Observe The Moon; Terrestrial Observing; Etx90 Tips - Meade EXT90 Instruction Manual

the telescope up, down, right, or left.
4. Press a Number key (Pg. 20, Fig. 10, 6) to
change the telescope's slew speed. See Slew
Speeds, on pg 20 for more information.
5. Use the viewfinder (Pg. 13, Fig. 3, 2) to locate an
object and practice using the AutoStar's Arrow
keys to center the object in the telescope's field
of view.
6. Use the telescope's focus knob (Pg. 13,
Fig. 3, 8) to bring the object into focus.

Observe the Moon

Point your telescope at the Moon (note that the Moon
is not visible every night) and practice using the Arrow
keys and the slew speeds to view different features.
The Moon contains many interesting features, including
craters, mountain ranges, and fault lines. The best time
to view the Moon is during its crescent or half phase.
Sunlight strikes the Moon at an angle during these
periods and adds a depth to the view. No shadows
are seen during a full Moon, causing the overly bright
surface to appear flat and rather uninteresting. Consider
the use of a neutral density Moon filter when observing
the Moon. Not only does it cut down the Moon's bright
glare, but it also enhances contrast, providing a more
dramatic image.

Terrestrial Observing

The ETX90 is an excellent high-resolution, terrestrial
(land) telescope. Viewing terrestrial objects requires
looking along the Earth's surface through heat waves.
These heat waves often cause degradation of image
quality. Lower power eyepieces, like the Super Plössl
26mm eyepiece, magnify these heat waves less than
higher power eyepieces. Therefore, lower power
eyepieces provide a steadier, higher quality image.
If the image is fuzzy or ill-defined, reduce to a lower
power 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.
If you wish to observe a distant land object, such as a
mountain top or a bird, you want to use your telescope
in its Terrestrial Observing mode. To start up the
telescope in Terrestrial mode:
1. Turn on the telescope.
2. Move your telescope using the direction arrows
on the handbox while looking through the Red-
Dot Finder to put your target in the eyepiece.
3. Focus on the target with the focus knob (pg. 13,
Fig. 3, 8).

ETX90 TIPS

Observing Considerations
• Try to pick an observing site away from street
and house lights and car headlights. While
this is not always possible, the darker the site,
the better.
• Try not to use a standard flashlight.
Experienced observers
flashlights, the red utility light on the AutoStar
#497 handbox, or tape red cellophane over
their flashlights to use for setup and map
reading so they don't have to continually
readjust their eyes to the darkness. Be
careful not to shine bright lights if there are
other observers in the area. Do not shine a
flashlight into the telescope while someone is
observing!
• Dress warmly. It gets chilly when you're sitting
for prolonged periods.
• Practice setting up your equipment during the
day or in a lighted area to become familiar
with it before going to a dark site.
• Use your 26mm eyepiece to view terrestrial
objects and wider areas of space, such as
open star clusters. Use optional higher power
eyepieces, such as a 9mm eyepiece, when
you wish to view something up close, such as
craters on the Moon or the rings of Saturn.
use red LED
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