Eq-1/Eq-2 Mount Setting Circles - Omegon EQ-1 Mode D'emploi

3.5 EQ-1/EQ-2 mount setting circles

The best method of finding a celestial object with the telescope is to visually search for it using a finder scope or
a red dot finder. In this way you will learn the sky and, after some practice, be able to locate objects within a short
time. Nevertheless, an alternatively way is to search for an object using the setting circles on the telescope's two
axes. The sky, like the earth, is divided into a coordinate grid system. Each point can be described by coordinates.
In the case of the EQ-1/EQ-2 mount, these settings are approximate. If a celestial object is too dim or you are
having a problem finding it, the setting circles can help you. However, do not rely solely on this method but use
it as an additional tool. This class of telescope will not achieve a very high level of accuracy.
The setting circles
Now look at the setting circles a bit more closely. The RA setting circle has upper and lower scales, marked in
hours from 00:00 to 24:00, both of which are adjustable to 10 minute division lines. The upper scale is valid for
settings in the northern hemisphere and the lower for settings in the southern hemisphere.
The right ascension can be regarded as degrees of longitude on the celestial sphere. But since celestial objects
constantly move towards the west, this coordinate is not fixed but changes with time. The right ascension or the
hour angle of an object must be calculated for a certain time or set at the setting circles.
One likewise finds a setting circle at the declination axis which, unlike the RA setting circle, is marked in degrees.
This is involved with declination coordinates. It designates the height of an object above the celestial equator.
The 90° declination setting corresponds to approximately the height of the Pole Star. In contrast to the right
ascension, declination is always fixed and never changes.
Setting the setting circles
In order to set the setting circles to an object you must first calibrate them using a known star. For this, select a
bright easy to find star and put it into the telescope's field of view using the visual method above.
For example, you could use the star Alkaid in the Big Dipper (Ursa Major). Alkaid is the end star of the handle
in the Big Dipper and very easy to find. Adjust the mount so that Alkaid is in the field of view of your telescope.
Before starting this, make absolutely sure that your mount has been polar aligned as accurately as possible.
Get the coordinates of the reference star used from a star atlas. Alkaid has the coordinates: RA 13h 48m,
DEC +49° 15'
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