Meade ETX Astro Telescope/ETX Spotting Scope Instruction Manual download pdf (Page 28)

Terrestrial Observing

The ETX-80AT makes an excellent high-resolution, terrestrial (land) telescope. Viewing terres-

trial objects requires looking along the Earth's surface through heat waves. These heat waves

often cause degradation of image quality. Low power eyepieces, like the MA 25mm eyepiece,

magnify these heat w

aves less than higher power eyepieces. Therefore, low power eyepieces

provide a steadier, higher quality image. If the image is fuzzy or ill-defined, reduce to a lower

wer eyepiece, where the heat waves do not have such an effect on image quality. Observing

in early morning hours, before the ground has built up internal heat, produces better viewing

conditions than during late afternoon hours.

Astronomical Observing

Used as an astronomical instrument, your telescope has many optical and electromechanical

capabilities. It is in astronomical applications where the high level of optical performance is

readily visible. The range of observable astronomical objects is, with minor qualification, limit-

ed only by the observer’s motivation.

Sidereal Rate

As the Earth rotates beneath the night sky, the stars appear to move from East to West. The

speed at which the stars move is called the sidereal rate.

If the telescope is aligned, the motor drive is designed to rotate the telescope at the sidereal

rate so that it automatically tracks the stars. This tracking makes it easy to locate objects and

keep them centered in the telescope’s eyepiece.

Alignment (Mount)

The telescope's mount permits the movement of the telescope in both Altitude (vertically) and

Azimuth (horizontally). In order to automatically track a celestial object, the mount must be

properly aligned. Easy Alignment is described on page 18.

Alt/Az Alignment

One-Star Alt/AZ Alignment or Two-Star Alt/AZ Alignment allows you to choose the alignment

stars during the alignment procedure. The stars are chosen from AutoStar’s database of align-

ment stars. The database displays after One-Star Alt/Az or Two-Star Alt/Az Alignment is select-

ed. .

The term "Alt/Az." is frequently used to refer to the Altitude or horizontal and Azimuth or verti-

cal movements of the ETX-80AT telescope. Other terms to describe a telescope's movement

may be used with telescopes that have mounts different from the ETX-80AT.

Alt/Az Home Position

To set your telescope in the "Alt/Az" home position ( Fig. 21).

• Loosen the telescope’s vertical lock (

13, Fig. 1).

• Level the optical tube with the horizon. Move the optical tube until the pointer points

at appro

ximately

“0”

on the setting circle.

•

Tighten the v

tical loc

k to a "fir

m f

eel" only

• Unlock the horizontal lock (

14, Fig. 1) and turn the telescope horizontally until it points

Nor

th.

Re-loc

k the hor

ontal loc

• Remove the 45° prism and eyepiece from the rear cell port. It may interfere with the

alignment procedure. After alignment, you may replace the prism and eyepiece.

• Press ENTER.

ADVANCED FEATURES

North

Declination 

at 0˚

Pointer

Fig. 21: Alt/Az Home

Position.

1 2 ... 23 24 25 26 27 28 29 30 31 32 33 ... 43 44

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Meade ETX Astro Telescope/ETX Spotting Scope Instruction Manual Page 28

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