29
(Note that it does not prevent you from performing a manual slew past this limit.)
This is useful when you have a camera or other peripheral attached to the tele-
scope—you can prevent it from striking the telescope base. 90 (straight up) is the
maximum value that can be entered.
■
Mount Lower Limit: Allows you enter a number from 0 to 90 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 tele-
scope base. -90 (straight down) is the maximum value that can be entered.
■
Park Position: For permanently mounted telescopes only. After aligning your tel-
escope, select this menu and power down the telescope. The alignment set-
tings—level, North, time, alignment stars—are stored in Autostar II's memory and
are remembered after you power off the telescope. When you power on the tel-
escope, "Automatic Alignment" displays after the start up routine. Press MODE
(do not press ENTER). The telescope remembers its alignment and you can con-
tinue viewing or performing other operations without aligning the telescope again.
Park Position provides two options. Use Current Position uses the last position
set by the user. Use Default Position levels telescope and points it North.
■
Calibrate Home: For permanently mounted telescopes only. After aligning your
telescope, select this menu and the alignment settings—level, North, time, align-
ment stars—are stored in Autostar II's memory and are remembered after you
power off the telescope. You can enable Autostar II to retrieve and automatical-
ly align your telescope using these settings the next time you power up by choos-
ing the Align on Home menu. See
ALIGN ON HOME
, page 28, for more informa-
tion. Note: This method is not as precise as
PARK POSITION
(see above).
■
Anti-Backlash: This option allows you to change the backlash along either the
R.A. and the Dec. axes by entering a number from 0% to 199%. This sets the
backlash in the way the Arrow keys move the telescope along an axis. If you enter
a value near 199%, telescope responds more quickly as you hold down an Arrow
key. If you enter a value near 0%, it takes longer for the tube to respond as you
hold down an Arrow key. Experiment with this option: Try changing the values until
the motion of the telscope (while holding down an Arrow key) feels comfortable to
you.
■
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.
■
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 (less than 100%) and press ENTER. This function may be use-
ful in guiding the telescope during CCD and long-exposure photography. See
SLEW SPEEDS
, page 17, for more information.
Note:
Custom Tracking Rate
allows you to enter values
from -999 (stands for -
99.9%) to 999 (stand for
+99.9%). The lower the
number, the slower the rate;
the higher the number the
faster the rate. If you enter
-999, the telescope will
move so slow as to appear
to be stopped. If you enter
999, the telescope will be
moving at approximately
twice the tracking rate.
