Celestron NexStar 102 GT 102x1000 AZ, Instruction Manual

COMPUTERIZED TELESCOPE

With your telescope set up, you are ready to use it for observing. 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. 

OBSERVING THE MOON

Often, it is tempting to look at the Moon when it is full. At this 
time, the face we see is fully illuminated and its light can be 
overpowering. In addition, little or no contrast can be seen dur-
ing this phase. 

One of the best times to observe the Moon is during its partial 
phases (around the time of first or third quarter). Long shad-
ows reveal a great amount of detail on the lunar surface. At low 
power you will be able to see most of the lunar disk at one time. 
Change to higher power (magnification) to focus in on a smaller 

area. Choose the lunar tracking rate from the NexStar’s 

MENU

 tracking rate options to keep the 

Moon centered in the eyepiece even at high magnifications. 

LUNAR OBSERVING HINTS

To increase contrast and bring out detail on the lunar surface, use eyepiece filters. A yellow filter 
works well at improving contrast while a neutral density or polarizing filter will reduce overall surface 
brightness and glare.

OBSERVING THE PLANETS

Other fascinating targets include the five naked eye planets. You 
can see Venus go through its lunar-like phases. Mars can reveal 
a host of surface detail and one, if not both, of its polar caps. 
You will be able to see the cloud belts of Jupiter and the great 
Red Spot (if it is visible at the time you are observing). In addi-
tion, you will also be able to see the Moons of Jupiter as they 
orbit the giant planet. Saturn, with its beautiful rings, is easily 
visible at moderate power. 

PLANETARY OBSERVING HINTS

Remember that atmospheric conditions are usually the limiting factor on how much planetary detail 
will be visible. So, avoid observing the planets when they are low on the horizon or when they are 
directly over a source of radiating heat, such as a rooftop or chimney. See the “Seeing Conditions” 
section later in this section.

To increase contrast and bring out detail on the planetary surface, try using Celestron eyepiece filters.

OBSERVING THE SUN

Although overlooked by many amateur astronomers, solar observation is both rewarding and fun. 
However, because the Sun is so bright, special precautions must be taken when observing our star 
so as not to damage your eyes or your telescope.

For safe solar viewing, use a safe solar filter to reduce the intensity of the Sun’s light, making it safe to 
view. Once you have located and focused the Sun, look for some of the following prominent features:

Sunspots

: Dark regions of the Sun’s photosphere which are cooler than the surrounding area.  

  Sunspots are usually seen to consist of two parts: the inner darker core, the umbra, and the  
  surrounding less dark region, the penumbra.

CELESTIAL OBSERVING

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