Levenhuk Skyline PRO 150 MAK [16/40] Tracking celestial objects

When observing through a telescope, astronomical objects appear to move slowly through the

telescope's field of view. When the mount is correctly polar aligned, you only need to turn the

R.A. slow-motion control to follow or track objects as they move through the field. A R.A. motor

drive can be added to automatically track celestial objects by counteracting the rotation of Earth.

The rotation speed of the R.A. drive matches the rotation rate of Earth for stars to appear

stationary in the telescope eyepiece. Different tracking speeds are also available in some models.

A second drive can be added to give Dec. control which is very useful for astrophotography.

The quickest way to find objects is to learn the constellations and use the finderscope, but if the

object is too faint you may want to use setting circles on an equatorial mount. Setting circles

allow you to locate celestial objects whose celestial coordinates have been determined from star

charts. Your telescope must be Polar aligned and the R.A. setting circle must be calibrated before

using the setting circles. The Dec. setting circle was calibrated at the factory and no additional

calibration is required for it.

The telescope's R.A. setting circle is scaled in hours, from 1 to 24, with small lines in between

representing 10 minute increments. The upper set of numbers applies to observations in the

Northern Hemisphere, while the numbers below them apply to observations in the Southern

Hemisphere.

Loosen the Dec. lock knob and rotate the telescope tube until the pointer on the setting circle

reads 90°. Retighten the Dec. lock knob. Loosen the azimuth lock knob and move the mount so

that the R.A. axis points roughly at Polaris. Use the two azimuth adjustment knobs above the "N"

to make fine adjustments in azimuth if needed. For more accurate alignment, look through the

finderscope and center the Polaris on the crosshairs using the azimuth and latitude adjustment

knobs.

After a while you will notice your target drifting slowly North or South depending on the direction

of the pole relative to Polaris. To keep the target in the center of the view, turn only the R.A.

slow-motion control.

After your telescope is polar aligned, no further adjustments in the azimuth and latitude of the

mount should be made in the observing session, nor should you move the tripod. Only movements

in R.A. and DEC axis should be made in order to keep an object in the field.

In the Southern Hemisphere you must align the mount to the SCP by locating its position with star

patterns, without the convenience of a nearby bright star. The closest star is the faint 5.5-mag.

Sigma Octantis which is about one degree away. Two sets of pointers which help to locate the SCP

are α and β Crucis (in the Southern Cross) and a pointer running at a right angle to a line

connecting α and β Centauri.

Tracking celestial objects

Setting (calibrating) the R.A. setting circle

In order to set your Right Ascension circle you must first find a star in your field of view with

known coordinates. A good one would be the 0.0 magnitude star Vega in the Constellation Lyra.

From a star chart we know the R.A. coordinate of Vega is 18h 36m.

Loosen the R.A. and DEC. lock knobs on the mount and adjust the telescope so that Vega is

centered in the field of view of the eyepiece. Tighten the R.A. and DEC. lock knobs to lock the

mount in place. Now rotate the R.A. setting circle until it reads 18h36m. You are now ready to use

the setting circles to find objects in the sky.