31
1.
With the NexStar set up outside and attached to an equatorial wedge, rotate the tripod so that the fork arms are
pointed towards north (see figure 6-3).
2.
Power on the telescope and scroll through the alignment choices until
EQ North Align
(or
South
for the southern
hemisphere) is displayed and press ENTER.
3.
The NexStar will automatically level the telescope tube perpendicular to the fork arms to find its internal
downstop. It will use this information to accurately position the tube parallel with the fork arms for polar
alignment. To improve the accuracy of your polar alignment, see section on
Calibrating Level
above.
4.
With the telescope in its downstop position (the tube perpendicular to the fork arms), the hand control displays the
message
Find Meridian
. Manually rotate the telescope in azimuth (R.A.) only until the tube is pointed up at the
meridian (see figure 6-4) and press Enter.
5.
The telescope tube will now position the tube so that it is parallel with the fork arms (90º declination), and ready
to be polar aligned. The NexStar will also rotate itself 180º in azimuth so that the finderscope will be positioned
on the top of the optical tube.
6.
Move the tripod and wedge so that the fork arms (and tube) are pointed at the celestial pole. For help in finding
the true celestial pole and polar aligning the NexStar, see the sections on polar alignment methods later in this
chapter.
7.
Once the telescope is polar aligned, the NexStar will ask you to choose two alignment stars from the displayed list
and slew the telescope to each star for alignment. For more information on aligning the NexStar with the sky, see
the
2-Star Alignment
Procedure in the
Hand Control
section of the manual.
F
F
F
F
F
F
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In each hemisphere, there is a point in the sky around which all the other stars appear to rotate. These points are called the
celestial poles and are named for the hemisphere in which they reside. For example, in the northern hemisphere all stars
move around the north celestial pole. When the telescope's polar axis is pointed at the celestial pole, it is parallel to the
Earth's rotational axis.
Many methods of polar alignment require that you know how to find the celestial pole by
identifying stars in the area. For those in the northern hemisphere, finding the celestial
pole is not too difficult. Fortunately, we have a naked eye star less than a degree away.
This star, Polaris, is the end star in the handle of the Little Dipper. Since the Little Dipper
(technically called Ursa Minor) is not one of the brightest constellations in the sky, it may
be difficult to locate from urban areas. If this is the case, use the two end stars in the
bowl of the Big Dipper (the pointer stars). Draw an imaginary line through them toward
the Little Dipper. They point to Polaris (see Figure 6-6). The position of the Big Dipper
changes during the year and throughout the course of the night (see Figure 6-5). When
the Big Dipper is low in the sky (i.e., near the horizon), it may be difficult to locate.
During these times, look for Cassiopeia (see Figure 6-6). Observers in the southern
hemisphere are not as fortunate as those in the northern hemisphere. The stars around the
south celestial pole are not nearly as bright as those around the north. The closest star
that is relatively bright is Sigma Octantis. This star is just within naked eye limit
(magnitude 5.5) and lies about 59 arc minutes from the pole.
The north celestial pole is the point in the northern hemisphere around which all stars appear to rotate. The
counterpart in the southern hemisphere is referred to as the south celestial pole.
Definition
Figure 6-5
The position of the Big
Dipper changes throughout
the year and the night.
Summary of Contents for NexStar 11
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