Dorr DANUBIA ATLAS 2000 Bedienungsanleitung Seite 23

Unlock the R.A. clutch and rotate the mount in R.A. until 'November 1' (long line between 10 and 11) on the
calendar dial is lined up with '0' (midnight) on the 24-hour clock dial, then lock the clutch again (Fig.k2).
Loosen the three polarscope alignment screws. Look into the polarscope and you will see a crosshair with
a circle surrounding it and a smaller circle off on one of the arms (Fig.k3). Turn the polarscope until the little
offset circle is at the bottom and then slide it into the polarscope holder, lined up with the zero on the clock
dial. Insert the polarscope far enough so that later it will not interfere with the protective cap. Once you have
it inserted you will have to centre it. The easiest way to do this is to lower the mount head in azimuth and
sight on a distant object in daylight. This may involve taking out the latitude t-screw, shortening one leg, or
both to get the head down low enough. After you have done this unlock the R.A. clutch again and rotate the
mount back and forth in R.A. while keeping your target in view. The idea is to gently tweak the three alignment
screws, while rotating the mount, until the target remains at the centre of rotation. This shouldn't take long
and after that keep the plastic cap on to protect it from getting bumped off alignment. Set the azimuth of the
mount back to the correct latitude.
Using the polarscope
1. Now about the numbers "E 20 10 0 10 20 W". First, you need to find your present Longitude. You can do this
by consulting a map, chart, GPS, etc. The idea is to find how far east or west your viewing site is from the
reference meridian for your time zone. For example, the Longitude of Vancouver, BC is 123° and the refe-
rence meridian for the Pacific Time Zone is 120°, so the setting will be 3° W. The lines on the dial are 5°
apart so rotate the silver dial until the indicator on the black collar points between the zero and 5° line. If
you observe from a significantly different longitude, this setting will have to be changed.
2. At your viewing site, set the mount (without weights and scope) facing North. Adjust it to a convenient
height for viewing and carefully level it. Unlock the DEC. clutch and rotate to DEC. 0°, then lock the DEC.
clutch. Remove the cap from the bottom of the RA axis shaft and the plug from the top.
3. Set the black 24-hour clock dial so that the hour '0' aligns with the top indicator, and lock it in place with
the setscrew. Remember this dial is a clock face running from 0-23 hours. Northern hemisphere users use
the top row of numbers and all times are in Standard Time. Do not use Daylight Saving Time for the fol-
lowing setting
4. Unlock the R.A. clutch, and rotate the mount in R.A. until the current date on the silver calendar dial, is
aligned with the current time using the black 24-hour clock dial (Standard Time), then lock the R.A. clutch.
5. Using only the latitude adjustment t-screws for up and down, and the azimuth adjustment off-set screws
on the north side of your mount for left-right, centre Polaris in the little offset circle. You may have to shine
your red flashlight at an angle across the front to illuminate the crosshair or better yet have a friend hold
the light while you do the adjustments.
6. Lastly, loosen the top setscrew, unlock the R.A. clutch, put on the counterweights and then the scope and
finally adjust the balance position of the counterweight.
7.
8.
09 | POINTING YOUR TELESCOPE TO CELESTIAL OBJECTS
A German Equatorial mount has an adjustment, sometimes called a wedge, which tilts the mount's polar axis
so that it points at the appropriate Celestial Pole (NCP or SCP). Once the mount has been polar aligned, it
needs to be rotated around only the polar axis to keep an object centred. Do not reposition the mount base or
change the latitude setting. The mount has already been correctly aligned for your geographical location (ie.
Latitude), and all remaining telescope pointing is done by rotating the optical tube around the polar (R.A.) and
declination axes. A problem for many beginners is recognizing that a polar-aligned, equatorial mount acts like
an alt-azimuth mount which has been aligned to a celestial pole. The wedge tilts the mount to an angle equal
to the observer's Latitude, and therefore it swivels around a plane which parallels the celestial (and Earth's)
equator (Fig.m). This is now its "horizon"; but remember that part of the new horizon is usually blocked by the
Earth. This new "azimuth" motion is called Right Ascension (R.A). In addition, the mount swivels North(+) and
South(-) from the Celestial Equator towards the celestial poles. This plus or minus "altitude" from the celestial
equator is called Declination (Dec).
Pointing to the NCP
For the following examples, it is assumed that the observing site is in the Northern Hemisphere. In the first
case (Fig.n2), the optical tube is pointing to the NCP. This is its probable position following the polar-alignment
step. Since the telescope is pointing parallel to the polar axis, it still points to the NCP as it is rotated around
that axis counter-clockwise, (Fig.n1) or clockwise (Fig.n3).
Fig.k2
Fig.m
Right
Ascension
Meridian
Line
Plane of local horizon
Fig.n
23
Setscrew
Indicator
Time: 24:00 (Midnight)
Date: November 1
Polarscope holder
Polarscope-
alignement screw
Polarscope
Fig.k3
Equatorial Mount
(Northern Hemisphere)
Zenith
Mount aligned on
North Celectial Pole
Object you
are viewing
Declination
Plane of Celestial
Equator
Celestial Pole
Latitude
Apparent
movement
of stars