The US NGS has developed a new system to perform astronomical observations using a Leica TS60 robotic total station. The system's acronym is TSACS.
Details are here:
https://geodesy.noaa.gov/web/science_edu/presentations_library/files/geodetic_astronomy_at_ngs.pdf
To be used for deflections of vertical, astronomical azimuths and geoid studies.?ÿ
This new NGS system builds on systems like the less portable CODIAC and QDaedalus systems. Google them.
Note that the "ancient Wild T-3" was used for comparison.
Like all optical systems, it still requires a clear sky.
?ÿ
Yes, this is super cool.?ÿ?ÿ
Look at the T-4 on slide 10. Wowwww
From the last slide:
"Astronomic azimuths and deflections could be used to orient local surveys to the ITRF with higher precision than GNSS"
The fact that the system can be operated by a single person and takes less than an hour to get positioning within 0.2 arcseconds is pretty amazing.
I don't really NEED one of those systems. But I want one.
Look at the T-4 on slide 10. Wowwww
The only time I ever laid eyes on a T4 was in NGS HQ in Silver Spring. I'd love to have one, but I'd probably have to reinforce my floor in order to display it in my office.
I had a chance once to buy a T-4.?ÿ Passed.?ÿ Dumb! Dumb! Dumb!
Some more T4 pics here: https://auctionsouthwest.hibid.com/lot/1936-119741-792606/wild-heerbrugg-t4-120739-theodolite-us-1968
This is really fascinating. I like the "low-tech" approach of CODIAC even though it seems much more limited than robotic work.?ÿ
We (Javad) messed around with performing solar observations robotically a few years ago. Not exactly the same, but I bring it up because I think robotic astronomic observations are quite possible today and could be extremely accurate given digital time and position afforded by GNSS. I'm guessing the timing light is important because the timing on the shutter isn't known well enough?
Really good stuff.
One last question... is there a reason the scatter plot of the MS60 observations are somewhat sinusoidal? Could there be a pattern there? Since the X-axis isn't defined in the slide, perhaps it's just coincidence that the graph seems to take a shape.
The mention of the "antique Wild T-3" Theodolite?ÿ used by NGS brought back some old memory's of research done on comparison between the T-3,T-4 and the Kern DKM3 theodolites. Of the 3 theodolites the T-3 gave?ÿLESS accurate results.
The Geodetic Survey Squadron of the Air Force preferred the Kern DKM3 or the Kern DKM3A or Kern DKM3AX over the T-3.
Martin Popelka of TRW did a study and found the same thing; Kern DKM3 is better for azimuth determination than the Wild T-3
and that the T4 gave slightly better results than the Kern .
I don't know why NGS would used a T3 when a Wild T3000 would give much better results (electronic leveling).
If one wants to read a very interesting paper (which NGS must have forgotten about) see "Wobbles of the Horizontal Axis of a Theodolite" by Prof. L.A. Kivioja and J.E. Pettey. in Surveying and Mapping, Dec. 1973, pp. 481-490
JOHN NOLTON
As you say, not enough information in the graph for me. Only data for seven points are provided on graph. I suggest you direct your inquiry to Ryan.Hardy@noaa.gov
?ÿ
I have not yet tried to find your reference.?ÿ
That said, I am pretty sure NGS does not own any Kern theodolites but does have a lot of Wild T3 and T2 theodolites (and still some familiar with their use?).
Looking at reports from their IERS network site surveys I see they use two Leica TDM 5005s.?ÿ
You can contact the author of the presentation to determine why they used the T3 and whether he is familiar with your reference (Ryan.Hardy@noaa.gov).
Personally, I always liked a nice striding level when performing such work. Having been retired a decade and a half and not touched a theodolite ten years before then, I no longer claim expert status.
?ÿ
@geeoddmike?ÿ ?ÿNGS did own a DKM3A theodolite but your mention of the TDM would have been the instrument to use (I forgot they have one or two of them). Electronic leveling (2 axis compensator) is the way to go for azimuth; even over the striding level.
If you want to play with a T3 I can ship you mine, it's has a 2 minute micrometer (I like the 60 second micrometer myself).
?ÿ
I have a copy of the paper "Astro-Azimuth Comparative Studies With Wild T3, Wild T4, and Kern DKM3 Theodolites" which is what I think you are referring to, which is very interesting. After reading that several times, I wonder if residual mislevelment was a partial factor. I was surprised at the results, although the differences are not large there is a definite difference in the data, and they had plenty of data to compare.?ÿI am not sure if I am allowed to post a copy, not because it is classified or anything, but because I did have to pay to download it and maybe the AIAA has restrictions for that reason.?ÿ
I had used a T3 extensively for astro azimuths when I was hired to observe some azimuths at a defense contractor facility for IMU calibration. They had a Kern DKM3, I found it very easy to use and I particularly liked the "broken telescope" where you are always looking directly into the eyepiece on the side regardless of the vertical angle to the star, same as the T4 (which I have never used)?ÿ
Some more T4 pics here: https://auctionsouthwest.hibid.com/lot/1936-119741-792606/wild-heerbrugg-t4-120739-theodolite-us-1968
David Hoffart is an equipment dealer with Transit Works in Nebraska and Iowa. I met him at the Nebraska surveyor's conference. He's a great guy and was kind enough to bring numerous antique survey instruments to the convention, one of which was the T4. It was my first time to see one in person. It's an impressive piece of technology. I don't know for sure how much it weights, but I would not be surprised if it exceeds 100lbs. It's two pieces the base with its standards, and the scope with its trunnion, which is placed in a cradle in the standards. The cradle has bearings that ease rotation on the vertical axis. The base has a massive tribrach with rounded foot pads that rest in concave recesses in the heavy tripod. It doesn't bolt to the tripod like most modern theodolites and total stations. Sighting is through the side of the instrument so that high vertical angles are easy to view. It was a great pleasure to see it, to be able to help assemble it, and to be able to touch it and look through it. Dave went above and beyond bringing it to the conference. I could not imagine the effort required to get it to some of the high places in remote locations where these things were set up.
(I know the terminology I'm using to describe its parts is not correct, but it's the best way I know how to describe it).
?ÿ
?ÿ
?ÿ
