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EPHEMERIS
Where can find a solar Ephemeris for doing sun shots? I like to confirm my work.
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12 Replies
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Elgin and Knowles used to publish them. I think that the computerized version, drove them out of popular use. I see occasional ones sold as antiques… From 1987 etc.
N
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Jerry Wahl (@jlwahl) used to provide a very convenient one at cadastral.com but I don’t think he has done the last few years. His site recommended https://celnav.de/longterm.htm
which I haven’t used. You need a current value for delta T (on the order of 70 seconds) to get meaningful answers from sun shots, and I haven’t looked for that number. An approximate value would be good enough for Polaris, especially if near east or west elongation.
I once used a program called SPADE to do those calculations, so you might check if it is current.
There have been discussion of solars on this forum in prior years that might have some useful information. Try a search.
One discussion of methods is here
https://surveyorconnect.com/community/surveying-geomatics/solar-observation-method-comparison/
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I also still frequently do solar observations along with GNSS observations. Jerry Wahl no longer provides an ephemeris.
Try this link to the University of New Mexico, Kurt Wurm, Ph.D., P.L.S. for his ephemerides.
https://wordpress.nmsu.edu/kwurm/ephemrides/
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Where can find a solar Ephemeris for doing sun shots? I like to confirm my work.
Just what would you be confirming?
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I survey in grid using my JAVAD TRIUMPH-LS GPS. Then I rotate my survey to True North in my COGO program (Traverse-PC). I test the rotation every way I know how. I would be confirming the rotation with a sun shot. I have used the TRIUMPH-LS for about 5 years but it still so awesome to me that I feel lost. I was a rodman helping with sun shots in 1958. Also, I have keep Epidermis on file for many years. I consider Nate the Surveyor to be one of the greats using the equipment that I use.
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I have keep Epidermis on file for many years.
Autocorrect strikes again!
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@ The Mule
Just curious, how does that particular data flow work?
Survey in spc, plat in geodetic, ground coords, I assume?
Where does cogo, and data annalysis happen?
I’m doing often all of my work with a 50k,50k system. Then, make another crd file, with spc. This way, I have both. This way I can place spc coord on my plat, with metadata.
N
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I am glad that a fellow JAVAD user will read my work flow. I work in spc because it is easier with the LS. After my first set-up, I can enter deed in geodetic. I realize the the ground/grid distances may not be perfect, but I think they are close at my elevation. I use COGO, ‘Direct’ to create a point (501) GEO North, 500′ from the point (10) that I will use for rotation. When I inverse in the LS, I get a grid bearing. I download to a flash-drive, and then to Traverse-PC. When I think that I am finished with the LS, I create a new duplicate job in Traverse-PC, but keep the old job so that I still have the spc. I rotate the new job, using the line 10 to 501, which shows the Grid bearing to North. Then to avoid the possibility of have coordinates that look like spc, I translate to 5,000/5,000. I check my work, by comparing some of the inverse Geo bearings in my LS to my Plat. Since I round off my Plat bearings to 5 seconds, I do not worry about a 1 second difference.
I can create points in Traverse-PC and move them to my LS, or I can move any part of my file to my HP 48. I used my Topcon 211 two times in 2018. I work one or two days a week when I want to, doing jobs that clients want me to do.
Thanks
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@the-mule try this https://mcraymer.github.io/software/spade/
Not sure it works on modern OS, I have a note I had to run in a DOSBOX in WIN7 and I don’t think I have used since WIN10, but if it works a very simple SOLAR software.
SHG
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Here is an old thread on the subject:
https://surveyorconnect.com/community/surveying-geomatics/solar-observation-program/
I know Javad is working on a version of sunshot software, for use with J-mate, his new camera based “total station”.
It does sunshots, automatically… According to the advertising.
Nate
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Spade doesn’t appear to run in WIN10 (or any 64bit OS), therefore if it still works would have to be run in a “dosbox” or on an older OS. For the heck of it, I just installed DOSBOX on a WIN10 64 laptop and was able to run SPADE using today’s date and it seems to work, although I can’t verify that it is working correctly.
SHG
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I like http://www2.unb.ca/gge/Pubs/LN49.pdf which is “Introduction to Geodetic Astronomy” by D.B. Thomson.
Many interesting issues when dealing with Celestial and terrestrial systems. See: http://iers-conventions.obspm.fr/conventions_material.php
Remember when working with astronomical observations for azimuth that astronomical and geodetic azimuths are related by the Laplace equation. In the US the NGS data sheets include this value.
Here is the Laplace correction for a point near me:
1 National Geodetic Survey, Retrieval Date = FEBRUARY 7, 2019 GR1809 *********************************************************************** GR1809 DESIGNATION - WILSON GR1809 PID - GR1809 GR1809 STATE/COUNTY- NV/CLARK GR1809 COUNTRY - US GR1809 USGS QUAD - BLUE DIAMOND (1982) GR1809 GR1809 *CURRENT SURVEY CONTROL GR1809 ______________________________________________________________________ GR1809* NAD 83(1994) POSITION- 36 05 37.10806(N) 115 29 02.32853(W) ADJUSTED GR1809* NAVD 88 ORTHO HEIGHT - 2155.2 (meters) 7071. (feet) VERTCON GR1809 ______________________________________________________________________ GR1809 GEOID HEIGHT - -26.656 (meters) GEOID12B GR1809 LAPLACE CORR - -18.97 (seconds) DEFLEC12B
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