2006 Dobsonian Equatorial Telescope Project

Here you will find the stages of the Dobsonian Equatorial modified telescope for the spring 2006 astronomy lab.

Watch as the Dobsonian Telescope parts are created and assembly begins.

Figure 1: This is about what you want to build to hold the new 6"f8 telescope

Study up on standard telescope mounts. There are many types but they all fall into Azimuth-Elevation movement, or Equatorial Movement. You need to understand both.

The standard Dobsonian uses Azimuth-Elevation motion. This i cheap to build and does not require any angled pipes or heavy pieces. The Dob telescope sits on top of a rotating Azimuth (AZ) table. The AZ table top can only rotate horizontally left and right. The telescope tube an rotate in Elevation (EL) up and down on top of the Dob box.

This AZ motion will not track stellar object as they appear to move across the the sky. The Dob has to be moved in both AZ and EL, to track a star. This is a difficult thing to do by hand and by automated motors.

The best type of telescope mounts are the Equatorial type. This mount has two axis that are perpendicular to each other. One of the axis, Right Ancession (RA) or North Polar Axis, points near the North Polar Star, which is the Earths Rotation axis. The other telescope axis is called Declination since it only moves up and down the sky from +90 to -90 degrees. The RA axis of your equatorial telescope will track the east-west motion of the stellar objects. So all you have to do once you fine your object in the eyepiece is move the telescope Westward to compensate for the Earths rotation Eastward. This is a very easy method of tracking the heavenly objects. This is used by most all the telescopes less than 200" in diameter.

So, your mission should you choose to accept it, is to design a method to tilt the Dobsonian AZ-EL mount up on its side at the latitude of your position on the earth so that the AZ axis is now converted into a North Polar RA axis.

Good designing and assembly.

To find information on Dobsonian Telescopes go to Google.com or other search engines and use key words like "Dobsonian", "Dobsonian Telescope", "Dobsonian Mount", "Dobsonian Equatorial" and see if you find other information.

The wedge design for this telescope is not a new idea, but the method of making it rotate using the pvc 4" pipe pieces wont be found on any other telescopes.

Adding a drive motor to turn the Equatorial polar axis would be a great addition to the Dob. See if you can come up with a set of pullies using fishing leader wire wrapped around the pullies and a small mortor of XXX rpm (revolutions per minute) to make the Dob polar axis turn to counter act the Earths movement Eastward.

Good Designing.

Send your ideas to joeastro@aol.com