Meade LNT Instruction Manual download pdf (Page 49)

Note that the R.A.

circle is double-indexed (i.e., there are two series of numbers running in

opposite directions around the circumf

erence of the R.A. circle). The upper series of numbers

(increasing counterclockwise) applies to observers located in the Earth’s Northern Hemisphere;

the lower series of numbers (increasing clockwise) applies to observers located in the Earth’s

Southern Hemisphere.

To use the setting circles to locate an object not easily found by direct visual observa-

tion:

With the telescope aligned to the Celestial Pole, first look up the celestial coordinates (R.A. and

Dec.) of the object in a star atlas. Then loosen the R.A. lock and turn the telescope to read the

correct R.A. of the desired object; lock the R.A. lock onto the object. Next, turn the telescope in

Declination to read the correct Declination of the object. If the procedure has been followed

carefully, and if the telescope was well-aligned with the pole, the desired object should now be

in the telescopic field of a low-power eyepiece.

If you do not immediately see the object you are seeking, try searching the adjacent sky area.

Keep in mind that, with the 26mm eyepiece, the field of view of the LX90 is about 0.5°. Because

of its much wider field, the viewfinder may be of significant assistance in locating and centering

objects, after the setting circles have been used to locate the approximate position of the object.

Pinpoint application of the setting circles requires that the telescope be precisely aligned with

the pole See "LOCATING THE CELESTIAL POLE," page 46.

EQUATORIAL WEDGE

An optional equatorial wedge allows a more precise Polar alignment. Polar alignment allows

you to take longer exposure photographs with your LX90.

The LX90 requires an adapter to attach the equatorial wedge to the tripod. See the instruction

sheet supplied with the wedge for installation.

Equatorial Wedge

The equatorial wedge permits use in an astronomical, or “equatorial,” mode.The wedge fits onto

the field tripod.

NOTE: The Meade equatorial wedge is designed solely for use in conjunction with

the Meade field tripod. The wedge should never be used without the field tripod

(e.g., by placing the wedge alone on a table top and then mounting the telescope

on the wedge – the wedge may become seriously imbalanced, to the point where

the telescope may actually tip over.

Included features:

• Attachment of the wedge to the field tripod by means of only one manual knob.

• Quick azimuth adjustment by loosening the manual knob as described above.

• Bubble level for rapid tripod/wedge leveling.

• Etched latitude scale for fast adjustment of the latitude angle.

Lining Up with the Celestial Pole

Objects in the sky appear to revolve around the celestial pole. (Actually, celestial objects are

essentially “fixed.” Their apparent motion is caused by the Earth’s rotation). During any 24 hour

period, stars make one complete revolution about the pole, making concentric circles with the

pole at the center. By lining up the telescope’s polar axis with the North Celestial Pole (or for

observers located in Earth’s Southern Hemisphere, with the South Celestial Pole),

astronomical objects ma

y be followed, or tracked, simply by moving the telescope about one

axis, the polar axis. This tracking may be accomplished automatically with the

LX90 electric

motor dr

If the telescope is reasonab

ly well aligned with the pole, very little use of the telescope’s

Declination slo

w motion control is necessar

Vir

tually all of the required telescope tr

acking will

be in Right Ascension.

(If the telescope w

ere perf

ectly aligned with the pole, no Declination

acking of celestial objects would be required.) For the purposes of casual telescopic

observations, lining up the telescope’s polar axis to within a degree or two of the pole is more

than sufficient:

With this le

el of pointing accur

acy

, the telescope’

s motor drive will track accu-

ately and k

eep objects in the telescopic field of vie

w f

or perhaps 20 to 30 minutes.

Fig. 30: Section of Right

Ascension Setting Circle.

Fig. 31: Section of

Declination Setting Circle.

Fig. 32a: Equatorial Wedge.

Fig. 32b: LX90 mounted on

an equator

ial w

edge

1 2 ... 44 45 46 47 48 49 50 51 52 53 54 ... 59 60

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Meade LNT Instruction Manual Page 49

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