16
U
U
t
t
i
i
l
l
i
i
t
t
y
y
F
F
e
e
a
a
t
t
u
u
r
r
e
e
s
s
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 rewinding 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.
3.
Use the UP and Down arrow keys to speed up or slow down the initial speed of the altitude motors when the arrow
buttons are pressed.
4. Press
the
STAR
key on the hand control again to activate the direction buttons again.
R
R
S
S
-
-
2
2
3
3
2
2
C
C
o
o
n
n
n
n
e
e
c
c
t
t
i
i
o
o
n
n
The NexStar HC has an RS-232 port on the back of the hand control, allowing it to be controlled using the
GuideStar
telescope control software. Linking the NexStar to a computer requires the use of a RS-232 cable (included in the HC
models of the NexStar, and an optional accessory for the GT models). The
GuideStar
software gives you all the "Go
To" features of the NexStar GT hand control including a 4,000 object database,
AutoAlign
based on date and location,
and helpful information for hundreds of objects.
To interface the NexStar with your computer, follow these steps:
1. Connect the phone jack end of the RS-232 cable to the port in the back of the hand control and the 9-pin
connector to the back of your computer.
2. Install
the
GuideStar
CD-ROM onto your computer and follow the on-screen instructions.
3.
Plug in power to the NexStar and start the
GuideStar
program.
4. From the Setup Screen you can test communication by clicking on the Test Port button after selecting a
Comm port (see Fig 4-3). If you receive a communication error message, select a different Comm port and
click Test Port until communication is successful.
5.
Once communication is established, update the following information on the Setup Screen:
