Celestron OMNI XLT 102 manual

O O m m n n i i X X L L T T S S e e r r i i e e s s T T e e l l e e s s c c o o p p e e s s 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 ● ● O O m m n n i i X X L L T T 1 1 0 0 2 2 ● ● O O m m n n i i X X L L T T 1 1 0 0 2 2 E E D D ● ● O O m m n n i i X X L L T T 1 1 2 2 0 0 ● ● O O m m n n i i X X L L T T 1 [...]

2 T T a a b b l l e e o o f f C C o o n n t t e e n n t t s s INTRODUCTION ................................................................................................................... ....................................... 4 Warning .............................................................................................................[...]

3 Transparency ................................................................................................................... ......................... 33 Sky Illumination ............................................................................................................... ........................ 33 Seeing ..........................[...]

- 4 - Congratulati ons on your purc hase of an Omni XLT Se ries telescope. The Omni XLT Series of tel escopes come in several differe nt models: 102mm refracto r, 102mm ED refractor, 120 mm refractor, 15 0mm refractor, 150mm Newtonian, 127mm Schmidt-Cassegrain. The Omni Series is made of the h ighest quality materials to ensure stability and durabi[...]

- 5 - Figure 1-1 Omni XLT 102 Refractor (Omni XLT 102ED, Omni XLT 120 and Om ni XLT 150R refractors are similar) 1. Optical Tube 7. 1.75" Steel Tr ipod 2. Tube Rings 8. Accessory Tray/ Leg Brace 3. Finderscope 9. Counterweights 4. Eyepiece 10. Counterweight Bar 5. Equatorial Mount 11. Dovetail Slide Bar 6. Latitude Adjustment Screw 12. Objecti[...]

- 6 - Figure 1-2 Omni XLT 150 Newtonian 1. Finderscope 7. 1.75" Steel Tr ipod 2. Finderscope Bracket 8. Accessory Tray/ Leg Brace 3. Focuser 9. Counterweights 4. Eyepiece 10. Counterweight Bar 5. Tube Rings 11. Dovetail Slide Bar 6. Equatorial Mount 12. Optical Tube 1 2 4 5 6 7 8 9 10 11 12 3[...]

- 7 - Figure 1-3 Omni XLT 127 Schmidt-Cassegrain 1. Optical Tube 7. 1.75" Steel Tr ipod 2. Finderscope 8. Counterweights 3. Finderscope Bracket 9. Counterweight Bar 4. Equatorial Mount 10. Declination Setting Circle 5. Latitude Scale 11. Dovetail Slide Bar 6. Accessory Tray/ Leg Brace 12. Schmidt Corrector Lens 1 2 3 4 6 7 8 9 10 11 12 5[...]

- 8 - This section covers the asse mbly instructions for your Celestron Omni XLT telesc ope. The equatorial m ount is exactly the same for all the Omni telescope models an d the optical tubes have some differences which will be no ted. Your Omni telescope should be set up indoor the first time so that it is easy to identify the various parts and fa[...]

- 9 - A A t t t t a a c c h h i i n n g g t t h h e e E E q q u u a a t t o o r r i i a a l l M M o o u u n n t t The equatorial m ount allows you to tilt the telescope’s axis of rotation s o that you can tr ack the sta rs as they move across the sky . The Om ni mount is a German e quatorial m ount that attaches to the tripod head. On one side of[...]

- 10 - A A t t t t a a c c h h i i n n g g t t h h e e C C e e n n t t e e r r L L e e g g B B r r a a c c e e Figure 2-6 1. Remove the ac cessory tray knob an d washer from the central rod. 2. Slide the accessory tray over the central rod so th at each arm of the tray is pushi ng against the inside of the tripod legs. 3. Thread the accessory tray [...]

- 11 - Since the fully assembled telescope can be quite he avy, position the mount so tha t the polar axis is poin ting towards north before the tube ass embly and counterweights are a ttached. This will make the polar alignment procedure much easier. I I n n s s t t a a l l l l i i n n g g t t h h e e C C o o u u n n t t e e r r w w e e i i g g h [...]

- 12 - 5. The DEC slow motion knob attaches in the same manner as the R.A. kn ob. The shaft that the DEC slow motion kn ob fits ove r is toward t he top of th e mount, just b elow the telesc ope mounti ng platform . Once agai n, you have tw o shafts to c hoose from . Use the shaft t hat is pointing toward the ground. This makes it easy to reach whi[...]

- 13 - I I n n s s t t a a l l l l i i n n g g t t h h e e F F i i n n d d e e r r s s c c o o p p e e To install the findersco pe onto the telescope y ou must first mount t he finderscope th rough the finder bracket and then attach it to the telescop e. Toward the rear of th e telescope tube (on refr actors and Schmidt-Cassegrain) and front of the[...]

- 14 - I I n n s s t t a a l l l l i i n n g g t t h h e e S S t t a a r r D D i i a a g g o o n n a a l l The Star Diag onal is a prism that diverts the l ight at a right angle to the light path of refracto rs and Schmi dt- Cassegrain telescopes. This allows yo u to observe in positio ns that are physically m ore comfortable t han if you looked st[...]

- 15 - The refracting telescopes can use eyepieces and diagonals of a 2” barrel diameter. To use a 2” barrel eyepiece, the 1¼” eyepiece adapter must first be rem oved. To do this, si mply loosen th e two chrom e thumbs crews located around the focuser barrel (see figure 2-12) and remove the 1 ¼” adapter. Once remove d, a 2” eyepiece or [...]

- 16 - B B a a l l a a n n c c i i n n g g t t h h e e M M o o u u n n t t i i n n D D E E C C The telescope should also be balanced on the declination axis to prevent any sudd en motions when the DEC clamp (Fig 2-13) is released. To balance the telescope in DEC (all telescopes except the SCT): 1. Release the R. A. clamp and r otate the telesc ope [...]

- 17 - A A d d j j u u s s t t i i n n g g t t h h e e M M o o u u n n t t i i n n A A l l t t i i t t u u d d e e • To increase the latitude of the polar axis, tighten the rear latitude adjustment screw and loosen the front screw (if necessary). • To decrease the lat itude of the polar a xis, tighten the fr ont (under t he counterweight bar) l[...]

- 18 - A telescope is an instrument that co llects and focuses lig ht. The nature of the o ptical design determ ines how the light is foc used. Some t elescopes (know n as refractors) us e lenses and ot her telescope s, known as re flectors (Newtonians), use m irrors. Then, the Sc hmidt-Cassegrain te lescope uses both m irrors and lenses. Each opti[...]

- 19 - Figure 3-3 A A c c u u t t a a w w a a y y v v i i e e w w o o f f t t h h e e l l i i g g h h t t p p a a t t h h o o f f t t h h e e S S c c h h m m i i d d t t - - C C a a s s s s e e g g r r a a i i n n o o p p t t i i c c a a l l d d e e s s i i g g n n The Schmidt-Cas segrain optical system (Schmidt-Cass or SCT for short ) uses a combi[...]

- 20 - Actual image orientation as seen with the unaided eye Inverted image, no rmal with Newtonians and as viewed with eyepiece directl y in other scope s Reversed from left to right, as viewed using a Star Diagonal on a refractor or Sc hmidt-Cassegrain I I m m a a g g e e O O r r i i e e n n t t a a t t i i o o n n The image orientation changes d[...]

- 21 - A A l l i i g g n n i i n n g g t t h h e e F F i i n n d d e e r r s s c c o o p p e e Accurate alignment of the finder m akes it easy to find object s with the telescope , especially celestial objects. To make aligning the finder as ea sy as possible, t his procedure sho uld be done in the day time when it is easy to find and identify obje[...]

- 22 - D D e e t t e e r r m m i i n n i i n n g g F F i i e e l l d d o o f f V V i i e e w w Determining t he field of view is im portant if y ou want to get an idea of the angular size of the o bject you are observing. To calculate the a ctual field of view, divide th e apparent field of the eyepi ece (supplied by the eyepiece manufacture r) by [...]

23 Up to this point, this manual covered the assembly and basic operation of your telescope. However, to understand your telescope more thorou ghly, you need to know a little about the night sky. Th is section deals with observational astronomy in general and includes information on the night sky and polar alignment. T T h h e e C C e e l l e e s s[...]

24 M M o o t t i i o o n n o o f f t t h h e e S S t t a a r r s s The daily motion of the Sun across the sky is familiar to even the most casual observer. This daily trek is no t the Sun moving as early astro nomers thought, but the result of the Earth's rotation. The Earth 's rotation also causes the stars to do the same, scribing out a[...]

25 L L a a t t i i t t u u d d e e S S c c a a l l e e The easiest way to polar align a telescope is wi th a latitude scale. Unlike other m ethods that require you to find t he celestial pole by identifying cert ain stars near it, this m ethod works off of a known const ant to determine how high the polar axis should be pointed. The Om ni CG-4 moun[...]

26 Figure 4-4 Remember, while Polar aligning, DO NOT move the telescope in R.A. or DEC. You do not want to move the telescope itself, but the pol ar axis. The tele scope is used simply to s ee where the polar axis is pointing. Like the previous m ethod, thi s gets you close to the pole but not directly on it. The followi ng methods hel p improve yo[...]

27 P P o o l l a a r r A A l l i i g g n n m m e e n n t t i i n n t t h h e e S S o o u u t t h h e e r r n n H H e e m m i i s s p p h h e e r r e e Polar alignment to the South Celestial Pole (SCP) is a little more challenging due to the fact that there is no very bright star close to it like Polaris is in the NCP. There are various ways to pola[...]

28 Pointing at Sigma Octantis This method utilizes Sigma Octantis as a gui depost to the ce lestial pole. Since Sigm a Oc tantis is about 1° degree from the south celestial pole, y ou can simply poi nt the polar axi s of your tele scope at Sigma Octant is.. Although this is by no means pe rfect alignm ent, it does get you wit hin one degree . Unli[...]

29 D D e e c c l l i i n n a a t t i i o o n n D D r r i i f f t t M M e e t t h h o o d d o o f f P P o o l l a a r r A A l l i i g g n n m m e e n n t t This method of polar alignment allows you to get the most accurate alignment on the celestial pole and is required if you want to do lon g exposure deep-sky astr ophotography through the telesco [...]

30 A A l l i i g g n n i i n n g g t t h h e e R R . . A A . . S S e e t t t t i i n n g g C C i i r r c c l l e e Before you can use the setting circles to find obj ects in the sky you need to align the R.A. setting circle. The declination setting circle is aligned during the process of polar alignment. In order to align the R.A. setting circle, y[...]

31 8. Lock the R.A. clamp to pr event the telescope from s lipping in R.A. The telescop e will track in R.A. as long as the motor drive is op erating. 9. Look thro ugh the findersc ope to see if y ou have lo cate d the object and center the object in the finder. 10. Look in the main op tics and the object should be there. For some of the fa inter o[...]

32 With your telesco pe set up, you are ready to use it for obse rving. This sect ion covers visual observing hints for solar system and deep sky o bjects as well as genera l observing conditions which will affect your ability to observe. O O b b s s e e r r v v i i n n g g t t h h e e M M o o o o n n Often, it is temptin g to look at the Moon when[...]

33 O O b b s s e e r r v v i i n n g g t t h h e e S S u u n n Although overlo oked by many amateur astronomers, solar observatio n is both rewarding and fun. However, because the Sun is so bright, special preca utions must be taken when observing our st ar so as not to damage your eyes or your telescope. Never project an image of t he Sun th rough[...]

34 S S e e e e i i n n g g Seeing conditions refers to the stability of the atmosphe re and directly affe cts the amount of fine detail seen in extended objects. The air in our atm osphere acts as a lens whic h bends and di storts incomi ng light rays. The amount of bending depe nds on ai r density. Varying temperature la ye rs have different densi[...]

35 After looki ng at the nig ht sky for a while you m ay want t o try photogra phing it . Several f orms of phot ography are possible with your telescope , including terrest rial and celest ial photography . Both of these are discussed in moderate detail with eno ugh information to get you started. Topics include the accessories required and so me [...]

36 4. Set the shutter speed to the “B” setting and focus the lens to the infinity settin g. 5. Locate the area of the sky that you wa nt to photog raph and m ove the telescope so t hat it points in that direction. 6. Find a suitable guide star in the telescope eyepiece field of view. T h is is relatively easy since you can search a wide area wi[...]

37 2. Center the Moon in t he field of y our telesco pe. 3. Focus the telescope by turning the focus knob until the image is sharp. 4. Set the shutter speed to the appropriate setting (see table 6-1). 5. Trip the shutter using a ca ble release. 6. Advance the film and repeat the pr ocess. Lunar Phase ISO 50 ISO 100 ISO 200 ISO 400 Crescent 1/2 1/4 [...]

38 1. Find and center the desired tar get in the viewfinder of your camera. 2. Turn the focus knob until the image is as sh arp as possible. 3. Place the black card ove r the front of the telescope. 4. Release the shutter using a cable release. 5. Wait for t he vibratio n caused by rel easing the sh utter to di minish. Also , wait for a m oment of [...]

39 Note: Digital Cameras – follow the camera in struc tions on focusing and shutter data. 1. Polar align the telescope. For more information on polar aligning see the Polar Alignment section earlier in the manual. 2. Remove all visual accessories. 3. Thread the Radial Guider onto your telescope. 4. Thread the T- Ring onto the Radial Guider. 5. Mo[...]

40 C C C C D D I I m m a a g g i i n n g g f f o o r r D D e e e e p p S S k k y y O O b b j j e e c c t t s s Special cameras have bee n develope d for taking im ages of deep sky im ages. These have evolved over t he last several years to become much more economical and am ateurs can take fantast ic images. Several bo oks have been written on how [...]

41 While your telescope requires little main tenance, there are a few things to reme mber that will ensure yo ur telescope performs at it s best. Each opti cal design type has special collima tion instructions described below. C C a a r r e e a a n n d d C C l l e e a a n n i i n n g g o o f f t t h h e e O O p p t t i i c c s s Occasionally dust a[...]

42 Pick a bright star and center it in the field of t he telescope. Study the image of the star whil e racking it in and out of foc us usi ng an eyepiece that yields 30 to 60 power for every inch of aperture . If an unsymmetrical focus pattern is present, then collimat ion is necessary. (If the telescope is properly coll imated, the out of focus st[...]

43 Before you begin the co llimation process, be sure that you r telescope is in thermal equilibrium with the surroundings. Allow 45 minutes for the telescope to re ach equilibrium if you move between large temperature extremes. To verify collimation, view a star near th e zenith. Use a medium to high power ocular — 12mm to 6mm focal length. It i[...]

44 Perfect collimation will yield a star image very symmetrical j u st inside and outside of focus. In addition, perfect collimation delivers the optimal optical performance specifications that your telesco pe is built to achieve. If seeing (i.e., air steadiness) is turbulent, collimation is difficult to judge. Wait until a better night if it is tu[...]

45 Newtonian collimation views as seen thro ugh the focuser using the collimation cap Secondary mirror needs adjustment Primary mirror needs adjustment Secondary Mirror Primary Mirror Mirror Clip Both mirrors aligned with the collimating cap in the focuser. Both mirrors aligned wi th your eye looking into the focuser.[...]

46 Night Time Star Collimating After successfully completing daytime colli mation, night time star collimation can be done by closely adjusting the primary mi rror while the tel escope tube is on it s mount and point ing at a bright star. The t elescope should be set up at night and a star's image shoul d be studie d at medi um to high po wer [...]

47 When satisfied with the collimation, tigh ten the small locking screws. Take note of the direction the li ght appears to flare . For example, if it appears t o flare toward the three o'clock p osition in the field of view, then you must move whichever screw or com bination of collimation screws necessary to move the star’s image t oward t[...]

48 You will find that additional accessories for your Om ni telescope will enhance your viewing pleasure and expand the usefulness of your telescope. This is just a short listing of various accessories. Visit the Celestron website for com plete and detailed accessories available. Barlow Lens - A Barlow lens is a negative lens th at increases the fo[...]

49 Flashlight, Ni ght Vision - (# 935 88) - Celestron’s premium model for as tronomy, using two red LED's to preserve night vision better than red filters or other devices. Brightness is adju stable. It operates on a single 9 volt batte ry (incl uded). Diagonal 2" Mirro r (# 93519) - Celestron offers a 2" 90° M irror Dia gonal to [...]

50 Reducer/Corrector (# 94175) - This lens reduces the focal length of the SCT telescope b y 37%, making your Omni XLT127 a 788mm f/6.3 instrument. In addition, this unique lens also corrects inherent aberrations to produce crisp im ages all the way across the field when used visually. When used photographically, there is some vignettin g that prod[...]

51 Appendix A Technical Specifications Omni XLT Series 21088 21092 21090 21094 31057 11084 Omni XLT 102 Omni XLT 102ED Omni XLT 120 Omni XLT 150R Omni XLT 150 Omni XLT 127 Optical Design Refractor Refractor Refracto r Refractor Newtonian Schmidt-Cassegrain Aperture 102mm (4.0") 102mm (4.0") 120mm (4.7 ") 150mm (6.0") 150mm (6.0&[...]

52 A A p p p p e e n n d d i i x x B B - - G G l l o o s s s s a a r r y y o o f f T T e e r r m m s s A - Absolute Magnitude The apparent magnitude that a star w ould have if it were observ ed from a standard distance of 10 parsecs, or 32.6 light- years. The absolute magnitude of the Sun is 4.8, at a distance of 10 pa rsecs, it would just be visib[...]

53 F - Focal Length The distance between a lens (or mirror) and the point at which the im age of an object at infinity is brought to focus. The focal length divided by the aperture of the mirror or lens is termed the focal ratio. J - Jovian Planets Any of the four gas giant pl anets that are at a greater distance from the s un than the terrestr ial[...]

54 R - Reflector A telescope in which the light is collected b y means of a mirror. Resolution The minimum detectable angle an optical system can detect. Because of diffraction, th ere is a limit to the minimum angle , resolution. The l arger the aperture, the better th e resolution. Right Ascension: (RA) T he angular distance of a celestial object[...]

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61 C C e e l l e e s s t t r r o o n n T T w w o o Y Y e e a a r r W W a a r r r r a a n n t t y y A. Celestron warrants this telescope to be free from defects in materials and workmanship for two years. Celestron will repai r or replace such product or part thereof which, upon ins pection by Celestron, is found to be defective in m aterials or wor[...]

Celestron 2835 Columbia Street Torrance, CA 90503 U.S.A. Tel. (310) 328-9560 Fax. (310) 212 -5835 Website www.celestron.com Copyright 2008 Cele stron All rights reserved. (Products or instructions may change without notice or obligatio n.) Item # 21088-INST Rev. 02 Printed in China $10.00 08-08[...]