Celestron StarSense Explorer DOB User manual

INSTRUCTION MANUAL
#22470 STARSENSE EXPLORER 8” DOBSONIAN
#22471 STARSENSE EXPLORER 10” DOBSONIAN
#22472 STARSENSE EXPLORER 12” DOBSONIAN

2I ENGLISH
TABLE OF CONTENTS
What’s in the Box . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3
Base Assembly . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5
Telescope Assembly . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6
Pointing the Telescope . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .7
Focusing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .8
Using the StarPointer . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9
StarSense Explorer Dock and App . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10
Determining Magnification and Selecting Eyepieces . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11
Cooling your Telescope’s Optics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11
Your First Night Out - What to Expect . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12
Dark Adaptation and Light Pollution . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13
Use of Filters . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13
Note about Smartphone Power . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .13
Collimating the Optics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14
Transporting . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16
Care and Maintenance . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .17
Specifications StarSense Explorer 8” Dobsonian . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18
Specifications StarSense Explorer 10” Dobsonian. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .19
Specifications StarSense Explorer 12” Dobsonian . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20
Solar Warning . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21
INTRODUCTION
Congratulations on your purchase of the StarSense Explorer Dobsonian (SSE Dob) telescope. Your SSE Dob combines large
optics with the exciting StarSense Explorer dock and app to make finding and observing all kinds of astronomical objects fun
and easy! You’ll be able to locate faint deep-sky objects—galaxies, nebulae, star clusters and more— and place them within the
field of view of the eyepiece in seconds. The large primary mirror collects lots of light, enabling you to see details in objects that
you have never seen before.
Before you take your StarSense Explorer Dob outside for your first night of observing, we recommend reading through this
manual. It will help you to better understand the features of your telescope and know what to expect.

ENGLISH I 3
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WHAT’S IN THE BOX
Box 1 - Dobsonian Base
Box 2 - Optical Tube Assembly
Left side panel
Feet (x3)
AZIMUTH PIVOT BOLT ASSEMBLYFEET ASSEMBLY
HANDLE ASSEMBLY EYEPIECE RACK ASSEMBLY
INCLUDED TOOLS
ALTITUDE BEARING ASSEMBLY
Base
handle
Eyepiece rack
Rubber
bumper
Optical tube assembly with dust cover
25mm Omni
Plössl eyepiece
(8” and 10” Dobs)
32mm Omni
Plössl eyepiece
(12” Dob only)
2”-to1.25” eyepiece
adapter with 1.25”
cover cap
2” focuser
extension tube
Collimation cap with
2mm and 2.5mm hex keys*
*2.5mm hex key included with 8” Dob only
NOTE: For collimating your telescope’s
optics, refer to page 14
Altitude
tensioning knob
Cosmetic knob
Screwdriver
StarSense dock StarPointer
red dot finderscope
Crescent
wrenches (x2)
Hex keys (x2)
Rack
Screws (x2)
Altitude bearing
cylinders (x4)
Bearing
screws (x4)
Handle
screws (x2)
Feet screw
covers (x3)
Feet screws
(x3)
Bolt Nut Steel
washers
(x2)
Hollow
plastic
cylinder
Teflon
washer
Right side panel Front panel Top plate Bottom plate
Side supports
(x2)
Base assembly screws
(x22 for 8” & 10” Dobs)
(x27 for 12” Dob)

4I ENGLISH
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Box 3 - Primary Mirror (12” Dob only)
Primary mirror in mirror cell
BACKFRONT
Mirror cell screws (x6)

ENGLISH I 5
Mirror cell screws (x6)
BASE ASSEMBLY
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Figure 1A: Exploded view of the StarSense
Explorer Dobsonian base.

6I ENGLISH
Figure 1B: Exploded view of the StarSense Explorer Optical Tube Assembly
Refer to Figure 1 to see how the parts of the SSE Dob fit together.
For detailed assembly instructions, refer to the printed Quick Setup Guide included in the box, or on the SSE Dob product page
at www.celestron.com
TELESCOPE ASSEMBLY
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ENGLISH I 7
POINTING THE TELESCOPE
Dobsonian bases are altazimuth mounts. This means that
the telescope moves in two directions: up-and-down
(i.e. altitude), and left-to-right (i.e. azimuth) (Figure 2).
ALTITUDE
AZIMUTH
Figure 2: The StarSense Explorer Dobsonians have two axes of motion:
altitude (up-and-down) and azimuth (left-to-right).
Pointing your Dob at an object is easy. Simply move the
telescope tube up-and-down and left-to-right until the
telescope is pointed toward the desired object and the
object appears in the telescope’s eyepiece. The panning
knob at the front of the telescope tube provides a convenient
place to grasp the tube for pointing (Figure 3). Using this
knob also prevents heat from your hand from entering the
optical path, which can temporarily distort the view.
Figure 3: The panning knob provides an excellent place for your fingers to
grasp when pointing the telescope.
You can adjust the tension along the altitude axis by turning
the knob located on the same side as the telescope’s
focuser—the altitude tensioning knob (Figure 4).
Figure 4: The tension of the altitude motion can be adjusted with the
altitude tensioning knob. (NOTE: the other knob on the opposite side does
not function for adjusting altitude tension.)
Turn the knob to add enough tension to provide a smooth
up-and-down motion. Under most circumstances you won’t
need to add much tension. The telescope is balanced for
normal use. However, if you are using a heavy eyepiece or
a larger smartphone, you may need to add more tension so
that the telescope remains still when not touched.

8I ENGLISH
FOCUSING
The SSE Dobs come with a 2” Crayford focuser, a 2”
extension tube, and a 2”-to-1.25” eyepiece adapter.
With these three items, you can use virtually any telescope
eyepiece with the SSE Dob.
For most eyepieces, make sure the 2” extension tube
is in place in the focuser. If it’s not, the eyepiece will not
reach focus. If you’re using an eyepiece that requires a lot of
inward focus travel, remove the 2” extension tube. You may
need to remove the tube if attempting to use your Dob with
an astronomical imaging camera.
If you wish to use a 1.25” format eyepiece, you’ll need to
use the 2”-to-1.25” eyepiece adapter. Simply place it in the
focuser (with 2” extension tube attached), and then place
the 1.25” eyepiece in the adapter. Tighten the thumbscrew
on the adapter to secure the eyepiece in place. The adapter
uses an internal brass compression ring so your eyepiece
barrel won’t be scratched or marred.
To focus, turn the focus knobs clockwise or counterclockwise
until the object in the telescope eyepiece is in sharp focus.
To lock the focuser position in place once you have achieved
sharp focus, tighten the focus lock thumbscrew (Figure
5). If you need to adjust the focus knob’s tension, you can
tighten or loosen the focuser tensioning set screw using the
provided hex key.
FOCUS LOCK
THUMBSCREW
FOCUSER
TENSIONING
SET SCREW
Figure 5: The focus lock thumbscrew locks the focuser in place once
focus has been achieved. The focus tensioning set screw adjusts the
tension of the focusing knobs.
Since the SSE Dob is a Newtonian reflector, the images
you’ll see will appear upside-down as compared to the
naked eye (Figure 6). While this has little impact on
astronomical observing, it can be a bit confusing when you
are viewing land-based objects.
Figure 6: Like all Newtonian reflectors, the SSE Dobs produce images
that appear upside-down as compared to the naked eye.
VIEW THROUGH NEWTONIAN REFLECTOR TELESCOPE
NAKED EYE VIEW

ENGLISH I 9
USING THE STARPOINTER
Although you won’t need to rely on the StarPointer red-dot
finder when you are using the StarSense Explorer app, it can
help you align the app with the telescope. The StarPointer
also comes in handy when you are locating objects during
the day, since the app only works under the stars at night.
To align the StarPointer, first point the telescope at an
object that is at least ¼ mile away. We recommend aligning
during the day. Choose a distant tree, sign, building, or
other landmark. If you are aligning at night, you can use a
streetlight, the Moon, or a bright star or planet.
Once you have pointed the telescope at the object, check
to ensure that it appears in the eyepiece. Next, turn the
StarPointer on using the LED dial (Figure 7).
LED DIAL
ALTITUDE KNOB AZIMUTH KNOB
Figure 7: The StarPointer red-dot finderscope.
Turn up the brightness level until you can easily see the
red dot. Now, without moving the telescope, use the
StarPointer’s altitude and azimuth adjustment knobs to
center the red dot on the same object that you centered
in the telescope eyepiece. When you’re finished, check
to make sure the object is still centered in the telescope
eyepiece. If it is, you are done aligning the StarPointer. If
not, move the telescope so the object in the telescope’s
eyepiece is centered again. Continue using StarPointer’s
altitude and azimuth adjustment knobs to center the red dot
on the object again.
Turn off the StarPointer when you aren’t using it to conserve
its battery. While the StarPonter’s battery should last a long
time, eventually it will need to be replaced with a CR2032
3V Lithium button cell battery. These are very common and
available from a wide variety of retailers.
To replace the battery:
1. Use a Phillips-head screwdriver to remove the battery
cover securing screw (Figure 8).
Figure 8: To open the StarPointer’s battery cover, first remove the
securing screw.
2. Remove the discharged battery from the battery com-
partment. You may need to use a knife or screwdriver to
pry the battery out of its holder.
3. Insert the new battery so that the positive side is visible to
you. Make sure the battery is properly seated within the
battery compartment (Figure 9).
Figure 9: When the battery is properly seated in the compartment as
shown, the battery cover should be easy to reinstall.
4. Close the battery compartment and reinstall the securing
screw.

10 I ENGLISH
STARSENSE EXPLORER DOCK
AND APP
Perhaps the most exciting feature of the StarSense
Explorer Dobsonian is the StarSense Explorer dock and the
StarSense Explorer smartphone app. With the app to guide
you, you’ll spend more time observing objects instead of
struggling to find them among myriad stars overhead! The
Celestron StarSense Explorer is the only Dobsonian that
includes this incredible feature.
To begin, download and install the app from the Apple
App Store (iOS) or Google Play (Android). You’ll also find
the minimum system requirements there. If you have any
questions about whether your smartphone is compatible
with the app, please visit celestron.com/SSE
Once you have downloaded the app, use the app unlock
code that you’ll find on the printed card that came with your
telescope (Figure 10).
Download the app from the
before your first observing session
.
or
When prompted, enter the unique unlock code below to
enable telescope control on your device.
Figure 10: The StarSense Explorer App unlock code is printed on the card
included with your telescope.
Each code can enable up to five devices to use the
StarSense Explorer functionality. If you use the code all five
times and need to unlock the app on more devices, please
contact Celestron Technical Support at celestron.com/
pages/technical-support for options.
With the app unlocked, you are ready to begin. Place your
smartphone into the StarSense Explorer dock and press
the StarSense icon at the bottom of the planetarium screen
(Figure 11).
Choose the “NEEDS ALIGNMENT” option and follow the
on-screen prompts to align the smartphone’s camera with
the telescope. Once this procedure is complete, you can
use the app to locate objects.
Select an object to view from the planetarium or the
“Tonight’s Best” list (i.e. press the star icon). Arrows will
appear on screen, guiding you to the object. Follow the
arrows until the bullseye turns green and the object is in
your telescope’s field of view. It’s that easy!
While you observe, you can read detailed information about
the object. Hundreds of the most popular objects also offer
an audio presentation. To listen, press the bar at the bottom
of the screen that contains the object’s name (Figure 12).
STARSENSE ICON
Figure 11: Once you have unlocked the StarSense Explorer app, press the
StarSense icon to begin finding objects.
Figure 12: Press the Object Info bar to receive additional information about
the selected object, including images and audio presentations for many
objects.

ENGLISH I 11
DETERMINING MAGNIFICATION
AND SELECTING EYEPIECES
To change the magnification of the telescope, you’ll need
to change the eyepiece in the telescope’s focuser. To
calculate the magnification you can achieve with a given
eyepiece, use this formula:
Focal length of telescope ÷
Focal length of eyepiece
= Magnification
The 8” and 10” SSE Dobs have a focal length of 1200mm
and come with a 25mm Omni Plössl eyepiece. Using
the formula, we can calculate that this combination
yields a magnification of 48x (1200mm ÷ 25mm =
48x). The 12” SSE Dob has a focal length of 1500mm
and comes with a 32mm Omni Plössl eyepiece – this
provides a magnification of 47x (1500mm ÷ 32mm =
47x). This is an excellent magnification for locating and
observing wide-field deep space objects. You may want
to consider purchasing a higher-magnification eyepiece,
like a 10mm Omni Plössl, for higher-power views of the
Moon and planets. Do not increase magnification too much
though, or the view may degrade due to atmospheric seeing
conditions (i.e. air turbulence).
The maximum magnification for any telescope is about
60 times per inch, which equates to 480x for the 8” SSE
Dob, 600x for the 10” SSE Dob , and 720x for the 12”
SSE Dob. In many locations, however, it will be difficult to
achieve sharp images much over 100x magnification due to
turbulence in the air above you. If you notice that the stars
overhead are twinkling heavily, seeing conditions are poor.
You should stick to lower magnification. If the stars appear
to shine steadily, seeing conditions are good. You can try
using higher-magnification eyepieces.
The SSE Dobs can accept both 1.25” and 2” format
eyepieces. 2” eyepieces generally provide a wider field of
view but can cost significantly more. To use a 2” eyepiece,
remove the 2”-to-1.25” adapter from the focuser and insert
the eyepiece directly into the 2” extension tube. Secure the
eyepiece with the thumbscrews on the 2” extension tube.
The eyepiece rack located on the front of the base provides
a convenient place to put eyepieces when they are not
in use. It can accept three 1.25” eyepieces and one 2”
eyepiece (Figure 13).
Figure 13: The eyepiece rack is a convenient place to store additional
eyepieces during your observing session.
COOLING YOUR
TELESCOPE’S OPTICS
You’ll get the best views through your telescope when it
has reached thermal equilibrium with the ambient air. If
the telescope is warmer than the outside air, the mirror
will acclimate to the temperature and its figure will be
changing. The images you see through a telescope that
has not cooled will not appear as sharp as they otherwise
would. If you are taking your telescope from a heated house
to the outdoors, allow around one hour before expecting it
to produce sharp images. For this reason, we recommend
storing your telescope in a dry but unheated area like a
garage or storage shed. We also recommend taking the
telescope out at sunset, so it will already be acclimated
by the time it gets dark.
For the 10” and 12” SSE Dobs, there is an optional USB
Cooling Fan for Dobsonians available. It mounts onto the rear
of the mirror cell and blows air on the mirror to expedite cool-
ing (Figure 14). The fan will help the optics reach thermal
equilibrium faster. (The 8” SSE Dob does not have a fan
mount so it is not compatible with the Cooling Fan.)
Figure 14: The optional USB Cooling Fan for Dobsonians is compatible with
the 10” and 12” SSE Dobs.

12 I ENGLISH
YOUR FIRST NIGHT OUT 
WHAT TO EXPECT
You can observe literally thousands of objects with the
larger aperture of the SSE Dobs:
The Moon
Observing the lunar surface is a great place to start. You’ll
easily see craters, maria, lacus, valleys, mountains, and
other features. The Moon is so bright that you might want
to consider using an optional Moon filter. It threads onto
bottomoftheeyepiecetodimtheview.Wealsorecommend
a higher-power eyepiece to help you explore the Moon
up-close.
Planets
The best planets to view are Jupiter, Saturn, Mars, and
Venus. A higher-power eyepiece will help bring out the
fine details. You’ll be able to see the rings of Saturn,
surface detail on Jupiter along with its moons, the phases
of Venus, and perhaps some surface detail on Mars if it is
near opposition (i.e. when it is closest to the Earth).
Stars and Double Stars
Stars will appear like points of light regardless of the
magnification used. However, a telescope can reveal a
star’s color and also “split” double stars using higher
magnifications. For variable stars, see if you can detect
a star’s change in brightness over a period of days or
weeks.
Open Star Clusters
These are star groups that formed together within our
Milky Way galaxy. They can appear spectacular in the
telescope eyepiece, even from somewhat light-polluted
skies. Astronomers often describe star clusters as
resembling “crushed diamonds on black velvet” in the
telescope’s eyepiece. Clusters are generally best viewed
with low-power eyepieces, as they usually require a wide
field of view to see the entire cluster.
Globular Star Clusters
These are tight clusters of hundreds of thousands of
stars that coalesced early in our galaxy’s formation. These
clusters appear like globes of light. The brighter ones can
be resolved into individual stars in good conditions. Most
globular clusters are best viewed with a medium-power
eyepiece, as they are not nearly as wide as open clusters,
yet not bright enough for high power either.
Nebulae
You’ll generally need to be under dark skies to see
gaseous nebulae, which appear as a faint glow around
stars. Don’t expect to see any nebulosity from urban skies
except for perhaps the brightest ones, like the Orion
Nebula and Lagoon Nebula.
Galaxies
Perhaps the most fascinating of all objects to view,
galaxies are like “island universes” unto themselves.
While you can detect the brightest galaxies, like the
Andromeda Galaxy, from somewhat light-polluted skies,
they are best observed from dark skies. Literally hundreds
of galaxies are well within the observing reach of the SSE
Dobs. The best ones display fine details like faint spiral
arms and dust lanes. Many, however, will just appear as
non-stellar “streaks” or “blobs.” Even so, just being able
to detect the light from another galaxy outside our own is
rewarding in itself.
One thing to keep in mind is that the SSE Dobs are not
motorized. This means that they will not automatically track
celestial objects as the Earth rotates. As a result, you will
notice that objects drift a bit as you observe them and will
exit the eyepiece’s field of view within a minute or two,
depending on the magnification you are using. Objects will
drift out of the field of higher-power eyepieces faster, since
their field of view is narrower. You will need to manually push
the Dob along to keep objects centered over time. This is
easy to do. Grab hold of the telescope’s panning knob and
move it slightly up-and-down and left-to-right as needed.

ENGLISH I 13
DARK ADAPTATION AND
LIGHT POLLUTION
It takes at least a half-hour for the human eye to become
dark-adapted, so don’t immediately expect to see subtle
detail in faint deep-sky objects as soon as you get outside.
While you are observing, avoid any bright lights (like
going from outside to inside a lighted house) or else your
dark adaption will need time to reset. Use red flashlights
designed for astronomical use, as the red light will not
greatly affect your night vision. The Moon will also affect
your dark adaptation, so if you directly observe the Moon
expect it to take time to regain your night vision.
Local light pollution will greatly diminish the appearance
and contrast of fainter deep-sky objects in the telescope.
Do not expect to see much detail from urban skies. You’ll
get your best views from dark sky locations away from city
or suburban night lighting. Bright objects such as the Moon,
planets, double stars, and bright open star clusters are not
affected by light pollution as much, so they make good
objects for backyard viewing regardless of where you are.
Also keep in mind that the Moon itself can light up much of
the night sky, preventing views of faint objects even from
dark sites. So schedule deep sky observing when the Moon
won’t be visible.
USE OF FILTERS
Experiment with adding optional filters to your setup to
help improve the view. Astronomical filters thread onto the
bottom of your eyepiece and usually come in both 1.25” and
2” formats. Simply remove the eyepiece from the focuser,
thread the filter onto the bottom of the eyepiece’s barrel,
and then reinsert it into the focuser.
There are many useful filters to choose from:
Moon Filter – An essential for viewing lunar details, this
filter cuts down on glare and makes bright objects dimmer.
Variable Polarizer – Like a Moon filter, a polarizer dims your
view. The key difference is that you can customize the extent
of the dimming effect by rotating the polarizer.
Color Filters – Available in a variety of colors, these can
improve contrast when observing planetary details.
Light Pollution Filters – If you are viewing deep-space
objects from urban or suburban skies, these improve
contrast by blocking the “bad” light from local light pollution
and transmitting the “good light” from deep-sky objects.
You’ll notice the greatest improvement in contrast when
observing nebulae
NOTE ABOUT
SMARTPHONE POWER
Before going out for a night of observing with your
StarSenese Explorer Dobsonian, be sure your smartphone
is well-charged. While running the StarSense Explorer app,
the smartphone’s camera is constantly looking at the sky
and its processor is continuously determining the current
sky location, so it uses significant power. If your smartphone
is fully-charged it should last several hours but if you plan to
observe all night, we recommend bringing along a charger
for your smartphone.
Celestron offers a very handy portable charger called the
PowerTank Glow 5000, which also has a built-in red LED
flashlight. The SSE Dobs have a specific mounting location
for the PowerTank Glow 5000 that utilizes the connecting
bands which come with the PowerTank (Figure 14a).
Simply mount the PowerTank onto the posts on the base
of the StarSense dock, then connect the PowerTank to
your smartphone with your charging cable while it is in the
StarSense dock. This will provide plenty of power to your
smartphone for longer observing sessions.
Figure 14a: The PowerTank Glow 5000 mounts onto the posts on the base
of the StarSense dock using the bands included with the PowerTank.

14 I ENGLISH
COLLIMATING THE OPTICS
Collimation is the process of aligning the telescope’s optics.
Dobsonians use the Newtonian reflector optical design,
which consists of a parabolic primary mirror and a flat
secondary mirror. To ensure best performance, you should
periodically check the alignment of the optics. To help with
this, we have included a special “collimation cap” you can
use. In addition, the primary mirror is center-marked with an
adhesive ring label to aid in collimation.
To check alignment of the mirrors, first remove any
eyepieces. Make sure the 2”-to-1.25” adapter is installed in
the focuser. Then, place the collimation cap in the focuser
(Figure 15).
Figure 15: To check the alignment of the mirrors, use the included
collimation cap in the focuser.
Look through the small hole in the center of the collimation
cap. The view should look like Figure 16. If it does not, you’ll
need to make some adjustments to the mirrors’ alignment.
Bottom edge
of focuser
drawtube
Reflection of
your eye
Edge of
secondary
mirror
Secondary
mirror
holder
Primary
mirror clip
Reflection of
secondary mirror holder
Figure 16: If your telescope is properly aligned, the view through the
collimation cap should look like the drawing above.
It is easiest to collimate a telescope during the day with
the telescope pointed toward a blank wall. This will provide
a high-contrast view, making it easier to determine which
adjustments should be made. Use the supplied hex key(s)
to make adjustments. The 8” SSE Dob comes with 2mm
and 2.5mm hex keys. The 10” and 12” SSE Dobs come with
a single 2mm hex key. For the 8” SSE Dob, you’ll also need
to use the supplied Phillips head screwdriver.
First, adjust the secondary mirror at the front of the telescope
using the 2mm hex key. While making adjustments, we
recommend positioning the tube horizontally. This prevents
anything from falling onto the primary mirror.
1. You should be able to see the reflection of the entire
primary mirror centered within the secondary mirror as
shown in Figure 16. If you can’t (like in Figure 17, for
example), use the three socket-head set screws in the
secondary mirror holder to adjust the tilt of the secondary
mirror (Figure 18).
Edge of
secondary
mirror
Reflection of
primary mirror
Figure 17: If the reflection of the primary mirror is not centered within
the secondary mirror as shown above, you will need to adjust the tilt of
the secondary mirror.
2mm
Hex key
Figure 18: The three socket head set screws in the secondary mirror
holder adjust the tilt of the secondary mirror.
Reflection
of primary
mirror

ENGLISH I 15
a. Adjust one set screw at a time. Make only small
adjustments.
b. If one set screw becomes too tight or too loose, make
adjustments to the other set screws to compensate.
2. Continue adjusting the set screws until the primary mirror
appears centered within the secondary mirror (Figure
19). When you are finished, make sure all three of the set
screws are snug.
Edge of
secondary
mirror
Reflection of
primary mirror
Reflection of
secondary mirror
Figure 19: Continue making tilt adjustments to the secondary mirror until
the primary mirror reflection is centered as shown in the drawing above.
3. Next, adjust the tilt of the primary mirror until the reflection
of the secondary mirror is centered within the reflection
of the primary mirror.
For the 8” Dobsonian, use the 2.5mm hex key and
Phillips head screwdriver to tilt the primary mirror. There are
three pairs of collimation screws. Each pair works together
to adjust the tilt.
a. Adjust one pair of screws at a time. Start by
loosening one of the screws in the pair and
tightening the other (Figure 20).
Figure 20: For the 8” Dob, there are three sets of push-pull screws
in the mirror cell that adjust the tilt of the primary mirror. Loosen one
screw in the pair and tighten the other to adjust the tilt.
b. If the mirror tilts opposite the desired direction,
loosen the screw that you previously tightened,
and tighten the other screw in the pair.
c. Once you have adjusted one pair of screws as
much as you can, move onto another pair of screws.
d. Continue adjusting until the reflection of the
secondary mirror is centered within the reflection
of the primary mirror. When you are finished, the
view through the collimation cap should look like
Figure 16.

16 I ENGLISH
For the 10” and 12” Dobsonians, you won’t need
any tools to tilt the primary mirror. Instead, simply adjust
the thumbscrews. Three of the thumbscrews are locking
screws, while the other three thumbscrews adjust the
tilt.
a. Start by loosening all three of the locking
thumbscrews (Figure 21).
10 INCH DOB
LOCKING
THUMBSCREWS
12 INCH DOB
LOCKING
THUMBSCREWS
Figure 21: For the 10” and 12” Dobs, there are three spring-loaded
collimation thumbscrews that adjust the tilt of the primary mirror. The
other three thumbscrews lock the mirror in place once tilt adjustments
are completed.
b. Adjust the collimation thumbscrews one at a time.
Each collimation thumbscrew is spring-loaded, so
you can rotate it clockwise or counterclockwise.
c. Continue adjusting the screws until the reflection
of the secondary mirror is centered within the
reflection of the primary mirror.
d. Re-tighten the three locking thumbscrews until
snug.
e. When you are finished, the view through the
collimation cap should look like Figure 16.
Your telescope’s optics are now aligned and ready for use.
You can also confirm a telescope’s alignment at night by
pointing the telescope at a bright star at high magnification.
Center the star in the field of view and slightly defocus the
star—it should appear like a circle with a hole in the middle.
(The “hole” is the shadow from the secondary mirror.) If the
hole is not centered within the circle, you’ll need to make
additional adjustments to collimation (Figure 22).
GOOD COLLIMATION NEEDS ADJUSTMENT
Figure 22: You can check collimation by defocusing a bright star centered
in the field of view and checking to see if the “hole” is centered. If it is not
centered, some adjustment is needed.
TRANSPORTING
Transporting the StarSense Explorer Dobsonian is
easy, especially considering its size. First, remove the
telescope tube from the base by loosening the altitude
tensioning knob and lifting the telescope tube. You can
carry the tube and the base separately by their integrated
carry handles. The handles are positioned to balance the
load, so neither component should be awkward to carry.
The 12” Dob optical tube weighs nearly 50 lbs. so make
sure to bend your knees when lifting and do not overexert
yourself! If it is too heavy for you to carry alone, we
recommend having another person assist.

ENGLISH I 17
CARE AND MAINTENANCE
Store the telescope indoors in a dry place. A garage is
ideal; it will keep the optics near the ambient outdoor
temperature so the optics won’t take as long to acclimate.
Keep the dust cover on the front of the telescope and the
cover cap on the focuser when the telescope is not in
use. Otherwise, dust and particles can accumulate on
the optics.
If the telescope is wet from dew, dry the exterior of the
telescope tube and base with a towel prior to storage.
While a small amount of water on the exterior of the
tube and base won’t harm the telescope, storing it wet
long-term could cause corrosion or water damage. The
wooden base has sealed melamine surfaces. Still, water
can seep into cracks if left wet during storage.
It is normal for some dust and particles to accumulate on
the primary mirror over time. They will not have any effect
on optical performance. However, if the primary mirror
gets excessively dirty, you should clean it.
To clean the primary mirror:
1. Remove the primary mirror cell from the telescope
tube by removing the screws on the tube just above
the mirror cell (Figure 23). You’ll need the Phillips
head screwdriver to do this.
2. Carefully pull the mirror cell off of the tube.
3. The mirror surface is now exposed for cleaning.
We recommend leaving the primary mirror in its cell
during cleaning.
4. Use a blower bulb and optics cleaning brush to
remove larger particles and dust. In some instances,
this will be all the cleaning necessary.
Figure 23: To remove the primary mirror from the telescope tube for
cleaning, first remove the screws located just above the mirror cell.
5. To remove marks and oils, use lens cleaning fluid
and lens cleaning tissue to clean the mirror surface.
Apply the fluid to the tissue and gently wipe the
mirror surface. Use radial strokes (i.e. from the
center of the mirror to the edge). Use a new tissue
for every wipe. Avoid rubbing; this typically just
spreads oils around instead of removing them.
6. Once the mirror is clean, reinstall the mirror cell
into the telescope tube and replace the screws.
The secondary mirror will not get dirty often, as its optical
surface is pointed downward. However, if it does require
cleaning, it can be cleaned in the same manner as the
primary mirror. You do not need to remove the secondary
mirror from the telescope to clean it. Point the telescope
horizontally during cleaning to prevent anything from
falling onto the primary mirror.
You may clean the exposed optical surfaces of your
eyepieces in the same manner described above.

18 I ENGLISH
#22470 StarSense Explorer 8” Dobsonian
Optical Design Newtonian reflector
Aperture 8” (203mm)
Focal Length 1200mm
Focal Ratio F/5.9
Optical Coatings XLT reflective coatings with silicon dioxide and tantalum pentoxide protective
overcoatings for primary and secondary mirrors
Mirror Material Pyrex equivalent for primary and secondary mirrors
Primary mirror thickness 25mm (approx. 1:8 thickness ratio)
Secondary mirror thickness 8.5mm
Minor axis of secondary mirror 47mm
Tube material Steel
Focuser 2” Crayford, includes 2” extension tube and 2”-to-1.25” adapter
Eyepiece / Magnification 25mm Plössl, 48x
Finderscope StarPointer red-dot finderscope
Other Accessories StarSense Explorer dock, eyepiece rack, collimation cap,
carry handles for OTA and base, pointing knob, dust covers
Tripod Altazimuth Dobsonian base, adjustable altitude tensioning
Optical Tube Dimensions 44” x 9.5” diameter
Optical Tube Weight 20.6 lbs.
Base dimensions 27” x 19” x 19”
Base weight 22.8 lbs.
Total Telescope Kit Weight 43.4 lbs.
SPECIFICATIONS

ENGLISH I 19
#22471 StarSense Explorer 10” Dobsonian
Optical Design Newtonian reflector
Aperture 10” (254mm)
Focal Length 1200mm
Focal Ratio F/4.7
Optical Coatings XLT reflective coatings with silicon dioxide and tantalum pentoxide protective
overcoatings for primary and secondary mirrors
Mirror Material Pyrex equivalent for primary and secondary mirrors
Primary mirror thickness 30mm (approx. 1:8.5 thickness ratio)
Secondary mirror thickness 11.5mm
Minor axis of secondary mirror 64mm
Tube material Steel
Focuser 2” Crayford, includes 2” extension tube and 2”-to-1.25” adapter
Eyepiece / Magnification 25mm Plössl, 48x
Finderscope StarPointer red-dot finderscope
Other Accessories StarSense Explorer dock, eyepiece rack, collimation cap,
carry handles for OTA and base, pointing knob, dust covers
Tripod Altazimuth Dobsonian base, adjustable altitude tensioning
Optical Tube Dimensions 44” x 11.5” diameter
Optical Tube Weight 29.2 lbs.
Base dimensions 26.5” x 21” x 21”
Base weight 25.6 lbs.
Total Telescope Kit Weight 54.8 lbs.
SPECIFICATIONS

20 I ENGLISH
#22472 StarSense Explorer 12” Dobsonian
Optical Design Newtonian reflector
Aperture 12” (305mm)
Focal Length 1500mm
Focal Ratio F/4.9
Optical Coatings XLT reflective coatings with silicon dioxide and tantalum pentoxide protective
overcoatings for primary and secondary mirrors
Mirror Material Pyrex equivalent for primary and secondary mirrors
Primary mirror thickness 37mm (approx. 1:8 thickness ratio)
Secondary mirror thickness 11mm
Minor axis of secondary mirror 70mm
Tube material Steel
Focuser 2” Crayford, includes 2” extension tube and 2”-to-1.25” adapter
Eyepiece / Magnification 32mm Omni Plössl, 47x
Finderscope StarPointer red-dot finderscope
Other Accessories StarSense Explorer dock, eyepiece rack, collimation cap, carry handles for OTA and
base, pointing knob, dust covers
Tripod Altazimuth Dobsonian base, adjustable altitude tensioning
Optical Tube Dimensions 56” x 14” diameter
Optical Tube Weight 49.8 lbs.
Base Dimensions 25” x 25” x 29”
Base Weight 33.8 lbs.
Total Telescope Kit Weight 83.6 lbs.
SPECIFICATIONS