Object Library Menu File - Meade LX200 Instruction Manual

j. SLEW RATE: Option #10 in the TELESCOPE menu is for
changing the slew rate of the telescope. Slowing down the
slew rate results in less noise when the telescope moves; it
uses less power. To change the slew rate, follow these steps:
1. Press the M O D E key on the keypad
T E L E S C O P E / O B J E C T L I B R A RY menu appears. T h e
cursor should be next to the TELESCOPE option — if not,
press the PREV key to move the cursor up one space.
2. Press ENTER to select the TELESCOPE functions.
3. Press the PREV or NEXT keys to move the cursor to
option #10: SLEW RATE. The right side of the display,
shows the number 4. This represents the slew rate in
degrees per second.
4. Press the ENTER key to change the slew rate. Each
successive ENTER key press increments the slew rate by
1° per second.
5. After setting the desired rate, press the MODE key to
return to the TELESCOPE/OBJECT LIBRARY menu.
NOTE: The slew rate is not stored in permanent memory. Reset
it when the telescope powers up or accept the default rate of 4°
per second.
k. BACKLASH: The BACKLASH feature is available only in the
POLAR mode.
When taking long-exposure astrophotographs, guide the
photograph to make sure the telescope is tracking perfectly.
Otherwise stars will appear as ovals instead of pinpoints. Do
this by setting the LX200 keypad to the GUIDE speed,
monitoring the star location (e.g., with an off-axis guider), and
making small corrections to the telescope position by using
the N, S, E, and W keys.
When you make these corrections, you speed up or slow
down the R.A. motor (by pressing the E and W keys). The
Dec. motor, however, when activated (by pressing the N and
S keys) stops and reverses direction. Because of backlash in
the Dec. motor gearbox, the telescope delays a few seconds
when reversing direction.
The Dec. backlash feature compensates for the Dec. motor
gearbox backlash and provides instant telescope movement
when the motor is reversed.
To program the Dec. backlash, use this procedure:
1. Move to option #11 from the TELESCOPE menu. The
keypad display will show:
11) BACKLASH 00
The 00 in the display shows the number of arc-seconds of
backlash for which the LX200 is set to compensate (the
default setting is 0 arc-seconds).
2. While observing a star at high power, time the Dec.
movement delay when reversing the motor directions (by
pressing the N and S keys). Typical values are two to four
seconds.
3. The GUIDE speed for the Dec. motor is 15 arc-seconds per
second. Therefore, multiply the number of seconds of
delay by 15.
4. Press and hold the ENTER key for one second. The
keypad beeps and a blinking cursor appears on the keypad
display. Enter the number determined in step (c), above.
Press ENTER.
5. Check the time delay as described in step (b). If there is a
delay, increase the compensation number. If there is a
slight jump when reversing direction, the number is too
large.
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When reversing the direction in Dec., if the compensation
number is correct, the telescope moves almost instantly. This
compensation feature also works with popular CCD auto-
guiders, allowing for more accurate autoguiding. This number
is stored in permanent memory; you need not re-set it.
until the
l. FDR: The FIELD DE-ROTATOR (FDR) option is available only
in the ALTAZ mode. Selecting this option activates the field de-
rotator socket on the power panel. When it is active, the
display shows the number of arc-seconds of field rotation for
the part of the sky to which the telescope is pointing. When not
using the de-rotator, turn off this function.
Field rotation can range from almost no rotation (at certain
parts of the horizon) to infinity at the exact zenith (straight up).
The #1222 Field De-Rotator has a practical limit of 120 arc-
seconds per second. This creates a cone of just under 10°
where the de-rotator cannot keep up with the field rotation.
When taking exposures near the zenith, this number should be
monitored and the exposure stopped should the field rotation
approach 120 arc-seconds per second.
m. FAN: When the fan is plugged into the power panel, this switch
will turn the fan on and off. The fan will aid in the temperature
stabilization of the telescope. Extreme temperature variations
will require about 30 minutes of fan operation to stabilize.
During observations, the fan should be turned off to minimize
any vibrations.
n. DEC LEARN and DEC CORR (Declination correction) You
can correct for a star that drifts consistently North or South
during guiding. Move the arrow to DEC LEARN and press
E N T E R. Begin making drive corrections immediately by
pressing any of the direction (N, S, E, W) keys to keep the star
on the crosshair of the guiding eyepiece. Train in DEC LEARN
for at least half of your intended astrophoto exposure time.
The longer you train, the more accurate DEC LEARN will be.
Once you reach the desired time, press ENTER and the
training ceases.
The telescope counts how many times you pressed the N and
S keys. It chooses the direction based on the direction that
received more commands, and it averages the time between
key pushes in the chosen direction. Thus the telescope
corrects for Dec. drift (should your polar alignment be slightly
off) or increases the precision of your guiding on non-stellar
objects, such as comets and asteroids.
To play back your DEC LEARN training, move the arrow to
DEC CORRECTand press ENTER. To halt the playback press
ENTER again. To erase the DEC LEARN training, either move
the arrow back to DEC LEARN and press ENTER twice or turn
the telescope off. DEC LEARN and DEC CORR are available
only in POLAR mode.

2. OBJECT LIBRARY Menu File

The OBJECT LIBRARY menu file is the other half of the
TELESCOPE/OBJECT LIBRARY mode. With it you can be a
tourist of the sky or conduct research surveys of the 64,359
objects. The LX200 object library is accessible in the most
effective and user-friendly system ever designed for observers
and astrophotographers.
The core library, essentially a "greatest hits of the sky, "
encompasses the planets of our solar system from Mercury to
Pluto, 351 stars (doubles, variables, Pole Stars), the entire
Messier catalog of 110 objects, 7840 of the finest galaxies, diffuse
and planetary nebulae, and globular and open-star clusters.
The position epoch of these objects is for real time, updated each
time you turn on your LX
their orbits calculated. This qualifies the LX200 as the most
accurate integrated object library available; it never requires
updated software for precession of the stars or planetary orbital
changes.
200
. Even the planet's positions have