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Solar astro azimuth
I know it??s been asked about before, but??
Is there a proper astro azimuth reduction program out there?
For no good reason I do a lot of solar azimuths. And I reduce my observations in a spreadsheet, using MICA ephemeris, that I wrote a few years ago. But I??d like to compare my output to a current published program.
I do have a working copy of Elgin & Knowles Astro83, dated 1996, which is clunky and 27 yrs old. My output differs from E&K by only 4?, but it??s god awful to use as it??s a classic DOS exe.
Just wondering if there is a survey grade current program, or is solar observation that far removed from land surveying.
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15 Replies
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It has a long time since I used MTEN. The link you provide is to a suite of programs developed to perform reductions/computations of classical (optical) observation data.
My best recollection of its operation is that it requires the creation of input files consistent with the Horizontal Blue Book. Pretty sure there is no ephemeris included.
Doing a search from the NGS home page fails to find links to “MTEN.” There was a manual.
I may dust off a PC box and try to test the program.
While there is a renaissance in astronomical observations due to its use in deflection of the vertical studies in support of geoid modeling, among surveyors it remains an “ancient art” deemed obsolete.
On the many issues related to the determination of azimuth (and more) from optical observations, I would still recommend Mackie’s “The Elements of Astronomy for Surveyors.” My copy is the ninth edition published in1985. ISBN is 0-85264-244-X.
There is also a digital version of Chapman’s 1919 “The Elements of Astronomy for Land Surveyors” here: https://archive.org/details/elementsofastron00chaprich/page/184/mode/2up?view=theater
Also check UNB’s lecture notes for geodetic astronomy content.
BTW, the US NGS has developed a theodolite-based system for astronomical observations (similar to Daedalus). See:
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@GeeOddMike No one else was participating, so I searched your previous link to the NGS webpage
and found that solar azimuth software package. Absolutely no clue what’s in it.
We appreciate the links you provide.
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Ah cool…following along
ive been pursuing this for a little while in the park and backyard with my sokkia tm-1A
Still haven’t figured out all the pieces yet
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I have created an excel spreadsheet to reduce the observations. And loaded a year of ephemeris data. It’s a complicated thorough computation. But testing never ends
However I had some doubts in my excel sheet. I’ve reduced several of the observations in Elgin & Knowles Astro83. The output from E&K is quite similar to my computation, 3-4”
I have several distant radio antennas. My issue is morning observations returns 7-12” larger (CW) azimuths than afternoon observations. (Which is also returned by E&K Astro83.)
It appears that there are few if any current software options.
Now that evening temps are not so cold I’ll be using stars.
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All versions of Carlson Survey that I’ve used have Solar Observation under the Cogo menu.
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My issue is morning observations returns 7-12” larger (CW) azimuths than afternoon observations.
Are you using time or altitude method? The latter would be sensitive to refraction, which is hard to nail down.
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hour angle method. Altitude method is not worth anything.
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Could the top of your favorite tower move that much as the sun heats one side or the other?
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I suppose you are familiar with Jerry Wahl’s “Revenge of the Altitude Solar”
https://www.cadastral.com/papersl1.htm
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Yes that had occurred to me. Even over short time of an hour there seems to be some arcseconds of oscillation
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I’ve used Stellarium to check my Polaris calculations. Haven’t used it for the sun.
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