Celestron NexStar 80GTL - Manual (Page 19)

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objects are relative to the location of the telescope, they are only valid for that exact location. To save land objects,
once again center the desired object in the eyepiece. Scroll down to the "
Save Land Obj" command and press
ENTER. The display will ask you to enter a number between 1-25 to identify the object. Press ENTER again to save
this object to the database.
Enter R.A. - Dec: You can also store a specific set of coordinates for an object just by entering the R.A. and
declination for that object. Scroll to the "
Enter RA-DEC " command and press ENTER. The display will then ask
you to enter first the R.A. and then the declination of the desired object.
GoTo Object: To go to any of the user defined objects stored in the database, scroll down to either GoTo Sky Obj
or Goto Land Obj and enter the number of the object you wish to select and press ENTER. NexStar will
automatically retrieve and display the coordinates before slewing to the object.
To replace the contents of any of the user defined objects, simply save a new object using one of the existing identification
numbers; NexStar will replace the previous user defined object with the current one.
Get RA/DEC - Displays the right ascension and declination for the current position of the telescope.
Get Alt-Az - Displays the relative altitude and azimuth for the current position of the telescope.
Goto R.A/ Dec - Allows you to input a specific R.A. and declination and slew to it.
Goto Alt-Az - Allows you to enter a specific altitude and azimuth position and slew to it.
To store a set of coordinates (R.A./Dec) permanently into the NexStar database,
save it as a User Defined Object as described above.
Utility Features
Scrolling through the MENU options will also provide access to several advanced
utility functions such as anti-backlash compensation and slew limits.
Setup Time-Site - Allows the user to customize the NexStar display by changing
time and location parameters (such as time zone and daylight savings).
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 features allows the user to compensate for
backlash by inputting a value which quickly rewinds 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. Therefore, the anti-backlash compensation will have
to be set higher. You will need to experiment with different values; a value between
20 and 50 is usually best for most visual observing, whereas a higher value may be
necessary for photographic guiding.
To set the anti-backlash value, scroll down to the anti-backlash option and press
ENTER. Enter a value from 0-100 for both azimuth and altitude directions and press
ENTER after each one to save these values. NexStar will remember these values and
use them each time it is turned on until they are changed.
Helpful
Hint
SETUP TIME-SITE
AZM POSITIVE
AZM NEGATIVE
ALT POSITIVE
ALT NEGATIVE
ANTI-BACKLASH
SLEW ALT MAX
SLEW ALT MIN
SLEW LIMITS
AZM BUTTONS
ALT BUTTONS
DIRECTION BUTTONS
DISPLAY OFF
DISPLAY ON
KEY PAD OFF
KEY PAD ON
LIGHT CONTROL
SELECT MODEL
UTILITIES
MENU