My Digital Setting Circles

My quest to find Deep Sky objects has come a full circle.

ince 2005 I have been using Digital Setting Circles to find my way round the sky. This is the culmination of many years of using a Telrad, Finderscopes, Rigel Quikfinders.

Starhopping is a valuable skill to acquire, but sadly, does not allow you to see many objects in a night. So a move to setting circles was inevitable after seeing fellow observers use Argo Navis setting circles and the significant increase in objects observable in an evening.

Digital Setting Circles (DSCs) on an telescope are used to point the telescope at a particular object in the sky based upon the object's celestial coordinates. They are electronic devices which, when coupled with optical encoders which precisely measure the movement of the telescope on its axes, can tell you precisely where your telescope is pointed, or can guide you directly to an object you specify. All that is required is for the telescope to be aligned on two bright stars and then the software.


Current Setup July 2007

I am now, as of July 2007, using an Argo Navis, sold by Gary Kopff at Wildcard Innovations. After selling my StellarVue AT1010, I decided to upgrade the Ek Box to a commercial DSC.

Using the encoders from the Ek Box, I easily installed the Argo Navis to the top of the scope.

Photos of the install can be seen by clicking the Photo Album button bellow.

More Details to come!!


New Argo Navis DSC mounted high on the Scope


Previous Digital Setting Circles

In 2005 people were installing Dave Ek DSCs onto their scopes with great regularity due to Rudy Zondag putting these into the hands of New Zealanders. Rudy constructed me a set and I have never looked back. They are accurate and easy to use.

Dave Ek DSCs consist of;

Optical Encoders
Control Box
Computer or PDA

The encoders are mounted to the centre of both the Azimuth bearing and the Altitude bearing. The encoders then transmit the information on Alt/Az back to the Encoder box. My encoder box then can send the position information to a computer or Palm OS PDA. The computer can then display the exact position of the telescope on the screen. Likewise a Palm PDA using PalmDSC software can display the location of the scope relative to any object in the Night Sky.

The Palm is small and convenient, while the Computer using Skymap Pro v11 can graphically display the location on a star chart with crosshair. I tend to use the Palm more regularly than hooking up the computer. Both are very easy to use.

I hardly ever take the laptop with me anymore, just relying on the Palm and an set of Uranometria 2000 Second Edition star charts. Observing Lists are created and uploaded to the Palm for use at the telescope. The PalmDSC program allows any object to be entered. A recent modification to the Ek Box now allows the Ek Box to charge the rechargeable AAA batteries inside the Palm M100 series Palm OS PDA, this allows indefinate observing time when coupled with a 12V Gel Cell Battery.

So all that remains is the Rigel Quickfinder for pointing at the bright stars during alignment. There is no finder now, the 80mm StellaVue Refractor is seldom used at all.

Links to Related Pages.

Dave Ek DSCs Home Page

PalmDSC Software for Palm

ASCOM Communication Platform



Altitude Encoder and Arm
Cable attaches to the Hidden Encoder


COM Cables
RS232 Serial on the Left
Palm on the Right
Azimuth Encoder in Background


Palm M100 Series PDA
The Palm runs PalmDSC and connects to
a dedicated COM Port on the Ek Box DSC


Previous Finders

I have experimented with many ways to find objects over the many years.

The most recent configuation prior to the DSCs, I chose to use a Stellarvue 80mm AT1010, as my finder and have a University Optics erect image Diagonal which gives me a true 'binocular' view. I tried a few crosshair eyepieces then settled on a 24mm TeleVue Widefield eyepiece which gave me just on 3 degrees FOV. You can just see all three belt stars in the field of view. The 80mm also serves as a widefield telescope, as I have already mentioned, no crosshair eyepiece is necessary. The 80mm made the scope very heavy and had to be taken off the telescope every time the scope was dismantled. Time to align and the extra weight just made this set-up more of a chore than the benefits.

My 8 inch Celestron Dob had a Telrad installed on it. have used I relied on my old trusty Telrad and a widefield eyepiece to find my way round the heavens. When I built the 13 Inch Dob I wanted to use a finderscope to help speed up the starhopping process by not having to chop and change between eyepieces so often. I decided to stump up for a optical 8 x 50mm erect image finder.

The 8x50mm was excellent. There are many of these around and this served its purpose until Dave Moorhouse bought an Argo Navis, digital setting circles. I was sorely tempted into purchasing a set until I decided to piggyback a 80mm Short Tude refractor on the side of the Dob. This would give me a portible telescope for those occasions where I just wanted to observe a comet or something of that order.

May I suggest that you invest in a finderscope a set of Kendrick Dew Heaters, they are invaluable, as there is nothing more irritating than dewing up optics on you finder.

Finder Arrangement prior to the DSCs
Quikfinder, Stellarvue 80mm Refractor
Initial Finders at 13 Inch Dob First Light 2001
8 x 50mm Finder & Telrad 
Updated 4th July 2007