Z Z 76A 60A LT LT er ® ast roM Ast Ast roM ast er ® ® Series Telescopes INSTRUCTION MANUAL • AstroMaster ® LT 60AZ # 21073 • AstroMaster ® LT 70AZ # 21074 • AstroMaster ® LT 76AZ # 31036
TABLE OF CONTENTS INTRODUCTION • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • 3 ASSEMBLY • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • 6 Setting up the Tripod • • • • •
INTRODUCTION Congratulations on your purchase of an AstroMaster LT Series telescope. The AstroMaster LT Series of telescopes come in several different models and this manual covers three models mounted on the Alt-AZ Mount (an altazimuth is the simplest type of mount with two motions – altitude (up & down) and azimuth (side-to-side))-- 60mm refractor, 70mm refractor, and 76mm Newtonian. The AstroMaster LT Series is made of the highest quality materials to ensure stability and durability.
1 3 2 4 12 11 10 5 6 7 9 8 Figure 1-1 AstroMaster LT 70AZ Refractor (AstroMaster LT 60AZ refractor similar) 1. Objective Lens 2. Telescope Optical Tube 3. Star Pointer Finderscope 4. Eyepiece 5. Diagonal 6. Focus Knob 7. Pan Handle 8. Accessory Tray 9. Tripod 10. Azimuth Lock 11. Alt-Az Mount 12.
1 2 11 3 10 9 4 5 6 8 7 Figure 1-2 AstroMaster LT 76 AZ Newtonian 1. Star Pointer Finderscope 2. Eyepiece 3. Telescope Optical Tube 4. Primary Mirror 5. Pan Handle 6. Azimuth Lock 7. Accessory Tray 8. Tripod 9. Alt-Az Mount 10. Dovetail Mounting Bracket 11.
ASSEMBLY This section covers the assembly instructions for your AstroMaster LT telescope. Your telescope should be set up indoor the first time so that it is easy to identify the various parts and familiarize yourself with the correct assembly procedure before attempting it outdoor. Each AstroMaster LT comes in one box. The pieces in the box are – optical tube with attached sky pointer , Alt-Az mount with attached pan handle, 10 mm eyepiece – 1.25”, 20 mm eyepiece – 1.25”, mirror diagonal 1.
MOVING THE TELESCOPE MANUALLY The AstroMaster LT Alt-Az mount is easy to move wherever you want to point it. The up and down (altitude) is controlled by the pan handle (Figure 2-10). The side-to-side (azimuth) is controlled by the azimuth lock (Figure 2-9). The pan handle and the azimuth lock are both loosened by turning the handle and lock counterclockwise. When loose you can find your objects easily and then lock the controls. To lock the controls in place, turn them clockwise.
INSTALLING THE DIAGONAL & EYEPIECES ( REFRACTOR) The diagonal is a mirror assembly that diverts the light at a right angle to the light path of the refractor. This allows you to observe in a position that is more comfortable than if you looked straight through. Also, the diagonal can be rotated to any position which is most favorable for you. To install the diagonal and eyepieces: 1. Insert the small barrel of the diagonal into the 1.25” eyepiece adapter of the focus tube on the refractor – Figure 2-13.
TELESCOPE BASICS A telescope is an instrument that collects and focuses light. The nature of the optical design determines how the light is focused. Some telescopes, known as refractors, use lenses, .and other telescopes, known as reflectors (Newtonians), use mirrors. Developed in the early 1600s, the refractor is the oldest telescope design. It derives its name from the method it uses to focus incoming light rays.
IMAGE ORIENTATION The image orientation changes depending on how the eyepiece is inserted into the telescope. When using a star diagonal with refractors, the image is right-side-up, but reversed from left-to-right (i.e., mirror image). If inserting the eyepiece directly into the focuser of a refractor (i.e., without the diagonal), the image is upside-down and reversed from left-to-right (i.e., inverted).
To align the Star Pointer finderscope: 1. To turn on the Star Pointer, turn the switch to the “on” position – see Figure 3-4. 2. Locate a bright star or planet and center it in a low power eyepiece in the main telescope. 3. With both eyes open, look through the glass window at the alignment star. If the Star Pointer is perfectly aligned, you will see the red LED dot overlap the alignment star. If the Star Pointer is not aligned, take notice of where the red dot is relative to the bright star. Battery 4.
DETERMINING 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. In equation format, the formula looks like this: Apparent Field of Eyepiece True Field = Magnification As you can see, before determining the field of view, you must calculate the magnification.
ASTRONOMY BASICS Up to this point, this manual covered the assembly and basic operation of your telescope. However, to understand your telescope more thoroughly, you need to know a little about the night sky. This section deals with observational astronomy in general and includes information on the night sky and polar alignment. For telescopes with equatorial mounts, the users have setting circles and polar alignment methods to help them find objects in the sky.
MOTION OF THE STARS The daily motion of the Sun across the sky is familiar to even the most casual observer. This daily trek is not the Sun moving as early astronomers thought, but the result of the Earth’s rotation. The Earth’s rotation also causes the stars to do the same, scribing out a large circle as the Earth completes one rotation. The size of the circular path a star follows depends on where it is in the sky.
CELESTIAL OBSERVING 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 during this phase.
• • The best time to observe the Sun is in the early morning or late afternoon when the air is cooler. To center the Sun without looking into the eyepiece, watch the shadow of the telescope tube until it forms a circular shadow. OBSERVING DEEP SKY OBJECTS Deep-sky objects are simply those objects outside the boundaries of our solar system. They include star clusters, planetary nebulae, diffuse nebulae, double stars and other galaxies outside our own Milky Way.
Star hopping to the Andromeda Galaxy (M31) is a snap, since all the stars needed to do so are visible to the naked eye. Star hopping will take some getting used to and objects that don’t have stars near them that are visible to the naked eye are challenging. One such object is M57 (Figure 5-2), the famed Ring Nebula. Here’s how to find it: 1. Find the constellation of Lyra, a small parallelogram visible in the summer and fall months. Lyra is easy to pick out because it contains the bright star Vega. 2.
SEEING CONDITIONS Viewing conditions affect what you can see through your telescope during an observing session. Conditions include transparency, sky illumination, and seeing. Understanding viewing conditions and the effect they have on observing will help you get the most out of your telescope. Transparency Transparency is the clarity of the atmosphere which is affected by clouds, moisture, and other airborne particles.
ASTROPHOTOGRAPHY The AstroMaster LT series of telescopes was designed for visual observing. After looking at the night sky for a while you may want to try your hand at photography of it. There are several forms of photography possible with your telescope for celestial as well as terrestrial pursuits. Below is just a very brief discussion of some of the methods of photography available and suggest you search out various books for detailed information on the subject matter.
TELESCOPE MAINTENANCE While your telescope requires little maintenance, there are a few things to remember that will ensure your telescope performs at its best. CARE AND CLEANING OF THE OPTICS Occasionally, dust and/or moisture may build up on the objective lens or primary mirror depending on which type of telescope you have. Special care should be taken when cleaning any instrument so as not to damage the optics.
Aligning the Secondary Mirror The following describes the procedure for daytime collimation of your telescope using the optional Newtonian Collimation Tool (#94183) offered by Celestron. To collimate the telescope without the Collimation Tool, read the following section on night time star collimation. For very precise collimation, the optional Collimation Eyepiece 1 ¼” (# 94182) is offered. If you have an eyepiece in the focuser, remove it.
Night Time Star Collimating After successfully completing daytime collimation, night time star collimation can be done by closely adjusting the primary mirror while the telescope tube is on its mount and pointing at a bright star. The telescope should be set up at night and a star’s image should be studied at medium to high power (30-60 power per inch of aperture). If a non-symmetrical focus pattern is present, then it may be possible to correct this by re-collimating only the primary mirror.
Figure 7-2 Even though the star pattern appears the same on both sides of focus, they are asymmetric. The dark obstruction is skewed off to the left side of the diffraction pattern indicating poor collimation. When satisfied with the collimation, tighten the small locking screws. Take note of the direction the light appears to flare.
ASTROMASTER LT SPECIFICATIONS 21073 AM 60 AZ 21074 AM 70AZ 31036 AM 76 AZ Optical Design Aperture Focal Length Focal Ratio Secondary Mirror Obstruction -- Dia. - Area Optical Coatings Finderscope Diagonal Eyepieces 1.25” Apparent FOV -- 25 mm @ 50° -- 10 mm @ 40° Angular Field of View w/standard eyepiece Linear FOV w/standard eyepiece -ft/1000yds Refractor 60mm (2.4”) 700mm f/12 n/a Fully coated Star Pointer 1.25”Mirror Refractor 70mm (2.7”) 700mm f/10 n/a Fully coated Star Pointer 1.
2835 Columbia Street Torrance, CA 90503 U.S.A. Tel. (310) 328-9560 Fax. (310) 212-5835 Website www.celestron.com Copyright 2012 Celestron All rights reserved. (Products or instructions may change without notice or obligation.) Designed and intended for those 13 years of age and older WARNING: This product contains a chemical(s) known to the State of California to cause cancer, birth defects or other reproductive harm. Item # 21061-INST Printed in China $10.
