Celestron NexStar HC Telescope User Manual


 
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4.
Star Key:
Gives the user access to the utility functions of the hand control, such as changing the direction of the arrow
keys and backlash compensation.
5.
Hand Control Slew Rate Indicator Lights:
Displays the speed at which the telescope will move when each direction
button is pressed.
Rate Button
Pressing the RATE key (3) allows you to instantly change the speed rate of the motors from high speed slew rate to precise
centering rate or two speeds in between. Each rate corresponds to one of the indicator LED lights (5) on the hand control. From
left to right, the corresponding speeds are as follows:
Rate
1 For fine centering of objects in the eyepiece
2 For scanning around for objects in the eyepiece
3 For centering bright stars in the Star Pointer
4 For slewing around the sky from object to object
The hand control has a "double button" feature that allows you to instantly speed up the motors without having to choose a speed
rate. To use this feature, simply press the arrow button that corresponds to the direction that you want to move the telescope.
While holding that button down, press the opposite directional button. This will increase the slew rate to approximately 1.5º per
second (equal to the third rate on the hand control). This feature will only function if the telescope is currently set at a speed rate
of 1 or 2.
Utility Features
The NexStar HC hand control comes with a Star
function key that allows you to change certain parameters of the hand controls
functions, such as the directional logic of the arrow keys, backlash compensation of the motor gears and azimuth tracking.
Direction Buttons:
When looking at a star through an eyepiece or star diagonal, the direction that the star moves when the Up
and Down arrow buttons are pressed will be reversed from when the same object is being centered in the
Star Pointer Finderscope. For example, when a star is being centered in the telescope's eyepiece, it may
appear to move upward when the down arrow button is pressed (and visa-versa) even though the telescope
tube is actually moving downward. This is why it is convenient to be able to change the arrow button
direction when switching from using the Star Pointer to the eyepiece. To reverse the direction of the Up and
Down arrow buttons:
1. Press the
STAR
key on the hand control. The activation light (1) on the hand control will light up to indicate that the
button has been pressed. When the button has been pressed, the four direction buttons (2) will be non-operational until
the button is pressed again.
2. Press the
RATE
button on the hand control.
3. Press the
STAR
key on the hand control to activate the direction buttons.
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 arrow 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 rewind the motors just enough to eliminate the play between 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. To change the backlash compensation:
1. Press the
STAR
key on the hand control.
2. Use the Right and Left arrow keys to speed up or slow down the initial speed of the azimuth motors when the arrow
buttons are pressed. For example, if it takes a star too long to move in the eyepiece when the hand control arrow buttons
are pressed, then press the Right arrow button to speed up the initial motor speed. The buttons can be pressed repeatedly
to increase the initial motor speed even more.