29
■ Mount Lower Limit: Allows you enter a percentage that sets a lower limit as to
how far the optical tube can swing downward during a programmed slew. (Note
that it does not prevent you from performing a manual slew past this limit.) This
is useful when you have a large optical tube (12" model) or have a dewshield
attached to the telescope—you can prevent it from striking the telescope base.
-90% (straight down) is the maximum value that can be entered.
■ Train Drive: All telescopes have a certain amount of "backlash" (looseness in the
interplay of gears). This menu allows you to compensate for the backlash in the
the Altitude and Azimuth motors—which helps locate objects with more precision.
If you are experiencing any problems with pointing accuracy, follow the procedure
described in
APPENDIX D: TRAINING THE DRIVE, page 59, to insure accurate
pointing and tracking. Also see CALIBRATE SENSORS, below.
■ Calibrate Sensors: This menu allows you to improve your telescope's pointing
accuracy to alignment stars. It calibrates to correct slight mechanical misalign-
ment due to transport, vibration, or aging. It is recommended that calibration be
performed once on a new telescope after the user initially assembles it.
When this menu is selected, the telescope slews to Polaris. Autostar II then
prompts you to center Polaris and to press ENTER. Autostar II uses the position
of Polaris to fine tune the position of North and also detects level for the base of
the telescope.
■ Tracking Rate: Changes the speed at which the telescope tracks targets in the
sky.
a. Sidereal: The default setting for Autostar II; sidereal rate is the standard rate
at which stars move from East to West across the sky due to the rotation of
the Earth.
b. Lunar: Choose this option to properly track the Moon over long observing
sessions.
c. Custom: Allows entry of user-defined tracking rates.
■ Guiding Rate: Allows you to change the base slew speed, 1x. Enter a percent-
age of the speed (either more or less than 100%) and press ENTER. This func-
tion may be useful in guiding the telescope during CCD and long-exposure pho-
tography. See SLEW SPEEDS, page 17, for more information.
■ Reverse L/R: Reverses the functions of the Left and Right Arrow keys for con-
trolling the telescope's motion (i.e., the Right key moves the telescope to the left).
■ Reverse U/D: Reverses the functions of the Up and Down Arrow keys for con-
trolling the telescope's motion (i.e., the Up key moves the telescope down).
■ Home Sensors: Turns off or on the True North and True Level sensors, if pre-
ferred, for Easy, One-Star, and Two-Star alignment. User must then manually
level the telescope and point the telescope to True North during alignment.
Default setting is "On."
■ Dec. PEC: Allows you to perform periodic error correction on the Dec. drive worm
gear. Must be performed with a high-power reticle (eg., 9mm).
■ R.A. PEC: Allows you to perform periodic error correction on the R.A. drive worm
gear. Must be performed with a high-power reticle (eg., 9mm).
■ High Precision: If High Precision is turned on, when looking for a faint celestial
object (e.g., a nebula or galaxy), Autostar II first slews to a nearby bright star and
displays "ENTER to Sync." Center the star in the eyepiece, then press ENTER.
At that point the telescope has a high precision alignment to that part of the sky
and it then slews to the object that was originally requested.
Targets: Switches between Astronomical targets and Terrestrial targets. If
"Astronomical" is selected, the telescope tracking motor is activated and any object
you observe will remain centered in the eyepiece. If "Terrestrial" is selected, the track-
ing motor is turned off. See TO TRACK AN OBJECT AUTOMATICALLY, page 18.
Site provides access to several options including:
■ Select: Displays the currently selected observing site. Use the Scroll keys to
cycle through all available sites (see
ADD below). Press ENTER when the site
Tip:
If the "ENTER to Sync"
feature is accessed by mis-
take (holding the ENTER
key for more than 2 sec-
onds), press MODE to
return to the previous
screen.
Do you want to learn how to
perform the periodic error
correction procedure?
See
PERIODIC ERROR COR-
RECTION
, page 39.
