Celestron C8-NGT manual

1 A A d d v v a a n n c c e e d d S S e e r r i i e e s s A A d d v v a a n n c c e e d d S S e e r r i i e e s s G G G T T T 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 C C 8 8 - - N N / / C C 8 8 - - N N G G T T ● ● C C 1 1 0 0 - - N N / / C C 1 1 0 0 - - N N[...]

2 INTROD UCTION ................................................................................................................... ................................................................................. 4 Warning ........................................................................................................................ .....[...]

3 TELESC OPE BAS ICS ............................................................................................................... ........................................................................... 29 Image Orie ntatio n .............................................................................................................. .......[...]

4 Congra tulations on your purcha se of the Cele stro n Adv ance d Series telesc ope (A ST)! The A dvanc ed Series of te lescope s com e in standard (non-c om puterized) a nd com puterized GT models. The A dvanced Series is made of the hig hest quality ma terials to ensure sta bility a nd durability . A ll this adds up t o a tele scope tha t giv es[...]

5 Fig 1 - 1 - The Advanced S eries Newtonian (C8-N Show n) 1 . Finderscope 7. 2" Steel Tripod 2. Finderscope Bracket 8. Center Leg Brace / Ac cess ory Tray 3. Eyepiece 9. Counterweights 4. Focuser 1 0. Counterweight Bar 5. Tube Rings 11 . Dovetail S lid e Bar 6. Latitud e Adju stment Lev er 1 2. Optica l Tub e 1 2 3 4 5 6 7 8 9 1 0 1 2 11[...]

6 Fig 1 -2 - Th e Ad vanced Serie s GT Newton ian (C8-NGT Shown) 1 . Finderscope 8. Center Leg Brace / Ac cess ory Tray 2. Finderscope Bracket 9. Counterweights 3. Eyepiece 1 0. Counterweight Bar 4. Focuser 11 . Dovetail S lid e Bar 5. Tube Rings 1 2. Optica l Tub e 6. Latitude Adjustment Lever 1 3. Hand Control 7. 2" Steel Tripod 1 4. R.A. Mo[...]

7 This se ctio n cove rs t he as sem bly in struc tio ns fo r your Cele st ron Ad vanc ed Se ries T el escop e ( AST). Your AST telescope should be set up indoo r the first time so that it is eas y to identify the various parts and familiarize yourse lf with the correct assem bly procedure before att empting i t outdoor. 31061 / 310 62 11047 / 110 [...]

8 1. Locate the azimuth adjustm ent screws on the equ atorial mount. 2. Retract the screws so they no longer extend into the azimuth housing on the mount. Do NOT rem ove the screws since they are needed later for polar alignm ent. 3. Hold the equ atorial moun t over the t ripod head so th at the azimu th housing is above th e metal peg. 4. Place th[...]

9 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 h t t Depending on which AST telescope y ou have, you will receive either two or three coun terweights. To install the count er weig ht( s): 1. O rient the mount so t hat t he c ounte rwe ig ht ba r po ints to war d the ground . 2. Remove the coun te[...]

10 The knob is a tension fit, so sliding it on holds it in place. As mentioned above, there are two R.A. shafts, one on either side of the m ount. It mak es no difference w hich shaft you use s ince both w ork the sam e. Use which ever one you fin d more convenient. If, after a f ew observing s essions, you find the R.A. slow motion knob is more ac[...]

11 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 findersc ope onto the telescope y ou must first moun t the finderscope throug h the finder brack et and then attach it to the telescope. To ward th e front of the telesco pe tube, near the focusing assembly, there is a small bracket wit[...]

12 the eyepiece out. You can replace it with another ocu lar. Eyepieces are commonly referred to by focal length which is printed on the eyepiece barrel. The longer the focal length (i.e., the larg er the number) the lower the eyepiece power and the shorter the focal length (i.e., the smaller the number) the higher the magnificatio n. Generally, yo[...]

13 5. Loosen the screws that hold the telesco pe tube inside the mounting rings and slide t he telescope either for wards or backwards until it remains stat ionary when the DEC clamp i s released. 6. Tighten the tube rin g screws firmly to hold the teles cope in place. Like the R.A. balance, these a re general bala nce instructions and will reduce [...]

14 For Advanced GT users, it may be helpful to remove the front latitude adjust ment screw completely. This will allow the mount to reach lower latitudes without the screw com ing into contact with the R .A. motor assem bly. To remove the latitude screw, first use the rear screw to raise the mount head all the way up. Then remove the front latitude[...]

15 The Adva nced Serie s GT , comp uter ized ver sio n of eac h te le scop e has a hand cont rol ler d esig ned to gi ve you ins tant access to all the fun ctions that your telescope has to off er. With automatic slewing to ov er 40,000 objects, an d common sense menu descriptions, ev en a beginner can master its variety of features in just a few o[...]

16 4. Catalog Keys: The Advanced Series has keys on the hand control to allow direct acce ss to each of the catalogs in its database. The han d control contains th e following catalogs in its database: Messie r – Complete list of all Messier objects. NGC – Complete list o f all the deep-sky obj ects in the Revis ed New General Catalog. Caldwell[...]

17 A A l l i i g g n n m m e e n n t t P P r r o o c c e e d d u u r r e e s s In order for the t elescope to accurately poi nt to objects in the sky, it mus t first be aligned to three known pos itions (stars) in the sky. With this information, the telescope can create a model of the sky, which it uses to lo cate any object wi th known coordin ate[...]

18 Note: If incorrect inf ormation is entered into the hand control, the UNDO button acts like a back space bu tton allowing the user to re- enter the correct data. A A u u t t o o A A l l i i g g n n Auto Align allows the telescope to automatically choose three stars (two on one side of the Meridian , and one on the opposite side) on which to alig[...]

19 NOTE: Although the te lescope al low s the user t o select the alignm ent stars, for be st all-sky pointing acc uracy it is still nece ssary to select t wo align ment stars on one side o f the Meridi an and t he third star on the oppo site sid e of the Merid ian. For this re aso n, the hand co ntrol w ill only display stars that ar e on the sa m[...]

20 O O b b j j e e c c t t C C a a t t a a l l o o g g Selectin g an Object Now that the telescope is prop erly align ed, you can choose an object from any of the catalogs in the telescope's extensive database. The h and control ha s a key (4) desig nated for each of the catalogs in its database . There are two ways to select objects f rom the[...]

21 Tour Mode The Advanced Series telescopes include a tour feature which automatically allo ws the user to choose from a list o f interesting obj ects based on the date and ti me in which you a re observing. The auto matic tour will display onl y those objects that are within your set filter limits (see Filter Limits in the Setup Procedures section[...]

22 1 = .5x 6 = 64x 2 = 1x (s idereal) 7 = .5º / sec 3 = 4x 8 = 2º / sec 4 = 8x 9 = 3º / sec 5 = 16x S S e e t t u u p p P P r r o o c c e e d d u u r r e e s s The Advanced G T contains many user def ined se tup functi ons designed to gi ve the user control ov er the tele scope's many adv anced features. All of th e setup and utility featur[...]

23 that is not included in the regular database. There are sev eral ways to save an object to memory depen ding on what type of object it is: GoTo Object: To go to any of the user defined objects stored in th e database, scroll dow n to either GoTo Sky Obj or Goto Land Obj an d enter the n umber of the object y ou wish to select and press ENTE R. T[...]

24 Note: Some of the databases contain thousan ds of objects, and can therefore take several minu tes to return the closest objects. Precise GoTo The Advanced Series telescopes have a precise g oto function that can assist in finding extremely faint objects and centering objects closer to th e center of the field of view for as trophotography and C[...]

25 example, if y ou are observing f rom a mountainous location where the horizon is partially obscured, y ou can set y our minimum altitude limit to read +20º . This will make sure that the hand control only displa ys objects that are higher in altitude than 20º . If you want to explore the entire object database, set the maximum altitude limit t[...]

26 in R.A. (azimuth) until it reaches t he point that the cables a re extended to their maximum. T hen by displaying the telescopes azimuth i n this p osition (b y looking at Get Alt-Az under the Utilities menu) you can determine the telescopes azimuth at its most extended position. Enter this azi muth reading for either the m aximum or minimum azi[...]

27 should be. Use the equatorial head latitude and azi muth adjustments to place P olaris in the center of the eyepiece. Do not use the direction buttons to position Po laris. Once Polaris is centered in the eyepiece p ress ENTER; the polar axis should then be po inted towards the North Celestia l Pole. Light Control – This feature allows y ou to[...]

28 EQ NO RT H EQ SO U T H OFF MOD E SIDEREA L SOLAR LU NAR RA TE TRA CKIN G VIEW TI M E-SIT E SET UP T IM E- SI T E AN TI -B AC KLA S H FI LT ER LIM IT S DIRECTIO N B UTTO NS GOTO APPROAC H AUTOGU ID E RAT E AZIMUTH L IMITS EAST/WEST FI L TERIN G SCOPE SETU P CALIBRA TE GOT O HOME POSITIO N POL AR ALI G N LIG HT CO NTROL FACTOR Y SETTI N G VER SI O[...]

29 A tele scope is an i nstrument tha t collec ts and foc uses light. T he nature of the optical design dete rmine s how the light is foc used. Some telesc opes, k nown a s ref ractors, use le nses. O ther tele scopes , known as r efl ectors , use m irrors . A Newtonian reflector uses a sing le concave mirror as its prim ary. Light enters the tube [...]

30 Actual i mage ori ent atio n as see n with the unaide d eye Upside- dow n i mage, as view ed thou gh a Newton ian tele scope F F o o c c u u s s i i n n g g To focus y our telescope, simply turn the f ocus knob located directly below the eyepiece h older. Turning the knob clockwise allows you to focus on an object that is farther th an the one y[...]

31 Focal Le ngth of Te lescope (mm) Magnif ication =  Fo cal Length o f Eyepiece (mm ) Let’s sa y, for exa mple, you are u sin g the 20 mm eyep iece. To deter mine the magnificat ion you simp ly divid e the focal lengt h o f your teles cope (t he C8-N f or example ha s a f ocal leng th of 1000m m) by the [...]

32 Up to this point, this m anual covered the asse mbly and bas ic opera tion of y our telescope. H owe ver, to unde rstan d your telescope m ore thoroughly, you n eed to kn ow a little about the nig ht sky . This sec tion deals w ith observa tional astronom y in g enera l and i ncludes inform ation on the nig ht sky and polar a lignm ent. T T h h [...]

33 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 acro ss the sky is familiar to e ven the m o st casual obse rver. T his daily trek is not t he Su n mov ing as e arly as tronome rs thought, b ut the result of the Eart h's rotation. T he Eart h's rotatio n als o caus es the s tars to do the sam[...]

34 Latitude Scales The ea siest way to polar alig n a te lescope is with a latitude scale . Unlike othe r me thods that require y ou to find the celes tial pole by identifying certa in stars nea r it, this me thod w orks of f of a know n cons tant to de term ine how high the polar ax is sho uld be pointe d. T he A dvanc ed Serie s mount c an be adj[...]

35 Remember, w hile Polar aligning, do NOT move the telescope i n R.A. or DEC. You do not w ant to move the telescope itself, but the pola r axis. The telesco pe is used si mply to see w here the polar ax is is pointing. Lik e the pre vious m ethod, t his gets y ou close to t he pole but not dir ectly on it. T he follow ing m ethods help im prove y[...]

36 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 m ethod of pola r alignm ent allows you to ge t the most ac curate alignm ent on the ce lestial pole and is re quired if you w ant to do long e xposure de ep-sky astrophotog raphy throug h t[...]

37 With y our tele scope s et up, y ou a re rea dy to use it for obs erving . T his se ction cov ers v isual obs erv ing hints for b oth solar sy stem and deep sky objects as we ll as general obse rving c onditions w hich will a ffec t 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 tem pting t[...]

38 For safe solar view ing, use a solar filter tha t reduces the inte nsity of the Sun' s light, m aking it sa fe to v iew. With a filter y ou can see sunspots a s they move across the sola r disk and f a culae, w hich are bright pa tches see n near the Sun' s edge. S S o o l l a a r r O O b b s s e e r r v v i i n n g g H H i i n n t t s[...]

39 distu rbances vary from ti me-to-ti me and place-to -place. The si ze of the air p arcels compared to your aperture determ ines the " seeing" quality . Under good se eing con ditions , fine de tail is visi ble on t he brighter planets like Jupiter and Mars , and s tars a re pi npoi nt im ages . Under p oor s eeing condit ions, imag es [...]

40 Afte r looking at the n ight sk y for a w hile y ou may want to try phot ographi ng it. Sever al f orms of phot ogra phy are possible w ith your teles cope, incl udi ng terr estria l and ce lestia l photogra phy . Both of the se ar e discus sed in m odera te detail with enough information to get you started . Topi cs include the accesso ries req[...]

41 6. Find a suitable guide star in the teles cope eyepiece field of view. This is relatively easy since you can search a wide area w ithout affecting th e area covered by y our camera lens. If you do not have an illuminated cross hair e yepiece for guiding, simply defocus your guide star until it fills most of the field of view. This makes it easy[...]

42 Lunar Phase ISO 50 ISO 1 00 ISO 200 ISO 400 Crescent 1/2 1/4 1/8 1/15 Quarter 1/15 1/30 1/60 1/125 Full 1/30 1/60 1/125 1/250 The ex posure tim es listed in table 7-1 should be use d as a starting point. Al ways make ex posures that ar e longe r and shorter tha n the r ecomm ended tim e. Also, ta ke a few photos at each shutter speed. This will [...]

43 A A u u t t o o G G u u i i d d i i n n g g The Advanced GT telescope has a des ignated auto gu iding port for use with a C CD autoguider. The diagram below may be useful when connecting the CCD camera cable to th e telescope and calibrating the autoguider. Note th at the four outputs are active-low, with internal pull-ups and are capable of s i[...]

44 While your te lescope re quires litt le mainte nance, the re are a few things to remem ber that w ill ensure y our telescope pe rform s a t its best. 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 Occasional ly, du st and /or moisture may bu ild up on th e mirrors of your t elesco pe. S pe[...]

45 If you have an eyepiece in the focuser, rem o ve it. Rack the focuser tube in completely, using the focusing kn obs, until its silver tube is no lo nger visible. You will be looking through the focuser at a reflection of the secondar y mirror, projected f rom the primary mirror. During this step, ignore th e silhouetted reflection from the prima[...]

46 Figure 8- 2 A co llimate d te le scope should appear as a symmet ric al r ing pa ttern simila r to the diffracti on disk se en her e. Night Time Star Collimati ng After successfully com pleting daytime collimation, night time star collim ation can be done by closely adjusting th e primary mirror while the telescope tube is o n its mount and poin[...]

47 IMPORTANT: After m aking the first, or each adjustm ent, it is necessary to re- aim the telescope tube to re-cen ter the star ag ain in the center of the f ield of vi ew. The star image can then be judged f or symmetry by going just inside and outs ide of exact f ocus and noti ng the star' s pattern . Improvement sh ould be s een if the pro[...]

48 You will find that additional accessories en hance you r viewing ple asure and exp and the usefu lness of your telescop e. For ease of refe rence , all the accesso ries are listed i n alphab etical or der. Adapter A C (# 1877 3) - Allow DC (battery powe red) telescopes to be conv erted f or use with 1 20 v olt AC pow er. Auxiliary P ort Ac cesso[...]

49 Serie s 3 – #9 4119- 30 Lig ht Red, Blue , Gre en, ND50% T (#s 23A , 38A, 5 8, 96ND -50) Serie s 4 – #9 4119- 40 Yellow , Dee p Yellow , Violet, Pale Blue (#s 8, 47, 82A , 96ND- 13) Flash light , Night Visi on - (#93 588) - C eles tron’s pre mium model for as tronomy , using two red LE D ' s to preser ve ni ght vision better than re d[...]

50 RS-23 2 Ca ble (#939 20) – A llow s your Adv anced Se ries tele scope to be controll ed using a laptop c ompute r or PC. Once connect ed, the telesc ope ca n be c ontr olled using po pular as tronom y softwar e progr ams. Sk y Map s (#93722) - Celes tron Sky Maps are the ideal tea ching guide for le arning the night sky . You would n’t set o[...]

51 Appendix A – Technical Specifications Advanced Series 3 1 06 1 / 3 1 062 11 047 / 11 048 C8 -N C 1 0-N Specificati ons: Optical Design 200mm (8.0 ") reflector 2 54mm (10") reflector Focal Length 1000mm F/5 Pa rabola 1200m m F/4.7 Pa rabola Finderscope 9x50 9 x50 Mount CG-5 Equat orial CG-5 Equatoria l Eyepie ce 20mm - 1.25" (50x[...]

52 Appendix B - Glossar y of Terms A - Absolute mag nitude The appa rent m ag nitude that a s ta r would have if it w ere obs erve d from a sta ndard dista nce of 10 parsecs , or 32.6 light-y ears. The a bsolute m agnitude of the Sun is 4.8. a t a dis tance of 10 pa rsecs , it would jus t be v isible on Ea rth on a clea r moonles s night a way from[...]

53 J - Jovian P lan ets Any of the four gas gian t pl anets that are at a greater di stance for m the sun th an the terrestrial planet s. K - Kuiper Be lt A reg ion bey ond the orbit of Ne ptune ex tendi ng to a bout 100 0 AU w hich is a source of many short period c ome ts. L - Light-Year (LY ) A light- year is th e dist ance light traverses in a [...]

54 telescop e at thi s rate. The rate is 15 arc seconds p er second or 15 degrees per h our. T - Ter mina to r The bo unda ry line betwe en the lig ht and da rk por tion of the m oon or a pla net. U - Univers e The tota lity of as tronomic al things, e vents, re lations an d energ ies c apable of being de scribe d object ively. V - Variab le Star A[...]

55 A A P P P P E E N N D D I I X X C C L L O O N N G G I I T T U U D D E E S S A A N N D D L L A A T T I I T T U U D D E E S S LONGITUDE LA TITU DE degrees mi n degrees mi n AL AB AM A Anniston 85 51 33 34.8 Auburn 85 26.4 32 40.2 Birmingham 86 45 33 34.2 Centrevil le 87 15 32 54 Dothan 85 27 31 19.2 Fort Rucker 85 43.2 31 16.8 Gadsden 86 5.4 33 58[...]

56 LONGITUDE LA TITU DE degrees mi n degrees mi n Melbourne 80 37.8 28 6 Miami 80 16.8 25 49.2 Naples 81 4.8 26 7.8 Nasa Shuttle 80 40.8 28 37.2 Orlando 81 19.2 28 25.8 Panam a City 85 40.8 30 12 Patrick AFB 80 3.6 28 13.8 Pensacola 87 19.2 30 21 Ruskin 82 3.6 27 58.2 Saint Peters 82 40.8 27 55.2 Sanford 81 15 28 46.8 Sarasota 82 33 27 24 Tallahass[...]

57 LONGITUDE LA TITU DE degrees mi n degrees mi n Wurtsmith 83 2.4 44 27 Ypsilanti 83 31.8 42 13.8 MINNESOTA Albert Lea 93 22.2 43 40.8 Alexandria 95 22.8 45 52.2 Bemidji M uni 94 55.8 47 30 Brainerd-C rw 94 7.8 46 24 Detroit Laks 95 52.8 46 49.2 Duluth 92 10.8 46 49.8 Ely 91 49.2 47 54 Fairmont 94 25.2 43 39 Fergus Falls 96 4.2 46 18 Grand Rapids [...]

58 LONGITUDE LA TITU DE degrees mi n degrees mi n OKLAHOMA Altus AFB 99 16.2 34 40.2 Ardm ore 97 1.2 34 18 Bartlesville 96 0 36 45 Clinton 99 1.2 35 21 Enid 97 4.8 36 22.8 Fort Sill 98 2.4 34 39 Gage 99 46.2 36 18 Hobart 99 3 35 0 Lawton 98 25.2 34 34.2 Mcalester 95 46.8 34 52.8 Norm an 97 28.2 35 13.8 Oklahoma 97 3.6 35 24 Page 94 37.2 34 40.8 Pon[...]

59 LONGITUDE LA TITU DE degrees mi n degrees mi n Walla Walla 118 16.8 46 6 Wenatchee 120 1.2 47 24 Whidbey Is 122 39 48 21 Yakima 120 31.8 46 34.2 WEST VIRGINIA Beckley 81 7.2 37 46.8 Bluefield 81 13.2 37 18 Charleston 81 3.6 38 22.2 Clarksburg 80 13.8 39 16.8 Elkins 79 51 38 52.8 Huntington 82 33 38 22.2 Lewisburg 80 2.4 37 52.2 Martinsburg 77 58[...]

60 Appendix D - RS -232 Connecti on You can control you r telesco pe with a comput er via the RS -232 port on the compu terized h and contro l and usin g an optional R S-232 cable ( #93920 ). Onc e conne cted, the teles cope c an be contr olled using popular a str onomy so ftwa re progra ms . Communication Protocol: The Advanced GT commun icates at[...]

61 Additional RS23 2 Comma nds S S e e n n d d A A n n y y T T r r a a c c k k R R a a t t e e T T h h r r o o u u g g h h R R S S 2 2 3 3 2 2 T T o o T T h h e e H H a a n n d d C C o o n n t t r r o o l l 1. Multiply the desi red tracking rate (arcseconds/ second) by 4. Ex ample: if the desired track rate is 150 arcseconds/s econd, then TRACKRA T[...]

62 A PPENDIX E – MAPS OF T IME ZONES[...]

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70 CELESTRON TWO YEAR WAR RANTY A. Celestr on w arrants th is te le scope to be f ree f rom de fects in mate rial s and wor kmans hip f or tw o years. Cele stro n w ill re pa ir o r repl ace s uch prod uct o r part t her eo f which, upo n inspectio n by Celes tron, is found to be de fe ctive in m ater ials or workmans hip . As a con di tion to t he[...]

Celestro n 2835 Colu mbi a Street Torrance, CA 90503 U.S.A . Tel. (310) 3 28-956 0 Fax. (310) 2 12-583 5 Web site at http//www.celestron.co m Copyri ght 2003 C elest ron All rights reserved. (Products or in structions may chang e without notice or obligation.) Item # 3106 1-INS T Printed in China $10.00 09-03[...]