Category Archives: Astronomy

What is an Equatorial Platform?

The slideshow attempts to explain simply how the idea of an Equatorial tracking Platform is derived from a classical driven Equatorial mount.

Essentially a tracking platform converts your Dobsonian mounted telescope into a motor driven polar aligned Equatorially mounted telescope system.

Many hundreds of these Equatorial Platforms have been built for Dobsonian mounted telescopes, and the theory works superbly in practice.

The Dobsonian mounted telescope, sits on a small platform which then rotates the whole telescope and its mount, and thus the telescope tracks celestial objects as they drift across the sky.

To work well equatorial platforms have to be very carefully designed and built to match the latitude of the observer, and then made with quality materials to quite close tolerances. They also need to be accurately driven, either by a precisely geared speed variable DC motor, or by a more complex electronically controlled stepper motor capable of providing accurately a sufficiently slow rotation speed.

The Watch House Equatorial Platform, of course, meets all of these Design Criteria.

Now, by driving the Platform relative to the groundboard, at a speed that matches the rate of the Earth’s rotation, the telescope tracks celestial objects keeping them in the eyepiece field of view for 10’s of minutes even at high or very high magnification powers eg 300x – 500x .

The overall North/South tilt of the platform when set up anywhere from 470 North to 570 North is only a maximum of 5 degrees from level.

The overall movement of the platform table , ie the East/West tilting motion as the platform tracks during one hour involves only a maximum of +/- 8 degrees from the mid-way horizontal & level position at each end of the tracking arc.

Watch House Platform tracking Arc

The above “stopped motion” animation shows the overall movement described by the Watch House platform over one hours tracking.


Because objects remain stationary in the eyepiece, you can observe much finer detail and fainter objects become a pleasure to observe.

Upgrade your Dobsonian mounted telescope with a Watch House Equatorial Platform and you will immediately enjoy the following:

No more nudging the damn scope to keep painstakingly located objects in the eyepiece, as your telescope + platform setup now tracks the stars!

Greatly reduced eye fatigue for the observer.

Much higher powers become comfortable for lunar, planetary and DSO observing, 300x to 400x becomes a routine pleasure and up to a theoretical 600x becomes possible, with the object remaining steady in the eyepiece.

Much finer detail is appreciated, as your brain processes an essentially stationary image.

Sketching becomes a pleasure, as objects now remain stable in the eyepiece as you move back and forth between eyepiece and sketch pad, even at high magnifications.

You can now use your scope for photography, with some limitations ( of course ! ) , including with the new generation of very reasonably priced integrating CCD cameras, see our photography pages for more information .

Go anywhere portability, as the Watch House Equatorial Platform weighs only 18lbs and is easily carried in 2 pieces, taking less than 5 minutes to set up and align in the field.

Additionally the Platform requires no external power supply, so no mains lead tethering you to the house, and no heavy & expensive 12v Powerpack to lug about either, just its own small 9v battery .