[Loadstone] solar calculations
monty at loadstone-gps.com
monty at loadstone-gps.com
Thu Oct 25 21:27:51 BST 2007
We have been evaluating a couple of solar/lunar azimuth formulas for
potential inclusion into a future version of Loadstone. Stay tuned!
On Thu, 25 Oct 2007, Paul Woffenden wrote:
> Hello Shawn and All,
> Most of the information from your program looks very useful. Not sure what
> units the heliocentric (sun-to-earth) distance is in though; this is
> presently just less than one Astronomical Unit which is 93 million miles.
> As regards a solar azimuth, the 24-hour day is the time taken for the Earth
> to rotate once; which results in the Sun completing a circle of 360 degrees.
> If we divide 360 by 24, we of course get 15 degrees per hour; which would
> give you an approximation for solar azimuth -- 360 degrees at midnight and
> 180 degrees at noon. However there are many factors which pull and push the
> azimuth to either side of this average value of 15 degrees and I am
> currently trying to find formulae which take these into account. The best
> program on a computer for really exact solar/lunar information is RedShift;
> which has the advantage that it outputs information numerically as well as
> pictorally so it works with a screen reader such as JAWS.
> I am tweaking my Pascal code to try to get my values to agree with those
> output by Redshift and will let you know as soon as I have any more
> Really precise astronomical calculations use matrices; but my mathmatical
> knowledge isn't really up to this - I'm a lawyer not a mathematician hehe.
> The best book on these formulae is called Positional Astronomy; but my
> scanner won't read the symbols so its rather a slow process.
> Hope this helps.
> Best regards.
> Paul Woffenden
> ----- Original Message -----
> From: "Shawn Kirkpatrick" <shawn at odyssey.cm.nu>
> To: <loadstone at loadstone-gps.com>
> Sent: Thursday, October 25, 2007 9:14 AM
> Subject: [Loadstone] solar calculations
>> This message is for those people that want Loadstone to have a sunrise,
>> sunset, moon phase, etc. calculator.
>> I have some code on the pc that outputs a lot of information about these
>> things. Not knowing much about this stuff I'm not sure what we'd want as
>> output or the best way to represent it.
>> The output from my program is as follows:
>> local time: wed oct 24 23:52
>> timezone: -700
>> latitude: 49.2251716
>> longitude: -122.9915750
>> moon age: 14.08
>> moon visible percentage: 98.70
>> moon cycle percentage: 46.37
>> moon is visible
>> today's moonrise: 17:08
>> today's moonset: 05:47
>> moon azimuth: -3.42
>> moon altitude: 51.15
>> moon distance: 56.16
>> moon right ascention: 01:02:34
>> moon declination: 10.41
>> sun distance: 23350.68
>> sun right ascention: 13:57:20
>> sun declination: -11.99
>> Eccentricity: 0.02
>> Obliquity: 0.41
>> Ecliptic Long: 3.69
>> today's sunrise: 07:47
>> today's sunset: 18:05
>> Some of the information is very obvious but some just isn't. There's a
>> asimuth but no sun azimuth. Is it possible to calculate this from some of
>> this other information?
>> Any help or suggestions on how to use this information would be welcome.
>> Loadstone mailing list
>> Loadstone at loadstone-gps.com
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