Library Object Keys; Star Alignment; 1-Star With Known Site; Unknown Site - Meade LX200 Instruction Manual

2. Telescope Position. The first display shows the RA and
DEC (telescope position in stellar coordinates) and the
second display (accessed by pressing the ENTER key)
shows the telescope position in ALTAZ coordinates.
3. Time and Date. The first display shows local and Sidereal
time and the second display (accessed by pressing the
ENTER key) shows the date.
4. Timer and Freq. This display is a countdown timer and
allows the user to change drive rates. These are
advanced features.
All Off. This mode simply turns off all displays and
5.
backlighting. You can also adjust the backlighting
brightness by pressing the ENTER key and using the
PREV and NEXT keys to adjust the brightness.
f.

Library Object Keys

While in any of the 5 main keypad display modes, you can
directly access the library objects by using the M, STAR, or
CNGC keys (see APPENDIX C, page 31, of this manual for more
information on the 64,359 Object Library). Simply press an
object key, and type in the number of the object desired,
followed by ENTER. For example, a good first object for the
first part of the year is M42 — the Great Orion Nebula.
Press the M key, the 4 key, the 2 key, and finally the ENTER
key. The display will show data on the object (name, rating,
object type, brightness, size). Now press GO TO. The
telescope will automatically slew to M42.
If the object entered is not above the horizon, the keypad hand
controller will display the message "Object Below Horizon."
Other good first objects (if above the horizon) are any of the M
objects — from M1 to M 110, and the planets. To find a planet
enter: (NOTE: 903 is the Moon.)
OBJECT LIBRARY PLANET LEGEND
PLANET STAR #
MERCURY
901
VENUS
902
MARS
904
JUPITER 905

4. Star Alignment

The 2-Star initialization routines provide three options for
aligning the LX200 telescope when in the ALTAZ mode.
NOTE: The 2-Star initialization routines only apply to the ALTAZ
alignment mode (see MODE FUNCTIONS, page 16, for POLAR
and LAND mode initialization).
The first and second options require that entry of the SITE and
TIME information as described in Entering Basic Information
(page 10). The third option is used when the SITE information
is not known or has not been entered into the LX200's memory.
a. 1-Star with Known SITE
The 1-Star alignment routine was explained in detail in Setting
Up the Telescope (page 11).
b. 2-Star at Known SITE
To use the 2-Star alignment procedure at a known site, follow
these steps:
1. Select the 2-Star alignment (by pressing the "2" key); the
keypad display will prompt you to level the base. This
leveling step requires a rough level only and, unlike the 1-
Star alignment routine, does not affect the pointing
accuracy of the telescope. (See Section d. below for a
summary of the differences in telescope operation when
selecting each of the three alignment procedures.)
2. After leveling the base and pressing ENTER, follow the
keypad display prompts to select the first alignment star.
Slew to that star using the N, S, E, and W keys.
- 13 -
PLANET STAR#
SATURN
906
URANUS
907
NEPTUNE
908
PLUTO 909
3. Follow the keypad display prompts to choose and center
the the second alignment star. Be sure to use the keypad
to slew to the second star. After pressing the ENTER key
in the last step, the keypad display should show the
TELESCOPE/OBJECT LIBRARY screen.
Important Note: Whenever using either of the 2-Star
alignment procedures (at a known SITE or at an unknown
SITE), choosing the proper two stars will determine the
pointing accuracy of the telescope. Choose two stars that are
not too close together — try to use stars that are at least 90°
apart. Do not use Polaris because RA changes very fast at the
Pole and minor centering errors translate to large RA pointing
errors. Also, avoid stars near the zenith (straight up) since
azimuth changes very fast in this area. Generally speaking,
choosing two stars as far apart as possible will yield very
accurate pointing, often within a few arc minutes.
The LX200 calculates the distance between the two stars that
you chose in the alignment steps and compares this to the
distance that you actually slewed the telescope. This is a check
to be sure you centered the correct stars during the alignment
steps. Should the LX200 discover a discrepancy, the keypad
will display an "Align Mismatch — Check Stars" message. If
you get this message after aligning the telescope, check that
you are using the correct stars and align again.
c. Unknown SITE
To use the LX200 telescope at an unknown location, use the
following procedure:
1. Select site #5 (UNKNOWN) from the SITE menu.
NOTE: This site cannot be edited like site numbers 1 to 4 as
described in Entering Basic Information, page 10.
2. Follow the keypad display prompts to select and center
the two alignment stars.
As described above, the LX200 will check the accuracy of the
two stars and give the "Align Mismatch — Check Stars"
message if it detects an error.
d. Which Alignment Method to Use?
Each of the three method described above has advantages and
disadvantages. The following table summarizes these
properties.
1-Star
Known
Pointing Level
Accuracy
of
Determined Telescope
By:
Atmospheric Yes
Refraction
Correction*
Atmospheric
Level
Refraction of
Correction
Telescope
Determined
By:
When Best used
Best
when the
Used telescope is
permanently
mounted
and
accurately
leveled
* Atmospheric Refraction Correction: Light from an astronomical
object is "bent," (refracted) as it passes through the atmosphere.
This bending is more pronounced near the horizon because there is
more atmosphere for the light to pass through, and it shifts the
apparent position of the star. The LX200 calculates this bending and
compensates for it when slewing to objects near the horizon.
2-Star 2-Star
Known Unknown
2-Star 2-Star
Alignment Alignment
Yes No
Level Not
of Applicable
Telescope
Best used Best used
on a when the
transportable SITE
telescope information
with the is not
SITE available
information
available