I have seen some dobsons on equatorial platforms with clock drives, I believe they can use setting circles in a more conventional manner.
http://www.equatorialplatforms.com/dobsonians.on.platforms.html Kim,
That totally makes sense to me. I didn't even think of a horizontal coordinates. Thanks for clearing that up with me. I figured I had something wrong and it was screwing me up.
So, basically, with a dobsonian, if you are to use setting circles, you will need to have a computer to help you determine where things are and what you are looking at.
Thanks.
Troy
On Sun, Apr 19, 2009 at 1:59 PM, Kim <kimharch@cut.net> wrote:
Oops - one more thing. I always rotate the scope first to the correct azimuth, then simply raise the scope to the correct altitude. It's that simple, but you must know the correct time and location for the coordinates to be of any use.
Kim
-----Original Message----- From: utah-astronomy-bounces@mailman.xmission.com [mailto:utah-astronomy- bounces@mailman.xmission.com] On Behalf Of Troy Davidson Sent: Sunday, April 19, 2009 1:35 PM To: Utah Astronomy Subject: Re: [Utah-astronomy] Dobsonian Setting Circles?
Erik,
I have seen that site and it is what got me thinking. But, I'm still confused how the altitude scale works. On an equatorial mount, if I point the scope at the celestial equator and then move it to an object to the far west that is on the horizon, the scope is still at 0 degrees on the celestial equator.
But, on a dobsonian, if I pointed the scope at the same object on the horizon, it will say 0 degrees. Then, if I turn the scope due south and keep pointing at the celestial equator, the altitude is no longer at 0 degrees. It's at 50 degrees, if I remember correctly.
This is the dilemma I am having. The azimuth is easy to deal with, but altitude is still screwing me up on how it would work on a dobsonian.
Thanks for the help.
Troy
On Sun, Apr 19, 2009 at 10:14 AM, <erikhansen@thebluezone.net> wrote:
Troy,
Have you looked at this website? It suggests refinements to an inclinometer.
http://www.homebuiltastronomy.com/ManualDobSettingCircles.htm
I would not ask John Dobson for his opinion on setting circles for Dobsonians.
Erik
Hello all,
I'm looking at adding some setting circles to my Dobsonian. The azimuth circle will be easy to handle on the base. I have found
sites
that allow you to print out whatever size you need.
But the altitude scale seems to be more of a problem. I can use an inclinometer to tell me the angle of my scope. A simple math problem and I would have my Dec. But, this will only work if the scope is directly pointing north or south. When the scope is pointing to an object that isn't directly north or south, then the math gets a bit harder.
I have seen digital setting circles, but those seem to start at $500. Is there a better way to handle setting circles, especially the altitude, on a Dobsonian?
Thanks.
-- ++++++++++++++++++ Troy Davidson
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