To turn on the tracking motors:
•
Press the
STAR
key on the hand control. The
star
light (1) on the hand control will light up to indicate
that the button has been pressed and the first (left most) indicator light will be
lit showing that you are in the tracking menu with tracking set to off. (see
figure).
•
Press the
RATE
button once to select equatorial tracking in the Northern
Hemisphere.
•
Press the
RATE
button twice to select equatorial tracking in the Southern
Hemisphere.
•
Press the
RATE
button three times to select Alt-Az tracking.
Once set continue pressing the STAR button until the star light goes off.
Alt-Az Tracking
– The NexStar gives you the ability to adjust the tracking speed in both altitude (up and down)
and azimuth (side to side) to allow you to track an object as it moves across the sky. Once a celestial object is
centered in the field of view of the eyepiece, notice which direction the object appears to drift in the eyepiece.
Using the arrow buttons, determine which buttons you need to press in order to move the object back to center.
Which ever buttons that you use to center the object will be the same buttons you will need to adjust when
setting the Alt-Az motor speed. The direction and speed at which an object drifts out of the field of view of the
eyepiece depends on what part of the sky the object is located. This mean that Alt-Az tracking will need to be
adjusted each time you move the telescope significantly to a different part of the sky. For guidelines and tips on
correctly adjusting your Alt-Az tracking speed, see the table at the end of this section. To set the Alt-Az tracking
rate, do the following:
1. Once the desired object is centered in the eyepiece and you have determined which arrow buttons need
to be pressed to keep the object centered, press the
STAR
key on the hand control.
2. Press
the
RATE
button three times to select Alt-Az tracking.
3. Select the arrow button that you were using to center the object and press it once. This will increase
the motor speed in that direction. If the star continues to drift in the same direction as before, press the
same direction button until the star no longer drifts in that direction. If the star begins to drift in the
opposite direction, then press the opposite arrow button to reverse the motion. Use the table at the end
of this section to help determine the initial tracking rates.
4. Using the remaining two arrow buttons, repeat the same process for the telescope’s other axis if
necessary.
Note: You can adjust both axes at the same time if you wish. A reticle or crosshair eyepiece can be helpful in
detecting subtle drift and determining direction of movement.
Anti-backlash
– All mechanical gears have a certain amount of backlash or "play" between the gears. This
play is evident by how long it takes for a star to move in the eyepiece when the hand control direction buttons are
pressed (especially when changing directions). The NexStar's anti-backlash feature allows the user to
compensate for backlash by having the hand control quickly rewinding the motors enough to help reduce the
play between the gears. The amount of compensation needed depends on the slewing rate selected; the slower
the slewing rate the longer it will take for the star to appear to move in the eyepiece. The NexStar hand control
allows you to change the backlash setting for each axis, one at a time. To change the backlash compensation:
1. Press
the
STAR
key on the hand control. The activation light (1) on the
hand control will light up to indicate that you have activated the menu
functions.
Backlash Compensation Menu
Off
EQ-North
EQ-South
Alt-Az
