Polar Aligning The Mount - Celestron CGEM II Mode D'emploi

Polar Aligning the Mount

Latitude Scales
The easiest way to polar align a telescope is with a latitude
scale Unlike other methods that require you to find the
celestial pole by identifying certain stars near it, this method
works off of a known constant to determine how high the
polar axis should be pointed The CGEM II mount can be
adjusted from 15 to 70 degrees
The constant, mentioned above, is a relationship between
your latitude and the angular distance the celestial pole
is above the northern (or southern) horizon; the angular
distance from the northern horizon to the north celestial pole
is always equal to your latitude To illustrate this, imagine that
you are standing on the North Pole, latitude +90° The north
celestial pole, which has a declination of +90°, would be
directly overhead (i e , 90° above the horizon) Now, let's say
that you move one degree south — your latitude is now +89°
and the celestial pole is no longer directly overhead It has
moved one degree closer toward the northern horizon
This means the pole is now 89° above the northern horizon
If you move one degree further south, the same thing happens
again You would have to travel 70 miles north or south to
change your latitude by one degree As you can see from
this example, the distance from the northern horizon to the
celestial pole is always equal to your latitude
If you are observing from Los Angeles, which has latitude
of 34°, then the celestial pole is 34° above the northern
horizon All a latitude scale does then is to point the polar
axis of the telescope at the right elevation above the northern
(or southern) horizon To align your telescope:
1 Make sure the polar axis of the mount is pointing due
north Use a landmark that you know faces north
2 Level the tripod There is a bubble level built into the
mount for this purpose
3 Adjust the mount in altitude until the latitude indicator
points to your latitude Moving the mount affects the
angle the polar axis is pointing For specific information
on adjusting the equatorial mount, please see the section
"Adjusting the Mount "
This method can be done in daylight, thus eliminating the
need to attempt in the dark Although this method does
NOT put you directly on the pole, it will limit the number of
corrections you will make when tracking an object It will also
be accurate enough for short exposure prime focus planetary
imaging (a couple of seconds) and short exposure piggyback
astroimaging (a couple of minutes)
Polar Align using the Hand Control
The CGEM II mount has a polar alignment function called
"All-Star" Polar Alignment that will help you polar
align your telescope for increased tracking precision and
for astroimaging This feature allows you to choose any
bright alignment star to assist in accurately aligning your
telescope's mount with the North Celestial Pole Before
using the Polar Align feature, the scope must first be roughly
pointed towards north and should be aligned with three
stars in the sky See the "Latitude Scale" section for help
with finding north and adjusting the mounts latitude
Once your telescope is aligned on two stars and at least
one additional calibration star, slew the telescope to any
bright star in its Named Star database list For best results,
choose a polar alignment star that is high in the sky and near
the Meridian Try to avoid stars that are close to the west/
east horizon, directly overhead or too near the celestial pole
Once completed, press the Align button and use the Up/
Down buttons on the hand controller to select Polar Align
from the list
Align Mount – After performing a two star alignment with one
calibration star and slewing your telescope to any bright star
in the telescope's database, select the "Align Mount" option
The telescope will then slew away from and then back to the
same star
1 The hand control will ask you to re-center the star in the
finderscope and press ENTER
2 The hand control will ask you to accurately center the star
in your eyepiece and press ALIGN The telescope will
then "sync" on this star and slew to the position that the
star should be if it were accurately polar aligned
Note: For the most accurate alignment, it is best to use a
reticle eyepiece or a high power eyepiece to precisely center
the star in the field of view
3 Use the mount's latitude and azimuth adjustments to
place the star in the center of the eyepiece Do not use
the direction buttons on the hand control to position the
star Once the star is centered in the eyepiece, press
ENTER; the polar axis should now be pointed towards
the North Celestial Pole
ENGLISH | 25