ORION 10140 StarBlast 114mm Autotracker Instruction Manual
- June 6, 2024
- Orion
Table of Contents
INSTRUCTION MANUAL
Orion®StarBlast™114mm
AutoTracker™
#10140
Corporate Offices: 89 Hangar Way, Watsonville CA 95076 – the USA
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Customer Support: support@telescope.com
Copyright © 2021 Orion Telescopes & Binoculars. All Rights Reserved. No part
of this product instruction or any of its contents
maybe reproduced, copied, modified or adapted, without the prior written
consent of Orion Telescopes & Binoculars.
Introduction
Congratulations on your purchase of the Orion StarBlast telescope!
Take time to read through this manual before embarking on your journey through
the heavens.
Please read the separate AutoTracker Mount Manual (IN 489) for all information
relating to the mount and its accessories. Your StarBlast telescope is
designed to give you years of fun and exciting astronomical observations.
However, there are a few things to consider before using your telescope that
will ensure your safety and protect your equipment.
Parts List
Optical Tube Assembly
EZ Finder II Reflex Sight (with bracket)
Super 25mm Eyepiece
Super 10mm Eyepiece
Focuser Dust Cap
Telescope Dust Cap
Quick-Collimation Cap
Hex Key
The Eyepieces
The eyepiece, or ocular, is the optical element that magnifies the image
focused by the telescope. The eyepiece fits directly into the focuser.
The 1.25″ designation refers to the barrel diameter of the eyepieces. To
install one of the included eyepieces:
- Loosen the two thumbscrews on the eyepiece adapter at the end of the focuser drawtube and remove the protective dust cap.
- Slide the barrel of the eyepiece into the focuser.
- Tighten the thumbscrews to hold the eyepiece in place.
To remove the eyepiece, loosen the thumbscrews on the eyepiece adapter and
slide the eyepiece out. Eyepieces are commonly referred to by their focal
length and barrel diameter. The focal length of each eyepiece is typically
printed on the eyepiece body. For example this telescope ships with two 1.25″
diameter eyepieces; 25mm and 10mm. The longer the focal length (i.e., the
larger the number), the lower the eyepiece power or magnification; and the
shorter the focal length (i.e., the smaller the number), the higher the
magnification. Generally, you will use low-to-moderate power when viewing. For
more information on how to
determine power, see the section “Calculating Magnification.”
Focusing
Using the lower power eyepiece (25mm) inserted and secured with the
thumbscrews, aim the optical tube so the front end is pointing in the general
direction of an object at least 1/4-mile away. With your fingers, slowly
rotate one of the focus wheels until the object comes into sharp focus. A good
method to ensure you’ve hit the exact focus point is go a little bit beyond
sharp focus until the image starts to blur again, then reverse.
Figure 1. In the box: Parts of the StarBlast 114mm.
Figure 2. Insert the EZ Finder II in its dovetail base in the orientation shown and secure it with the thumbscrew.
WARNING:
- Never look directly at the Sun with the naked eye or with a telescope – unless you have a proper solar filter installed over the front of the telescope! Otherwise, permanent, irreversible eye damage may result.
- Never use your telescope to project an image of the Sun onto any surface. Internal heat build-up can damage the telescope and any accessories attached to it.
- Never use an eyepiece solar filter or a Herschel wedge. Internal heat build-up inside the telescope can cause these devices to crack or break, allowing unfiltered sunlight to pass through to the eye.
- Never leave the telescope unsupervised, either when children are present or adults who may not be familiar with the correct operating procedures of your telescope.
Figure 3. The EZ Finder II superimposes a tiny red dot on the sky, showing right where the telescope is aimed.
Figure 4. The EZ Finder II’s On/Off and adjustment knobs the rotation of the knob and stop when sharp focus has been achieved again.
Installing the EZ Finder II
Slide the base of the EZ Finder II bracket into the dovetail holder that is
pre-installed on the optical tube. The EZ Finder II should be oriented so that
the sight tube is facing the front of the telescope (Figure 2). Tighten the
thumbscrew on the dovetail holder to secure the EZ Finder II in place.
The EZ Finder II works by projecting a tiny red dot (it is not a laser beam)
onto a lens mounted in the front of the unit (Figure 3). When you look through
the EZ Finder II, the red dot will appear to float in space, helping you to
pinpoint your target object. The red dot is produced by a light-emitting diode
(LED) near the rear of the sight. A 3-volt lithium battery provides the power
for the diode.
NOTE: If it is present, remove the thin plastic battery shield tab (not
shown) from the battery compartment prior to use and discard it.
Turn the power knob (Figure 4) clockwise until you hear the “click” indicating
that power has been turned on. Look through the back of the reflex sight with
both eyes open to see the red dot. Position your eye at a comfortable distance
from the back of the sight. In daylight, you may need to cover the front of
the sight with your hand to be able to see the dot, which is purposefully
quite dim. The intensity of the dot is adjusted by turning the power knob. For
best results when stargazing, use the dimmest possible setting that allows you
to see the dot without difficulty. Typically a dimmer setting is used under
dark skies and a brighter setting is needed under light-polluted skies or in
daylight.
Aligning the EZ Finder II
For the EZ Finder II to work properly, it has to be aligned with the
telescope. When the two are aligned, a celestial object that is centered on
the EZ Finder II’s red dot should also appear in the center of the telescope’s
eyepiece. Alignment of the EZ Finder II is easiest during daylight, before
observing at night. Aim the telescope at a distant object such as a telephone
pole or roof chimney and center it in the telescope’s eyepiece. The object
should be at least 1/4 mile away. Now turn on the EZ Finder II and look
through it. Without moving the main telescope, use the EZ Finder II’s azimuth
(left/right) and altitude (up/down) adjustment knobs (Figure 4) to position
the red dot on the object in the eyepiece. When the red dot is centered on the
distant object, check to make sure that the object is still centered in the
telescope eyepiece. If it isn’t, re-center it and adjusts the EZ Finder II’s
alignment again. When the object is centered in the eyepiece and on the EZ
Finder’s red dot, the EZ Finder II is properly aligned with the telescope.
Once aligned, EZ Finder II will usually hold its alignment even after being
removed and remounted. Otherwise, only minimal realignment will be needed. At
the end of your observing session, be sure to turn off the power knob on the
EZ Finder II.
Replacing the EZ Finder II
Battery Should the battery ever die, replacement 3-volt lithium batteries are
available from many retail outlets. Remove the old battery by inserting a
small flat-head screwdriver into the slot on the battery casing (Figure 4) and
gently prying open the case. Then carefully pull back on the retaining clip
and remove the old battery. Do not over-bend the retaining clip. Then slide
the new battery under the battery lead with the positive (+) end facing down
and replace the battery casing.
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. Other telescopes, known as reflectors, use mirrors.
The StarBlast 114mm is a reflecting telescope with a primary and secondary
mirror to gather and focus light.
Focusing
Once you have found an object in the telescope, turn the focusing knob until
the image is sharp. To achieve a truly sharp focus, never look through glass
windows or across objects that produce heat waves, such as asphalt parking
lots.
For astronomical viewing, out-of-focus star images are very diffuse, making
them difficult to see. If you turn the focus knobtoo quickly, you can go right
through focus without seeing the image. To avoid this problem, your first
astronomical target should be a bright object (like the Moon or a planet) so
that the image is visible even when out of focus. It can even be helpful to
practice during the day on an object at least a mile away, i.e. at “infinity.”
Image Orientation
The image orientation of any telescope changes depending on its optical design
and how the eyepiece is inserted into the telescope. A refractor used with a
star diagonal, for astronomical viewing, will show an image that is right side
up, but left-right reversed. When observing through a reflector such as the
StarBlast 114mm, the image will appear upside down and backward. For this
reason, reflectors are not recommended for daytime terrestrial observing. But
since there is no “right side up” in space, a reflector is fine for
astronomical viewing.
Calculating Magnification
You can change the power of your telescope just by changing the eyepiece
(ocular). To determine the magnification of your telescope, simply divide the
focal length of the telescope by the focal length of the eyepiece used.
Magnification is calculated as follows:
Telescope Focal Length/Eyepiece Focal Length= Magnification
For example, the StarBlast 114mm has a focal length of 500mm, which when used
with the supplied 25mm eyepiece yields:
500mm/25mm= 20x
The magnification provided by the 10mm eyepiece is:
500mm/10mm= 50x
Although the power is variable, each instrument under average skies has a
limit to the highest useful magnification. Thegeneral rule is 2x per
millimeter of aperture. For example, the star last 114mm is so named for its
primary mirror, which has a diameter of 114mm. So 114mm x 2 = 228. Thus, 228x
is the highest magnification one can normally achieve under ideal seeing
conditions. Although this is the maximum useful magnification, most observing
will yield the best results at lower powers.
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/Magnification = True Field
As you can see, before determining the field of view, you must calculate the
magnification. Using the example in the previous section, we can determine the
field of view using the same 25mm eyepiece.
The 25mm eyepiece has an apparent field of view of 49°. Divide 49° by the
magnification, which is 20 power. This yields an actual field of view of
2.45°.
49/20= 2.45° True Field of view
The 10mm eyepiece has an apparent field of view of 52°. Divide 52° by the
magnification, which is 50 power. This yields an actual field of view of
1.04°.
52/50= 1.05° True Field of view
To convert degrees to feet at 1,000 yards, which is more useful for
terrestrial observing, simply multiply by 52.5.
The 25mm eyepiece produces a linear field width of 128.6 feet at a distance of
one thousand yards (2.45° X 52.5).
The 10mm eyepiece produces a linear field width of 54.6 feet at a distance of
one thousand yards (1.04° X 52.5).
General Observing Hints
When working with any optical instrument, there are a few things to
remember to ensure you get the best possible image:
- Never look through window glass. Glass found in household windows is optically imperfect, and as a result, may vary in thickness from one part of a window to the next. This inconsistency can and will affect the ability to focus your telescope. In most cases you will not be able to achieve a truly sharp image, while in some cases; you may actually see a double image.
- Never look across or over objects that are radiating 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. The amount of detail seen under these conditions is greatly reduced.
- If you wear corrective lenses (specifically, glasses), you may want to remove them when observing with an eyepiece attached to the telescope. When using a camera, however, you should always wear corrective lenses to ensure the sharpest possible focus. If you have astigmatism, corrective lenses must be worn at all times.
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 that 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.
One of the best times to observe the Moon is during its partial phases (at
crescent phases and around the time of the first or third quarter). Long
shadows reveal a great amount of detail on the lunar surface. At low power,
you will be able to see most of the lunar disk at one time. Change to higher
power (magnification) to focus in on a smaller area.
Lunar Observing Hints
- To increase contrast and bring out detail on the lunar surface, use eyepiece filters. A yellow filter works well at improving contrast while a neutral density or polarizing filter will reduce overall surface brightness and glare.
Observing the Planets
Other fascinating targets include the five naked-eye planets. 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 will be able to see the
cloud belts of Jupiter and the Great Red Spot (if it is visible at the time
you are observing). In addition, you will also 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.
Planetary Observing Hints
- Remember that atmospheric conditions are usually the limiting factor on how much planetary detail will be visible. So, avoid observing the planets when they are low on the horizon or when they are directly over a source of radiating heat, such as a rooftop or chimney. See the “Seeing” section later in this section.
- To increase contrast and bring out detail on the planetary surface, try using color eyepiece filters. Observing the Sun Although overlooked by many amateur astronomers, solar observation is both rewarding and fun. However, because the Sun is so bright, special precautions must be taken when observing our star so as not to damage your eyes or your telescope. Never project an image of the Sun through the telescope. Tremendous heat build-up may result inside the optical tube. This can damage the telescope and/or any accessories attached to the telescope. For safe solar viewing, use a solar filter that reduces the intensity of the Sun’s light, making it safe to view. With a filter, you can see sunspots as they move across the solar disk and faculae, which are bright patches seen near the Sun’s edge.
Solar Observing Hints
- 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. There are also special “solar viewing” finder devices available that are designed for aligning a telescope with the Sun.
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 Milky Way galaxy. Most
deep-sky objects have a large angular size. Therefore, low-to-moderate power
is all you need to see them. Visually, they are too faint to reveal any of the
color seen in long exposure photographs. Instead, they appear grayish. And,
because of their low surface brightness, they should be observed from a dark
sky location whenever possible. Light pollution around large urban areas
washes out most nebulae making them difficult, if not impossible, to observe.
Light Pollution Reduction filters help reduce the background sky brightness,
thus increasing the contrast.
Viewing 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. Thick cumulus clouds are completely
opaque while cirrus can be thin, allowing the light from the brightest stars
through. Hazy skies absorb more light than clear skies, making fainter objects
harder to see and reducing contrast on brighter objects. Aerosols ejected into
the upper atmosphere from volcanic eruptions also affect transparency. Ideal
conditions are when the night sky is inky black.
Sky Illumination
General sky brightening caused by the Moon, aurorae, natural airglow, and
light pollution greatly affects transparency. While not a problem for the
brighter stars and planets, bright skies reduce the contrast of extended
nebulae making them difficult, if not impossible, to see. To maximize your
observing, limit deep-sky viewing to moonless nights far from the light-
polluted skies found around major urban areas. LPR filters enhance deep-sky
viewing from light polluted areas by blocking unwanted light while
transmitting light from certain deep sky objects. You can, on the other hand,
observe planets and stars from light polluted areas or when the Moon is out,
due to their strong brightness.
Seeing
Seeing conditions refer to the stability of the atmosphere. “Seeing” directly
affects the amount of fine detail seen in extended objects. The air in our
atmosphere acts as a lens that bends and distorts incoming light rays. The
amount of bending depends on air density. Varying temperature layers have
different densities and, therefore, bend light differently. Light rays from
the same object arrive slightly displaced creating an imperfect or smeared
image. These atmospheric disturbances vary from time to time and place to
place. The size of the air parcels compared to your aperture determines the
“seeing” quality. Under good seeing conditions, fine detail is visible on the
brighter planets like Jupiter and Mars, and stars are pinpoint images. Under
poor seeing conditions, images are blurred and stars appear as blobs. The
conditions described here apply to both visual and photographic observations.
Telescope Maintenance
While your StarBlast 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
In general, your telescope’s mirrors will only need to be cleaned very
infrequently, if ever. Covering the front opening of the telescope with the
dust cover when it is not in use will prevent dust from accumulating on the
mirrors. Keeping the dust cap on the focuser’s 1.25″ opening is also a good
idea. Improper cleaning can scratch the mirror coatings, so the fewer times
you have to clean the mirrors, the better. A little dust or small specks of
paint from the scope’s interior have virtually no effect on the visual or
imaging performance of the telescope. So avoid the urge to clean the optics
unless it is absolutely necessary!
To clean the primary mirror, carefully remove the mirror cell from the
telescope. To do this, you must remove the screws that attach the mirror cell
to the steel tube. These screws are located on the outer edge of the mirror
cell. Then pull the cell away from the tube. Be careful not to touch the
aluminized surface of the mirror with your fingers. Set the mirror on a clean,
soft towel.
Fill a clean sink, free of abrasive cleanser, with room-temperature water, a
few drops of liquid dishwashing detergent, and if possible, a cap-full of
rubbing alcohol. Submerge the mirror (aluminized face up) in the water and let
it soak for several minutes (or hours if it is a very dirty mirror). Wipe the
mirror under water with clean cotton balls, using extremely light pressure and
stroking in straight lines across the surface. Use one ball for each wipe
across the mirror. Then rinse the mirror under a stream of lukewarm water. Any
particles on the surface can be swabbed gently with a series of clean cotton
balls, each used just one time. Dry the mirror in a stream of air (a “blower
bulb” works great), or remove any stray drops of water with the corner of a
paper towel. Dry the bottom and the edges with a towel (not the mirror
surface!). Leave the entire assembly in a warm area until it is completely
dry. Then reinstall the mirror cell in the telescope optical tube with the
screws.
To minimize the need to clean your telescope, replace all lens covers once you
have finished using it. This will prevent contaminants from entering the
optical tube.
Collimation
Collimation is the process of adjusting the telescope’s mirrors so they are
aligned with one another. Your telescope’s optics were aligned at the factory,
and should not need much adjustment unless the telescope was jarred while in
transit. Accurate mirror alignment is important to ensure the peak performance
of your telescope, so it should be checked regularly. Collimation is a
relatively easy process and can be done in daylight or darkness. To check
collimation, remove the eyepiece and look down the focuser drawtube. You
should see the secondary mirror centered in the drawtube, as well as the
reflection of the primary mirror centered in the secondary mirror, and the
reflection of the secondary mirror (and your eye) centered in the reflection.
Figure 5. Collimating the optics. (a) When the mirrors are properly
aligned, the view down the focuser’s drawtube should look like this. (b) Here,
the secondary mirror is centered under the focuser, but it needs to be
adjusted (tilted) so that the entire primary mirror is visible. (c) When the
mirror is correctly aligned, the center “dot” of the collimation cap will be
centered. of the primary mirror, as in Figure 5a. If anything is off-center,
proceed with the following collimating procedure.
The Collimation Cap
Your StarBlast comes with a “quick collimation cap”. This is a simple cap that
fits on the focuser’s drawtube like a dust cap but has a tiny hole in the
center and a reflective inner surface. The collimation cap helps center your
eye over the focuser drawtube so that aligning the optical components is
easier to achieve. The reflective surface provides a distinct visual reference
that is helpful in centering the mirror reflections. Figures 5b through 5c
assume that you have the collimation cap in place.
The Primary Mirror Center Mark
You’ll notice that the primary mirror of the StarBlast has a tiny ring
(sticker) marking its center. This “center mark” allows you to achieve very
precise collimation; you don’t have to guess where the exact center of the
mirror is.
Figure 6. Adjust the tilt of the secondary mirror with the three recessed setscrews surrounding the center screw.
Figure 7. A star test will determine if the telescope’s optics are
properly collimated. An unfocused view of a bright star through the eyepiece
should appear as illustrated on the right if the optics are perfectly
collimated. If the circle is unsymmetrical, as illustrated on the left, the
scope needs collimation.
NOTE: The center ring sticker need not ever be removed from the primary
mirror. Because it lies directly in the shadow of the secondary mirror, its
presence in no way adversely affects the optical performance of the telescope
or the image quality. That might seem counter-intuitive, but it’s true!
Preparing the Telescope for Collimation
Once you get the hang of collimating, you will be able to do it quickly even
in the dark. For now, it is best to collimate in daylight, preferably in a
brightly lit room and aimed at a white wall. It is recommended that the
telescope tube be oriented horizontally. This will prevent any parts from the
secondary mirror from falling down onto the primary mirror and causing damage
if something comes loose while you are making adjustments. Place a sheet of
white paper inside the optical tube directly opposite the focuser. The paper
will provide a bright “background” when viewing the focuser.
Aligning the Secondary Mirror
To adjust the secondary mirror collimation, you will need to use the included
hex key.
Adjusting the Secondary Mirror’s Tilt
The tilt of the secondary mirror may occasionally require adjustment. If the
entire primary mirror reflection is not visible in the secondary mirror when
using the collimation cap, as in Figure 5b, you will need to adjust the tilt
of the secondary mirror with the three recessed setscrews surrounding the
center screw (Figure 6). Using the hex key, first loosen one of the three
alignment set screws by, say, one full turn, and then tighten the other two to
take up the slack. The goal is to center the primary mirror reflection in the
secondary mirror, as in Figure 5c.
Aligning the Primary Mirror
The primary mirror of the StarBlast 114mm is fixed so no adjustments are
necessary. The view through the collimation cap should now resemble Figure 5c.
A simple star test will indicate how well the telescope optics are collimated.
Another even easier and more precise way to collimate your reflector is to use
a laser collimator such as the Orion LaserMate II Deluxe collimator (sold
separately). It comes with complete instructions and takes no more than a
couple of minutes to achieve dead-on collimation. We highly recommend it!
Star-Testing the Telescope
When it is dark, point the telescope at a bright star and accurately center it
in the eyepiece’s field of view. Slowly de-focus the image with the focusing
knob. If the telescope is correctly collimated, the expanding disk should be a
perfect circle (Figure 7). If the image is unsymmetrical, the scope is out of
collimation. The dark shadow cast by the secondary mirror should appear in the
very center of the out-of-focus circle, like the hole in a donut. If the
“hole” appears off-center, the telescope is out of collimation.
If you try the star test and the bright star you have selected is not
accurately centered in the eyepiece, the optics will always appear out of
collimation, even though they may be perfectly aligned. It is critical to keep
the star centered, so over time you may need to make slight corrections to the
telescope’s position in order to account for the sky’s apparent motion. A good
start to point at for a star test is Polaris, the North Star because its
position does not move significantly over time. You can do a star test on
Polaris without even turning on power to the scope.
Specifications
Primary Mirror:| 114mm diameter, parabolic, center
marked
---|---
Focal Length:| 500mm
Focal Ratio:| f/4.4
Focuser:| 1.25″ Rack and Pinion
Eyepieces:| Super 25mm, Super 10mm
Magnification with
supplied eyepieces:| 20x, 50x
Glossary of Terms
A
Absolute magnitude: The apparent magnitude that a star would have if it
were observed 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 parsecs, it would
just be visible on Earth on a clear moonless night away from surface light.
Airy disk: The apparent size of a star’s disk produced even by a perfect
optical system. Since the star can never be focused perfectly, 84 percent of
the light will concentrate into a single disk, and 16 percent into a system of
surrounding rings. Alt- Azimuth Mounting: A telescope mounting using two
independent rotation axes allowing movement of the instrument in Altitude and
Azimuth. Altitude: In astronomy, the altitude of a celestial object is its
Angular Distance above or below the celestial horizon.
Aperture: The diameter of a telescope’s primary lens or mirror; the
larger the aperture, the greater the telescope’s light-gathering power.
Apparent Magnitude : A measure of the relative brightness of a star or
other celestial object as perceived by an observer on Earth.
Arcminute: A unit of angular size equal to 1/60 of a degree.
Arcsecond: A unit of angular size equal to 1/3,600 of a degree (or 1/60
of an arc minute). Asterism: A small unofficial grouping of stars in the night
sky.
Asteroid: A small, rocky body that orbits a star.
Astrology: The pseudoscientific belief that the positions of stars and
planets exert an influence on human affairs; astrology has nothing in common
with astronomy.
Astronomical unit (AU): The distance between the Earth and the Sun. It is
equal to 149,597,900 km., usually rounded off to 150,000,000 km.
Aurora: The emission of light when charged particles from the solar wind
slam into and excite atoms and molecules in a planet’s upper atmosphere.
Azimuth: The angular distance of an object eastwards along the horizon,
measured from due north, between the astronomical meridian (the vertical line
passing through the center of the sky and the north and south points on the
horizon) and the vertical line containing the celestial body whose position is
to be measured.
B Binary Stars: Binary (Double) stars are pairs of stars that, because of
their mutual gravitational attraction, orbit around a common center of mass.
If a group of three or more stars revolves around one another, it is called
multiple systems. It is believed that approximately 50 percent of all stars
belong to binary or multiple systems. Systems with individual components that
can be seen separately by a telescope are called visual binaries or visual
multiples. The nearest “star” to our solar system, Alpha Centauri, is actually
our nearest example of a multiple star system, it consists of three stars, two
very similar to our Sun and one dim, small, red star orbiting around one
another.
C
Celestial Equator: The projection of the Earth’s equator onto the
celestial sphere. It divides the sky into two equal hemispheres. Celestial
pole: The imaginary projection of Earth’s rotational axis north or south
pole onto the celestial sphere. Celestial Sphere: An imaginary sphere
surrounding the Earth, concentric with the Earth’s center.
Collimation: The act of putting a telescope’s optics into perfect
alignment.
D
Declination (DEC): The angular distance of a celestial body north or
south of the celestial equator. It may be said to correspond to latitude on
the surface of the Earth.
E
Ecliptic: The projection of the Earth’s orbit onto the celestial sphere.
It may also be defined as “the apparent yearly path of the Sun against the
stars”.
Equatorial mount: A telescope mounting in which the instrument is set
upon an axis that is parallel to the axis of the Earth; the angle of the axis
must be equal to the observer’s latitude.
F
Focal length: The distance between a lens (or mirror) and the point at
which the image 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 planets that are at a greater
distance from the sun than the terrestrial planets.
K
Kuiper Belt: A region beyond the orbit of Neptune extending to about 1000
AU which is a source of many short-period comets. L
Light-Year (ly): A light-year is the distance light traverses in a vacuum
in one year at the speed of 299,792 km/ sec. With 31,557,600 seconds in a
year, the light-year equals a distance of 9.46 X 1 trillion km (5.87 X 1
trillion mi).
M
Magnitude: Magnitude is a measure of the brightness of a celestial body.
The brightest stars are assigned magnitude 1 and those increasingly fainter
from 2 down to magnitude 5. The faintest star that can be seen without a
telescope is about magnitude 6. Each magnitude step corresponds to a ratio of
2.5 in brightness. Thus a star of magnitude 1 is 2.5 times brighter than a
star of magnitude 2, and 100 times brighter than a magnitude 5 star. The
brightest star, Sirius, has an apparent magnitude of -1.6, the full moon is
-12.7, and the Sun’s brightness, expressed on a magnitude scale, is -26.78.
The zero point of the apparent magnitude scale is arbitrary.
Meridian: A reference line in the sky that starts at the North celestial
pole and ends at the South celestial pole and passes through the zenith. If
you are facing South, the meridian starts from your Southern horizon and
passes directly overhead to the North celestial pole.
Messier: A French astronomer in the late 1700s who was primarily looking
for comets. Comets are hazy diffuse objects and so Messier cataloged objects
that were not comets to help his search. This catalog became the Messier
Catalog, M1 through M110.
N
Nebula: Interstellar cloud of gas and dust. Also refers to any celestial
object that has a cloudy appearance. North Celestial Pole: The point in the
Northern hemisphere around which all the stars appear to rotate. This is
caused by the fact that the Earth is rotating on an axis that passes through
the North and South celestial poles. The star Polaris lies less than a degree
from this point and is therefore referred to as the “Pole Star”.
Nova: Although Latin for “new” it denotes a star that suddenly becomes
explosively bright at the end of its life cycle.
O
Open Cluster: One of the groupings of stars that are concentrated along
the plane of the Milky Way. Most have an asymmetrical appearance and are
loosely assembled. They contain from a dozen to many hundreds of stars.
P
Parallax: Parallax is the difference in the apparent position of an
object against a background when viewed by an observer from two different
locations. These positions and the actual position of the object form a
triangle from which the apex angle (the parallax) and the distance of the
object can be determined if the length of the baseline between the observing
positions is known and the angular direction of the object from each position
at the ends of the baseline has been measured. The traditional method in
astronomy of determining the distance to a celestial object is to measure its
parallax.
Parfocal: Refers to a group of eyepieces that all require the same
distance from the focal plane of the telescope to be in focus. This means when
you focus one parfocal eyepiece all the other parfocal eyepieces, in a
particular line of eyepieces, will be in focus.
Parsec: The distance at which a star would show parallax of one second of
arc. It is equal to 3.26 light-years, 206,265 astronomical units, or
30,8000,000,000,000 km. (Apart from the Sun, no star lies within one parsec of
us.)
Point Source: An object which cannot be resolved into an image because it
to too far away or too small is considered a point source. A planet is far
away but it can be resolved as a disk. Most stars cannot be resolved as disks,
they are too far away.
R
Reflector: A telescope in which the light is collected by means of a
mirror.
Resolution: The minimum detectable angle and the optical system can
detect. Because of diffraction, there is a limit to the minimum angle,
resolution. The larger the aperture, the better the resolution.
Right Ascension (RA): The angular distance of a celestial object measured
in hours, minutes, and seconds along the Celestial Equator eastward from the
Vernal Equinox.
S
Sidereal Rate: This is the angular speed at which the Earth is rotating.
Telescope tracking motors drive the telescope at this rate. The rate is 15 arc
seconds per second or 15 degrees per hour.
T
Terminator: The boundary line between the light and dark portion of the
moon or a planet. U Universe: The totality of astronomical things, events,
relations, and energies capable of being described objectively.
V
Variable Star: A star whose brightness varies over time due to either
inherent properties of the star or something eclipsing or obscuring the
brightness of the star.
W
Waning Moon: The period of the moon’s cycle between full and new, when
its illuminated portion is decreasing. Waxing Moon: The period of the moon’s
cycle between new and full, when its illuminated portion is increasing.
Z
Zenith: The point on the Celestial Sphere directly above the observer.
Zodiac: The zodiac is the portion of the Celestial Sphere that lies
within 8 degrees on either side of the Ecliptic. The apparent paths of the
Sun, the Moon, and the planets, with the exception of some portions of the
path of Pluto, lie within this band. Twelve divisions, or signs, every 30
degrees in width, comprise the zodiac. These signs coincided with the zodiacal
constellations about 2,000 years ago. Because of the Precession of the Earth’s
axis, the Vernal Equinox has moved westward by about 30 degrees since that
time; the signs have moved with it and thus no longer coincide with the
constellations.
Time Zones
Sky Maps
January – February Sky
March – April Sky
May – June Sky
July – August Sky
September – October Sky
November – December Sky
One-Year Limited Warranty
This Orion product is warranted against defects in materials or workmanship
for a period of one year from the date of purchase. This warranty is for the
benefit of the original retail purchaser only. During this warranty period
Orion Telescopes & Binoculars will repair or replace, at Orion’s option, any
warranted instrument that proves to be defective, provided it is returned
postage paid. Proof of purchase (such as a copy of the original receipt) is
required. This warranty is only valid in the country of purchase. This
warranty does not apply if, in Orion’s judgment, the instrument has been
abused, mishandled, or modified, nor does it apply to normal wear and tear.
This warranty gives you specific legal rights. It is not intended to remove or
restrict your other legal rights under applicable local consumer law; your
state or national statutory consumer rights governing the sale of consumer
goods remain fully applicable. For further warranty information, please visit
www.OrionTelescopes.com/warranty.
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