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Fig.12: Keypad Hand Controller.
KEYPAD HAND CONTROLLER
The LX10's standard-equipment keypad hand controller (Fig.
11) plugs into the telescope's control panel and is designed for
micro-guiding the telescope during long exposure astro-
photography, yielding precise corrections in R.A. at 2x speed.
For single-axis 2x corrections in R.A., press and hold either the
"W" or "E" key as necessary. Release to resume normal
sidereal tracking speed of the telescope's main drive system.
Note: The word "sidereal" refers to the rate at which stars
appear to move as the Earth rotates on its axis. Thus, "sidereal-
rate tracking"refers to the speed at which the telescope's motor
drive moves the telescope, in order that stars appear stationary
when viewed through the telescope.
To facilitate long-exposure astrophotography where minor
corrections of the telescope's position are required in both R.A.
and Dec, the optional Meade LX10 Electric Declination Motor
(Fig. 14) permits dual-axis control by activating the "N" (north)
and "S" (south) keys of the keypad (see O P T I O N A L
ACCESSORIES, page 15).
With the optional Declination motor attached, making minor
corrections in Declination during long-exposure astrophoto-
graphy is accomplished by pressing and holding either the "N"
or "S" keys of the keypad. When you have completed the
correction, release the selected key.
ASTRONOMICAL OBSERVING
The LX10's wide range of high-performance standard features
make this telescope an excellent observing tool for the serious
amateur astronomer. The range of observable astronomical
objects is, with minor qualification, limited only by the
observer's motivation.
This section provides a basic introduction to the terminology
associated with astronomy, and includes instructions for
finding, following and photographing celestial objects.
1. Celestial Coordinates
Celestial objects are mapped according to a coordinate system
on the Celestial Sphere, the imaginary sphere on which all
stars appear to be placed. This celestial object mapping system
is analogous to the Earth-based coordinate system of latitude
and longitude.
The poles of the celestial coordinate system are defined as
those two points where the Earth's rotational axis, if extended
to infinity, north and south, intersect the celestial sphere. Thus,
- 11 -
the North Celestial Pole is that point in the sky where an
extension of the Earth's axis through the North Pole intersects
the celestial sphere. This point in the sky is located near the
North Star, Polaris.
In mapping the surface of the Earth, lines of longitude are
drawn between the North and South Poles. Similarly, lines of
latitude are drawn in an east-west direction, parallel to the
Earth's Equator. The Celestial Equator is a projection of the
Earth's Equator onto the celestial sphere.
Fig.13: The Celestial Sphere.
Just as on the surface of the Earth, in mapping the celestial
sphere, imaginary lines have been drawn to form a coordinate
grid. Thus, celestial object positions on the Earth's surface are
specified by their latitude and longitude. For example, you
could locate Los Angeles, California, by its latitude (+34°) and
longitude (118°); similarly, you could locate the constellation
Ursa Major (which includes the Big Dipper) by its general
position on the celestial sphere:
R.A.: 11hr; Dec: +50°.
1.
Declination: The celestial analog to Earth latitude is called
Declination, or "Dec", and is measured in degrees,
minutes and seconds (e.g., 15° 27' 33"). Declination
shown as north of the celestial equator is indicated with a
"+" sign in front of the measurement (e.g., the Declination
of the North Celestial Pole is +90°), with Declination south
of the celestial equator indicated with a "–" sign (e.g., the
Declination of the South Celestial Pole is –90°). Any point
on the celestial equator itself (which, for example, passes
through the constellations Orion, Virgo and Aquarius) is
specified as having a Declination of zero, shown as 0° 0'
0".
2.
Right Ascension: The celestial analog to Earth longitude
is called "Right Ascension," or "R.A.," and is measured in
time on the 24 hour "clock" and shown in hours ("hr"),
minutes ("min") and seconds ("sec") from an arbitrarily
defined "zero" line of Right Ascension passing through the
constellation Pegasus. Right Ascension coordinates range
from 0hr 0min 0sec to 23hr 59min 59sec. Thus there are
24 primary lines of R.A., located at 15 degree intervals
along the celestial equator. Objects located further and
further east of the prime Right Ascension grid line (0hr
0min 0sec) carry increasing R.A. coordinates.
All celestial objects are specified in position by their celestial
coordinates of Right Ascension and Declination. T h e
telescope's R.A. and Dec setting circles (7 and 8, Fig. 7) may
be dialed to the coordinates of a specific celestial object, which
may then be located without a visual search. However, before
you can make use of the telescope's setting circles to locate
celestial objects, your telescope must first be polar aligned.
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