SunPosition calculations online

**sunposition** · 2-Jan-2008, 04:48

Originally Posted by Leonard Evens

I stick with what I said. I don't think many LF photographers would find it worthwhile paying for this software when there are other free alternatives, such as Jeff Conrad's calculator, available at lfphoto.info, which are as well suited or better for their needs.

You mean it's hosted on: http://www.largeformatphotography.info
OK, I understand now.

Originally Posted by Leonard Evens

I also still don't see why you left Chicago, Illinois out of the list of sites available for free. After all, it is hardly a small uninteresting city where few people live. I bet many other important locations were also omitted.

I am sorry you can't understand why most of the important locations are omitted from the non members area!

I could go into a long answer here but to be honest, I will leave it up the users preference... as I have said a couple of times now.

**Joseph O'Neil** · 3-Jan-2008, 07:04

Not to insult anybody, but this whole thread has me puzzled. This kind of information has been freely available on various software platforms in many astronomical/planetarium programs for a while. For example:
http://www.midnightkite.com/software.html
http://freeware.intrastar.net/planetarium.htm
http://www.r-clarke.org.uk/astrosoft1.htm

..and there are more. The software is not all that hard to write - I did it once myself many moons ago when I used to program a bit in turbo pascal. Point is, determining basic sun and moon positions for any given time and lat & long. is the basic staple of any planetarium program, and I've had software that can do this since the days of the Commodore 64. Today, to get you lat & long, all you have to do is look it up on Google maps, punch in the location & save it in your planetarium program, and away you go.

joe

**Winger** · 3-Jan-2008, 07:34

http://aa.usno.navy.mil/data/docs/AltAz.php

**Leonard Evens** · 3-Jan-2008, 15:16

Joseph,

I was trying to make just your point, and in addition there is a link on this very web site to such a calculator.

On a vaguely related matter, do you have some good references which explain the mathematics behind the Equation of Time and related matters? I've just read "Marking Time" by Duncan Steel, which I found fascinating. It has appendices which explain it pretty well in words, but, as a mathematician, I am curious about the analytic details.

**BrianShaw** · 3-Jan-2008, 15:22

Originally Posted by Joseph O'Neil

Not to insult anybody, but this whole thread has me puzzled.

I've been puzzled since the first reply. What is all the emotion about? I have no need for such data, and found it real easy to think "thanks, but no thanks". It is all very puzzling to me.

**Joseph O'Neil** · 4-Jan-2008, 06:27

Originally Posted by Leonard Evens

On a vaguely related matter, do you have some good references which explain the mathematics behind the Equation of Time and related matters? I've just read "Marking Time" by Duncan Steel, which I found fascinating. It has appendices which explain it pretty well in words, but, as a mathematician, I am curious about the analytic details.

Hi;
Not exactly what you are looking for, but try and find a book called "Astronomical Algorithims" by - I think from memory - Jean Meesus. It was written about 15 years ago, and is a large collection of algorithims for anyone wanting to write their own software under any language.

It does not deal specifically with time, but I think you might enjoy it as it relates to time, movement of celestial bodies, different measurements of time, etc.
good luck
joe

**Leonard Evens** · 4-Jan-2008, 13:58

Originally Posted by Joseph O'Neil

Hi;
Not exactly what you are looking for, but try and find a book called "Astronomical Algorithims" by - I think from memory - Jean Meesus. It was written about 15 years ago, and is a large collection of algorithims for anyone wanting to write their own software under any language.

It does not deal specifically with time, but I think you might enjoy it as it relates to time, movement of celestial bodies, different measurements of time, etc.
good luck
joe

Thanks for the reference. It turns out to be Jean Meeus, and I found a copy for about $16 at Powell Books.

**sunposition** · 5-Feb-2008, 05:25

Just to update this thread:

The SunPosition domain has been changed to: http://sunposition.info

Because of the popularity of the SunPosition widget we have had to change our domain name, this is because of an excessive number of requests to the domain from our widget which in turn was creating an excessive load on the server. Changing the domain was the only solution available to us to combat this problem.

The SunPosition service is now available at the above domain.

For SunPosition widget users: At the time of posting the SunPosition widget will be disabled as the URL's used for calculation data pickup will have been shut down, we are currently working on an updated version of the widget that will be modified to help the server cope with such an excessive number of requests.

Regards
sunposition