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CELESTIAL OBSERVING 

 
Now that your telescope is set up, you’re ready to use it for observing.  This section covers visual observing for both solar 
system and deep-sky objects.   
 

Observing the Moon 

 
In the night sky, the moon is a prime target for your first look because it is extremely bright and easy to find.  Although the 

beauty of the full moon may make it seem a perfect viewing object, in fact, the 
light reflected from its fully illuminated face can be overpowering.  In addition, 
little or no contrast can be seen during this phase. 
 
One of the best times to observe the moon is during its partial phases, such as a 
crescent or quarter moon.  At these times, long shadows reveal a great amount of 
detail on the lunar surface.  At low power, with the standard eyepiece, you’ll be 
able to see the whole lunar disk at one time.  Change to higher power 
(magnification) with an optional eyepiece to focus in on a smaller area.  Keep in 
mind that the rotation of the earth will cause the moon to drift out of your field of 
view.  You’ll have to manually adjust the telescope to keep the moon centered.  

This effect is more noticeable at higher power.  Consult a current astronomy magazine or your local newspaper to find out 
the current phase of the moon. 

 

Lunar Observing Hint 

 
To increase contrast and bring out visible detail on the lunar surface, try using different filters (available through your local 

Celestron

 dealer).  A yellow filter works well for improving contrast. 

 

Observing the Planets 

 
Other easy targets include the five “naked eye” planets of our solar system, so 
called because they can be spotted in the night sky by the unaided eye.  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’ll be able to see the cloud belts 
of

 Jupiter

, perhaps even the great Red Spot.  In addition, you’ll 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, as is

 Mercury

.  All you need to know 

is where to look.  Most astronomy publications indicate where the planets are in 
the sky each month. 
   

 

 
 
 
 
 
 
 
 

 

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Summary of Contents for FirstScope 90AZ

Page 1: ...F FI IR RS ST TS SC CO OP PE E 9 90 0 A AZ Z T TE EL LE ES SC CO OP PE E I I N N S S T T R R U U C C T T I I O O N N M M A A N N U U A A L L ...

Page 2: ... op pe e 9 90 0A AZ Z R R e e f f r r a a c c t t o o r r 1 Objective Lens 6 Erect Image Diagonal 2 Tube Rings 7 Focuser 3 Piggyback Camera Adapter 8 Slow Motion Cables 4 Star Pointer Finderscope 9 Tripod 5 Eyepiece 10 Eyepiece Accessory Tray 2 ...

Page 3: ...rtion of each of the three tripod legs down 6 8 Use the three tightening screws located at the bottom of each leg to secure the extended legs in place 3 Place the accessory tray on top of tripod s center leg brace Thread the tray s threaded post into the hole in the center of the leg brace 4 Slide the chrome end of each slow motion control cable onto the Alt Az mount gear shaft See Figure A 5 Remo...

Page 4: ... eye The star pointer is powered by a long life 3 volt lithium battery CR2032 located underneath the front portion of the Star Pointer Like all finderscopes the Star Pointer must be properly aligned with the main telescope before it can be used This is a simple process using the azimuth and altitude control knobs located on the side and bottom of the Star Pointer The alignment procedure is best do...

Page 5: ...n the azimuth tension knob Figure 5 on the right side of the mount Once loose point the telescope to the desired area and tighten the azimuth tension knob Figure 5 Azimuth tension knob For fine adjustments in azimuth turn the slow motion control knob on the left side of the mount Turning the knob clockwise moves the telescope to the right while turning it counterclockwise moves the telescope to th...

Page 6: ... telescope In most cases you will not be able to achieve a truly sharp focus In some cases you may actually see a double image Never look across or over objects producing heat waves This includes asphalt parking lots on hot summer days or building rooftops Hazy skies fog and mist can also make it difficult to focus when viewing terrestrially The amount of detail that can be seen under these condit...

Page 7: ...F Fi ie el ld d o of f V Vi ie ew w 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 In equation format the formula looks like this Apparent Field of Eyepiece True Field Magnification As y...

Page 8: ...se the moon to drift out of your field of view You ll have to manually adjust the telescope to keep the moon centered This effect is more noticeable at higher power Consult a current astronomy magazine or your local newspaper to find out the current phase of the moon Lunar Observing Hint To increase contrast and bring out visible detail on the lunar surface try using different filters available th...

Page 9: ...e transparency sky illumination and seeing Understanding viewing conditions and the affect they have on observing will help you get the most out of your telescope Transparency Transparency refers to the clarity of the atmosphere and is affected by clouds moisture dust and other airborne particles Thick cumulus clouds are completely opaque while cirrus clouds can be thin allowing light from the bri...

Page 10: ...he lower atmosphere most likely by heat waves from the ground or buildings To avoid the problems associated with Type 2 seeing select a good observing site Look for broad hilltops or open grassy fields Stable thermal conditions found near lakes and atmospheric inversions tend to produce good seeing Avoid sites that overlook asphalt parking lots plowed fields valleys or shorelines If you can t get ...

Page 11: ...AN NC CE E With proper care your telescope should rarely need any maintenance work A When not in use always replace all lens covers to keep dust and contaminants off the optical surfaces B A small amount of dust on any optical surface is ok If the dust builds up then use a can of compressed air and then a camel s hair brush to remove the dust C If the lens need cleaning it should be cleaned by a p...

Page 12: ...m X Cel This 6 element design allows each X Cel Eyepiece to have 20mm of eye relief 55 field of view and more than 25mm of lens aperture even with the 2 3mm In order to maintain razor sharp color corrected images across its 55 field of view extra low dispersion glass is used for the most highly curved optical elements The excellent refractive properties of these high grade optical elements make th...

Page 13: ...eaturing full color maps showing the positions of the stars throughout the year This useful guide also includes beautiful constellation paintings photographs and clear concise descriptions of stars the planets the sun the moon comets black holes galaxies and more Polarizing Filter Set 93608 The polarizing filter set limits the transmission of light to a specific plane thus increasing contrast betw...

Page 14: ...tion or deterioration due to normal wear is not covered by this warranty CELESTRON DISCLAIMS ANY WARRANTIES EXPRESS OR IMPLIED WHETHER OF MERCHANTABILITY OF FITNESS FOR A PARTICULAR USE EXCEPT AS EXPRESSLY SET FORTH HEREIN THE SOLE OBLIGATION OF CELESTRON UNDER THIS LIMITED WARRANTY SHALL BE TO REPAIR OR REPLACE THE COVERED PRODUCT IN ACCORDANCE WITH THE TERMS SET FORTH HEREIN CELESTRON EXPRESSLY ...

Page 15: ...nce CA 90503 U S A Tel 310 328 9560 Fax 310 212 5835 Web site at www celestron com Copyright 2004 Celestron All rights reserved Products or instructions may change without notice or obligation Item 21084 INST 10 00 01 05 Printed in China ...

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