Your First Astronomical Observing Session; The Moon; Celestial Observing Tips; Magnification - Celestron 80LCM Manual

YOUR FIRST ASTRONOMICAL OBSERVING SESSION

THE MOON

Now you are ready to take your telescope out at night and do some real observing!
Let's start with the Moon The Moon takes about one month to go through a complete phase cycle, from new Moon to full Moon and back
again Try observing it at different points during this cycle
While you can observe the Moon any time it is visible in the sky, the best time to view it is from two days after a new Moon up to a few days
before a full Moon During this period, you will be able to see the most detail in craters and lunar mountain ranges Consult a calendar or moon
phase app to find out when the next new Moon will be
1 . With a clear view of the Moon, set up your telescope with the 25 mm eyepiece
2 . Turn on the finderscope and look through it to find the red dot
3 . Move the telescope until you can see the Moon through the finderscope's window and the red dot is centered on the Moon
4 . Look through the 25 mm eyepiece Gently turn the focus knobs to adjust the sharpness of the image
CONGRATULATIONS! YOU HAVE NOW OBSERVED YOUR FIRST CELESTIAL OBJECT!
You can view many other celestial objects, such as planets, star clusters and nebulae using this same basic technique

CELESTIAL OBSERVING TIPS

This section covers visual observing hints for both solar system and deep-sky objects as well as general observing
conditions which will affect your ability to observe

MAGNIFICATION

You can change the magnification of your telescope by simply changing eyepieces Both telescopes and eyepieces have focal lengths
that are measured in millimeters To calculate the magnification of a given telescope and eyepiece combination, take the focal length of
the telescope and divide it by the focal length of the eyepiece The resulting number is the magnification factor
For example, the 80LCM has a focal length of 900 mm Using the 25 mm eyepiece:
_________________________
Magnification =

FIELD OF VIEW

Determining the field of view is important if you want to get an idea of the angular size of the object you are observing To calculate the
actual field of view, divide the apparent field of the eyepiece (supplied by the eyepiece manufacturer) by the magnification it gives you
in the scope you are using Using the example in the previous section, we can determine the field of view using the same telescope and
25 mm eyepiece
Actual Field Of View =
26 I ENGLISH
Focal Length of Telescope
Focal Length of Eyepiece
Apparent Field of View of Eyepiece
________________________________
Magnification
900 mm
____________ = 36x
=
25 mm
45°
______ = 1 25 degrees of arc
=
36