Aligning the r.a. setting circle – Celestron XLT series User Manual
Page 28
28
A
A
l
l
i
i
g
g
n
n
i
i
n
n
g
g
t
t
h
h
e
e
R
R
.
.
A
A
.
.
S
S
e
e
t
t
t
t
i
i
n
n
g
g
C
C
i
i
r
r
c
c
l
l
e
e
aps (#93722) or consulting a current
astronomy magazine.
nd easy to look up.
3.
o
e field. If not, find it and center it.
4.
5.
rdinates of the star.
6.
t
with the R.A. indicator (the zero mark on the vernier
ly. If the circle does not move freely, loosen the
a star each time. Instead, you can use the
coordinates of the object you are currently observing.
Once the
accuracy
ly related to the accuracy of your polar alignment.
1.
elect an object to observe. Use a seasonal star chart to make sure the object you chose is above the
horizon. As you become more familiar with the night sky, this will no longer be necessary.
2. Look up the coordinates in a star atlas or reference book.
3.
d the telescope and release the DEC clamp.
4.
ve the telescope in declination until the indicator is pointing at the correct declination coordinate.
5.
k the declination clamp to prevent the telescope from moving.
6.
old the telescope and release the R.A. clamp.
7.
ove the telescope in R.A. until the indicator points to the correct coordinate.
Before you can use the setting circles to find objects in the sky you need to align the R.A. setting circle.
The declination setting circle is aligned during the process of polar alignment.
In order to align the R.A. setting circle, you will need to know the names
of a few of the brightest stars in the sky. If you don’t, they can be learned
by using the Celestron Sky M
Figure 4-6
To align the R.A. setting circle:
1. Locate a bright star near the celestial equator. The farther you are from the celestial pole the better your
reading on the R.A. setting circle will be. The star you choose to align the setting circle with should be a
bright one whose coordinates are known a
2. Center the star in the finderscope.
Lo k through the main telescope and see if the star is in th
If you purchased an optional motor drive, start it now so that it will track the star.
Look up the coo
Ro ate the circle until the proper coordinates line up
scale). The R.A. setting circle should rotate free
thumbscrew to the right of the scale.
NOTE: Because the R.A. setting circle does NOT move as the telescope moves in R.A., the setting circle
must be aligned each time you want to use it to find an object. This holds true even if you are using an
optional motor drive. However, you do not need to use
setting circles are aligned you can use them to find any objects with known coordinates. The
of your setting circles is direct
S
Hol
Mo
Loc
H
M