Over 30 yrs ago, we would always attend survey conventions. There was one Jim Scott that looked a little like the surveyor in "the last traverse point" cartoon.
The topic at hand was basis of bearings.
This is from memory, and any errors or misunderstandings are mine.?ÿ ?ÿSo...
Jim was using the altitude method to determine bearings. Another fellow was using Dr Knowles ephemeris. We had been using Dr Knowles ephemers, and we felt we could get bearings within 20"regularly. So as they argued, we obviously did not agree with Jim Scott. Jim said "it was impossible to get bearings within 2 arc minutes". This whole argument went on, and I never got to the bottom of the matter. Jim was a super nice guy. But I never got to the bottom of the whole affair. The arguments have been sitting on my desk all this time (mentally speaking).
I recently tied into some of dad's work, that was based on "grid north" by solar observations. It fits my GPS by 21". This jogged my memory.?ÿ
Anyway, did I misunderstand the issues? Or is there an altitude method to perform a sun shot?
If so, how does it work?
I really miss the fun and fellowship in the halls, at Survey conferences. That's where the value was.
The fall ASPS conference is coming up. I may attend it.
Anybody else going?
I wish I had the Jim Scott argument settled. Then I could "put it away".
Nate
I assume you know the original name for Arkansas was Noah.
He invented the saw in order to construct the ark neatly.?ÿ The explorers found so much water in the delta region they thought it would be a great place for Noah to settle with his ark and saw.?ÿ Then the hill folk moved in.?ÿ Nothing has been the same ever since, including the name of the State.
That's baloney, beef balogna, or beef jerky. I wish I had a extra bag of pepper beef jerky. Should I tell you where Kansas got its name? Maybe I can make something up.... It's related. This is our-Kansas. Aka Arkansas. I guess that one is your-Kansas!
😉
Nate
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To get an azimuth from a sun shot, you can use a source of very accurate time and some calculations from tables
OR you can use knowledge of the sun's azimuth when it is at a measured altitude and some calculations.
http://www.cadastral.com/papersl1.htm
There is Kansas, it seems to me the other state should be Aren??tKansas.
We did this in school except we used a total station with the sun lense, accurate clock, etc.?ÿ Interesting idea for sure but I remember thinking at the time that I doubt anyone did this in the real world anymore.
Nate, I think you may be referring to the "Equal Altitudes" method of a sun shot where the split of two shots, one before noon and one after noon at the same altitude, gives you a south direction.?ÿ No clock or tables are needed, just a lot of patience.
Well, at least surveyors argue over meaningful things. I used to work with actuaries. One day, one asked the question, why does actuaries use the end urinal? His answer was at the end urinal there is 50% less chance of being peed on.
But then another actuary pointed out that, since it is possible for one to pee on oneself, there's really only a 1/3 less chance of an unpleasant experience. What followed then was a discussion of whether the probabilities were equal; is there a greater chance that you will pee on yourself than that you will be peed on by your neighbor?
I left when they started discussing putting together a study.
I've never quite satisfied myself as to whether the north of NAD83/GPS is the same as the north of any emphemeris. Or of any other flavor of NAD83. Or NAD27. In any case, your 21" comparison seems to vindicate your method.
Basis of Bearings is an argument that get me going. I could not care less what your basis of bearings is. I have never, not once, had different bases of bearing affect the ultimate placement of my monuments one way or the other. Bearings are just a convention for annotating angles.?ÿ
Now, basis of coordinates (ie/ projection and datum) is another matter.?ÿ?ÿ
You could pee on yourself in any stall so that situation is irrelevant.?ÿ End stall wins.?ÿ ?????ÿ
Nope.?ÿ The State east of Oklahoma came first.?ÿ The State north of Oklahoma came later.
https://www.businessinsider.com/why-we-pronounce-kansas-and-arkansas-differently-2014-2
?ÿ"Equal Altitudes" method?ÿ
There's that, too, but I think they were probably referring to the method studied in the Jerry Wahl paper linked above.
Thank you for finding and posting that link to that article. I do believe that was what was being argued.
I always preferred grid brgs to geodetic.
N
@bstrand?ÿ
Agreed. The argument, though, was over the absolute magnitude of the probabilities, whether self-anointing, being anointed from the left and being anointed from the right have equal probabilities. I can say now, though, that if a bunch of old men are standing shoulder to shoulder, the probability of someone getting wet is high.
Of course, that was back in the immodest days when there were no barriers between receptacles. Down in Chapel Hill, where the school of public health is world-renowned, immodesty apparently was still the norm back in 2016: Those Dean Dome Pee Walls (bobleesays.com). (Please ignore the snide comments about a past chancellor; that's how we resolve differences in NC.) I haven't been to the Dean Dome since circa 1998 though, so I really can't speak to the current situation.
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I think you might change your attitude about that if you're working in a Lambert system near the E-W edges of the zone.?ÿ
@holy-cow well then the only way to fix this is change Arkansas to Kansas and change Kansas to Aren??tkansas
@mightymoe There are exceptions. My experience is limited to .... (Get ready for it)
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A R Kansas.
🙂
N
@bill93 Back in the 60's I learned to listen to the "tone" that would sound on the AM radio band at the top of the hour. I believe the tone was generated by an atomic clock from Cheyenne Mountain at NORAD base near Colorado Springs (at the time my brother worked there). I would check the second hand position of my watch corresponding with the moment of the tone to learn the adjustment bias. Used this accurate time, together with angle ties to top/bottom of the sun, and an ephemeris. Also did Polaris observations at night time. Polaris observations seemed to yield the best bearings.
@bill93 Back in the 60's I learned to listen to the "tone" that would sound on the AM radio band at the top of the hour. I believe the tone was generated by an atomic clock from Cheyenne Mountain at NORAD base near Colorado Springs (at the time my brother worked there). I would check the second hand position of my watch corresponding with the moment of the tone to learn the adjustment bias. Used this accurate time, together with angle ties to top/bottom of the sun, and an ephemeris. Also did Polaris observations at night time. Polaris observations seemed to yield the best bearings.
The tone was probably relayed by the station from WWV radio operated by the National Bureau of Standards near Ft Collins, rather than NORAD.
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