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8" LX10 Schmidt-Cassegrain Telescope Instruction Manual
 C. ASTRONOMICAL OBSERVING
IMPORTANT NOTICE! Never use a telescope or spotting scope to look at the Sun! Observing the Sun, even for the shortest fraction of a second, will cause irreversible damage to your eye as well as physical damage to the telescope or spotting scope itself.
The LX10's wide range of high-performance standard features make this telescope an excellent observing tool for the serious amateur astronomer. The range of observable astronomical objects is, with minor qualification, limited only by the observer's motivation.

This section provides a basic introduction to the terminology associated with astronomy, and includes instructions for finding, following and photographing celestial objects.

[ toc ] Celestial Coordinates: Declination and Right Ascension

Celestial objects are mapped according to a coordinate system on the Celestial Sphere, the imaginary sphere on which all stars appear to be placed. This celestial object mapping system is analogous to the Earth-based coordinate system of latitude and longitude.

The poles of the celestial coordinate system are defined as those two points where the Earth's rotational axis, if extended to infinity, north and south, intersect the celestial sphere (Fig. 12). Thus, the North Celestial Pole is that point in the sky where an extension of the Earth's axis through the North Pole intersects the celestial sphere. This point in the sky is located near the North Star, Polaris.

In mapping the surface of the Earth, lines of longitude are drawn between the North and South Poles. Similarly, lines of latitude are drawn in an east-west direction, parallel to the Earth's Equator. The Celestial Equator is a projection of the Earth's Equator onto the celestial sphere.

Just as on the surface of the Earth, in mapping the celestial sphere imaginary lines have been drawn to form a coordinate grid. Thus, celestial object positions on the Earth's surface are specified by their latitude and longitude. For example, you could locate Los Angeles, California, by its latitude (34°) and longitude (118°); similarly, you could locate the constellation Ursa Major by its position on the celestial sphere:

R.A.: 11hr; Dec: +50°.

The celestial analog to Earth latitude is called Declination, or "Dec", and is measured in degrees, minutes and seconds (e.g., 15° 27' 33"). Declination shown as north of the celestial equator is indicated with a "+" sign in front of the measurement (e.g., the Declination of the North Celestial Pole is +90°), with Declination shown as south of the celestial equator indicated with a "-" sign (e.g., the Declination of the South Celestial Pole is -90°) (Fig. 12). Any point on the celestial equator itself (which, for example, passes through the constellations Orion, Virgo nd Aquarius) is specified as having a Declination of zero, shown as 0° 0' 0".

The celestial analog to Earth longitude is called "Right Ascension", or "R.A.", and is measured in time on the 24 hour "clock" and shown in hours ("hr"), minutes ("min") and seconds ("sec") from an arbitrarily defined "zero" line of Right Ascension passing through the constellation Pegasus. Right Ascension coordinates range from 0hr 0min 0sec to 23hr 59min 59sec. Thus there are 24 primary lines of R.A., located at 15 degree intervals along the celestial equator. Objects located further and further east of the prime Right Ascension grid line (0hr 0min 0sec) carry increasing R.A. coordinates.

All celestial objects are specified in position by their celestial coordinates of Right Ascension and Declination. The telescope's Dec and R.A. setting circles (8 and 9, Fig. 1) may be dialed to the coordinates of a specific celestial object, which may then be located without a visual search. However, before you can make use of the telescope's setting circles to locate celestial objects, your telescope must first be polar aligned.

[ toc ] Polar Alignment

With the telescope polar aligned two important telescope capabilities are enabled: (a) the motor drive permits the telescope to track any astronomical object, automatically; (b) the telescope's setting circles, discussed above, may be used to locate faint celestial objects directly from their catalogued coordinates.

Celestial objects are essentially fixed on the celestial sphere; however, they appear to move across the sky in an arc as the Earth rotates on its axis, with a complete rotation of the Earth occurring once in every 24 hour period. This apparent motion is not obvious to the unaided eye, but viewed through a telescope such as the LX10, this motion is rapid indeed. Objects centered in the telescope move entirely out of the field of view in 15 to 60 seconds, depending upon the magnification employed.

During the 24 hour period of the Earth's rotation, stars make one complete revolution about the Celestial Pole, making concentric circles with the Celestial Pole at the center. By lining up the telescope's polar axis with the North Celestial Pole (or South Celestial Pole if you are observing from the Earth's Southern Hemisphere), celestial objects may be followed (tracked) by moving the telescope about one axis, the polar axis.

The following polar alignment procedure assumes that the telescope has been set up on the Equatorial Wedge and LX10 Field Tripod, as shown in Fig. 1.

Figure 4

Polar alignment consists of the following two operations:

a. Setting the telescope's latitude angle, as read on the wedge's latitude scale (5, Fig. 4), so that the latitude scale reads the latitude of your observing location. Use the center of the hex-head screw (4, Fig. 4) as an indicator to read latitude angle.

CAUTION! Since the full weight of the telescope is resting on the tilt plate of the equatorial wedge, DO NOT loosen screws (4), Fig. 4, without FIRMLY holding the telescope by its fork arms with one hand while loosening the screws (4), Fig. 4 on each side of the wedge, with the other hand. Alternately, enlist the assistance of a second person for this purpose.

Look up the latitude of your observing location. (Most road maps show lines of latitude.) Then, keeping the precautionary note above in mind, loosen the screws (4), Fig. 4, on each side of the wedge, and move the telescope in latitude angle until the hex-head screw reads the latitude of your observing location.

b. Rotating the telescope-and-wedge as a unit on the tripod head until the telescope's polar axis (17), Fig. 1, points due-north.

Locating due-north by using Polaris, the North Star, is adequate for the purposes discussed here. Polaris can be found in relation to the Big Dipper by projecting a line from the so-called "pointer stars" of the Big Dipper, as shown in Fig. 14.

To rotate the telescope-and-wedge, loosen slightly the manual knob (6), Fig. 4; the telescope-and-wedge may then be rotated on top of the field tripod head. Note the telescope's polar axis, as shown in (17), Fig. 1.

Rotate the telescope-and-wedge until the telescope's polar axis points due-north; then re-tighten the manual knob (6), Fig. 4.

With (a) and (b) accomplished the telescope is sufficiently well polar aligned for all visual observing purposes, as well as for photography of the Moon and planets. Long-exposure astrophotography requires more precise polar alignment, a subject discussed in the section "Precise Polar Alignment," below.

With the level of pointing accuracy obtained by the above procedure the telescope's motor drive will accurately track and keep objects in the telescope's field of view for perhaps 20 to 30 minutes.

Once the latitude angle of the equatorial wedge has been set you will not need to realign the latitude angle of the equatorial wedge unless you move to a new observing site that is a considerable distance in latitude away from your original observing site; 70 miles of movement north or south is equivalent to only one degree in latitude change. Removing the equatorial wedge from the tripod will not affect the latitude setting.

After your have polar aligned your telescope for the first time, take a moment to check the calibration of the Declination setting circles (8, Fig. 1). This is accomplished by following these steps:

1. Center Polaris in the telescope's field of view.

2. Slightly loosen the central hub of each of the Declination setting circles. (One circle is on each fork arm.)

3. Use your finger to turn each setting circle until the dial reads 89.2°, the Declination of Polaris; then re-tighten the central hubs of each circle without moving the circle. The Declination setting circles are now calibrated.

[ toc ] Precise Polar Alignment

Precise polar alignment is essential for long-exposure astrophotography (typically defined as photo-exposures of 10 minutes or longer). Fewer tracking corrections are required during the duration of the exposure when the telescope is precisely polar aligned.

Precise polar alignment requires the use of a crosshair eyepiece, such as the Meade Illuminated Reticle Eyepiece, and a 2x Barlow lens for increased magnification (see Optional Accessories).

The method for precise polar alignment commonly referred to as the "drift" method is as follows:

1. Obtain a rough polar alignment as described above. Once approximate alignment has been accomplished, insert the 2x Barlow lens and the illuminated reticle eyepiece into the telescope's eyepiece holder.

2. With the motor drive running, point the telescope at a moderately bright star near where the meridian (the north-south line passing through your local zenith) and the celestial equator intersect. For best results, the star should be located within +/-30 minutes in R.A. of the meridian and within +/- 5° in Dec of the celestial equator. Pointing the telescope at a star that is straight up, and then moving the telescope in Dec to read 0° Dec, will point the telescope to the correct position.

3. Disregarding the drift in R.A., note the star's drift in Declination:

a. If the star drifts South (or down), the telescope's polar axis is pointing too far East (Fig. 15).

b. If the star drifts North (or up), the telescope's polar axis is pointing too far West (Fig. 16).

4. Move the wedge in azimuth (horizontal) to change the polar alignment. Reposition the east-west polar axis orientation until there is no further north-south drift by the star. Track the star for a period of time to be certain that its Declination drift has ceased.

5. Next, point the telescope at another moderately bright star near the Eastern horizon, but still near the celestial equator. For best results, the star should be about 20° or 30° above the Eastern horizon and within +/- 5° of the celestial equator (i.e., still at about 0° Dec).

6. Once again, note the star's drift in Declination:

a. If the star drifts South (or down), the telescope's polar axis is pointing too low (Fig. 17).

b. If the star drifts North (or up), the telescope's polar axis is pointing too high (Fig. 18).

7. Use the fine latitude adjustment on the equatorial wedge (7, Fig. 4) to change the latitude angle based on your observations above. Again, track the star for a period of time to verify that Declination drift has ceased.

After completing these procedures your telescope is precisely polar aligned, minimizing the need for tracking corrections during long-exposure astrophotography.

[ toc ] How to Locate Objects in the Night Sky

Now that your telescope is fully assembled and polar aligned, you are ready to begin observations.

Note that although the above assembly and polar alignment procedures may seem quite tedious, particularly if the LX10 is your first serious telescope, in fact, assembly and approximate polar alignment (accurate enough for visual observing) will quickly become routine. Once set, the latitude angle of the equatorial wedge need never be changed, unless you move your observing site a considerable distance in latitude, perhaps 150 miles or more.

For the beginning amateur astronomer, the simplest method of locating objects in the night sky, and an excellent way to learn how to operate your telescope, is to look at a celestial object you can clearly see with your own eyes.

Find the desired object in the viewfinder, center the object in the viewfinder's crosshairs, then observe through the main telescope's eyepiece and adjust the focus knob until the image is clear and sharp. With the motor drive turned on, observe how the telescope tracks, or follows, the object as it arcs across the sky. Turn the motor drive off for a few seconds, and note how rapidly the objects move through the field of view.

The position of celestial objects changes over the course of the year, so you should obtain a star chart, such as the Meade Star Charts, available from your Meade dealer, or refer to the monthly star chart presented in astronomy magazines, such as Sky & Telescope and Astronomy.

With these aids and with a little experience at the controls of the LX10, you will soon be exploring the surface of the Moon, the planets of our Solar System and the incredible assortment of star clusters, galaxies, and nebulae that lie beyond.

[ toc ] Setting Circles

Setting circles included with the LX10 permit the location of faint celestial objects not easily found by direct visual observation. Located on the top surface of the telescope's drive base, the R.A. circle (9), Fig. 1, is 8" in diameter. Declination circles (8), Fig. 1, are located at the top of each fork tine. With the telescope pointed at the North Celestial Pole, the Dec circle should read 90° (understood to mean +90°). Objects located below the 0-0 line of the Dec circle carry minus Declination coordinates. Each division of the Dec circle represents a 1° increment. The R.A. circle runs from 0hr to (but not including) 24hr, and reads in increments of 5min.

Note that the R.A. circle is double-indexed; i.e., there are two series of numbers running in opposite directions around the circumference of the R.A. circle. The outer series of numbers (increasing counterclockwise) applies to observers located in the Earth's Northern Hemisphere; the inner series of numbers (increasing clockwise) applies to observers located in the Earth's Southern Hemisphere.

To use the setting circles to locate an object not easily found by direct visual observation, please note as follows:

With the telescope aligned to the pole, center an object of known R.A. in the telescopic field. Then turn the R.A. circle, which can be rotated manually, until the R.A. coordinate of the object is correctly indicated by the R.A. pointer. As long as the telescope's motor drive remains "ON," the R.A. pointer will then correctly indicate the R.A. of any object at which the telescope is pointed throughout the duration of the observing session.

To locate a particular object, first look up the celestial coordinates (R.A. and Dec.) of the object in a star atlas. Then loosen the R.A. lock and turn the telescope to read the correct R.A. of the desired object; lock the R.A. lock onto the object. Next, turn the telescope in Declination to read the correct Declination of the object. If the procedure has been followed carefully, and if the telescope was well-aligned with the pole, the desired object should now be in the telescopic field of a low-power eyepiece.

If you do not immediately see the object you are seeking, try searching the adjacent sky area, using the R.A. and Dec. slow-motion controls to scan the surrounding region. Keep in mind that, with the 25mm eyepiece, the field of view of the LX10 is about 0.5°. Because of its much wider field, the viewfinder may be of significant assistance in locating and centering objects, after the setting circles have been used to locate the approximate position of the object.

Pinpoint application of the setting circles requires that the telescope be precisely aligned with the pole. Refer to the preceding section on "Precise Polar Alignment" for further details.

The setting circles may also be utilized in the absence of a power source for the motor drive. In this case, however, it is necessary to manually reset to the R.A. of the object you are observing just before going to the next object.

[ toc ] Observing Tips

To enjoy your LX10 to the fullest, follow these recommendations:

1. Always let the telescope "cool down" to the outside temperature before attempting to make serious observations. After moving the telescope from a warm house, the telescope's optics need about 15 to 20 minutes to adjust to the outside temperature before they will perform well.

2. Avoid setting up the telescope inside a room and observing through an open window (or worse, a closed window!). In such a case air currents caused by differences in indoor/outdoor temperatures make quality astronomical optical performance impossible.

Note: A practical exception to this rule is the case where your telescope is set up in a living room or den for observing an outdoor terrestrial scene or view through a closed window. At low powers (up to about 60X) the telescope will perform reasonably well in this application, but the observer should understand that the optical performance under these conditions cannot approach the performance that will be realized if the telescope were instead set up outside.

3. As discussed in "Magnifications" (Part 2), avoid "overpowering" your telescope. If the astronomical or terrestrial image becomes fuzzy at high powers, drop down to a lower power. Image degradation at high powers is not due to any fault of the telescope but is caused by heat waves and turbulence in the Earth's atmosphere. Astronomical observations at high powers (above 200X) should be undertaken only when the atmosphere is very steady, as confirmed by an absence of "twinkling" in star images.

4. Try not to touch the eyepiece when observing through the telescope. Vibrations in your hand are immediately transferred to the telescopic image.

5. If you wear eyeglasses and do not suffer from astigmatism, take your glasses off when using the telescope; the telescope's magnification compensates for near- or far-sightedness. Observers with astigmatism should, however, wear their glasses, since the telescope cannot compensate for this eye defect.

6. Allow your eyes to become "dark adapted" before attempting serious astronomical observations through the telescope. Night adaptation normally requires about 10 to 15 minutes.

7. As you use your LX10 more and more for astronomical observing, you will find that you are seeing finer and finer detail on the surface of Jupiter, for example. Observing through a fine optical instrument is to some degree an acquired skill. Celestial observing becomes increasingly rewarding as your eye becomes better trained in the detection of subtle variations of color, contrast, and resolution.

[ toc ] Using the LX10 for Astrophotography

As discussed earlier, the LX10 is well suited for the astrophotographer, facilitating both long-exposure guided photography or CCD imaging with its stable fork mounting, DC electronic worm-gear drive system, and hand controller.

Astrophotography of the Moon and planets with a 35mm SLR camera requires the optional #62 T-Adapter (Fig. 19).

Long-exposure, deep-space astrophotography of more than about 5 or 10 minutes' duration requires two telescope capabilities: (a) a means of monitoring the precise position of the object being photographed throughout the exposure, and (b) a means of changing the telescope's position very slightly to keep the object in exactly the same position throughout the exposure.

The Meade Off-Axis Guider and Illuminated Reticle Eyepiece, optional accessories fully described in the Meade General Catalog, fulfill the first requirement above. The LX10's standard-equipment hand controller, when equipped with the optional LX10 Electric Declination Motor, satisfies the second requirement. With the Electric Declination Motor attached, all four correction pushbuttons of the hand controller (N-S-E-W) are actuated, for precise dual-axis corrections during long-exposure astrophotography.

A few tips for basic astrophotography with the LX10:

1. The LX10 must be precisely polar aligned, as discussed above.

2. The tripod must be on a solid surface and the base of the equatorial wedge must be level.

3. Always use a cable-operated shutter release. Using the shutter release on the camera body may cause the camera to vibrate and blur your photograph.

4. Focus the image with extreme care. While observing the celestial object through the camera's viewfinder, turn the LX10's focus knob to achieve the sharpest possible focus, then open the camera's shutter to begin your exposure.

5. For terrestrial photography with the LX10, be aware that long distance photography is best accomplished in the early morning hours before heat waves begin to rise from the Earth's surface, and distort your photograph.

6. Astrophotography is an acquired skill; exercise patience and expect to waste a few rolls of film as you learn the techniques. The rewards of taking a quality astrophotograph, however, will make all your efforts worthwhile.

[ toc ] TERRESTRIAL OBSERVING

Although principally designed for astronomical observing, the LX10 makes an excellent terrestrial observing tool.

The telescope's controls are utilized in the same manner as for astronomical applications, but there are several significant differences in how you will locate and observe terrestrial subjects.

Image Orientation: The LX10's viewfinder presents an inverted image; what you see appears upside-down and reversed left-for-right.

With the standard-equipment diagonal prism and 25mm eyepiece in place in the main telescope, terrestrial images will appear right-side-up, but reversed left-for-right. This orientation is usually acceptable for terrestrial observing, except in the case of reading a distant sign or automobile license plate, for example.

Terrestrial image orientation can be fully corrected with the optional Meade #928 45° Erect-Image Diagonal Prism (see Optional Accessories).

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