@john-nolton Not at all. I enjoy a good conversation
I??m am glad you enjoyed Ryans presentation. He has done a lot of work developing a field ready system. I was part of the GEMS survey with him in AK last fall. I wasn??t part of the astronomy crew, that??s way past my bedtime. I was there to do the GNSS observations along the line. Weather is a big factor, it??s got to be clear. But the system works, that??s for sure.?ÿ
I use my T2 and T3 a lot. I used to do a lot of star shots. But I get about 3? with solar, so I haven??t done much night work in the past couple of years.
Z12, Opus, and T2 solar az and ZA is quite satisfying. Not much commercial application, but it??s a great way to keep your skills sharp.?ÿ
I use my T2 and T3 a lot. I used to do a lot of star shots. But I get about 3? with solar, so I haven??t done much night work in the past couple of years.
Z12, Opus, and T2 solar az and ZA is quite satisfying. Not much commercial application, but it??s a great way to keep your skills sharp.?ÿ
That's great. When I was doing solar observations about 20 years ago, I was using a 3" total station with a solar filter and got time from a handheld GPS receiver and used ephemeris data from Jerry Wahl's website (www.cadastral.com). I seemed to be able to get consistent 15" accuracy. Getting 3" accuracy from solar observations is very impressive.
I only did a Polaris observation one time, just to say I did it, and it wasn't rigorous so I don't really know what sort of accuracy potential I might have had with it. Polaris is not an easy star to sight without a right-angle optic. I know more of the stars now, so I might pick something a little easier to see if I were to do a night observation.
I did learn how to switch the reflector for the cross-hair illumination on and off in the T2 a few nights ago. Very ingenious.
I live in the Shenandoah valley, Hagerstown MD. There are several radio towers on the mountain ridges visible all across the valley. I occupied about 45 random points well scattered throughout the valley. ZA and astro azimuth on all.
I did specifically to locate the towers sufficiently accurate to have 1 second azimuth reliability of azimuth. The towers are about 25 mi apart in a nice triangle.
I prefer tropical stars over Polaris. Vertical angles less than 30?ø.
Solar azimuth has been routinely discounted. But with Xi Eta deflection and GPS timing so easily available I don??t think solar is any less accurate than tropical stars, and 40?ø vertical to Polaris is difficult.
And often I use the Z-XII??s camera event recording for UTC, and always correct to UT1 ?ÿ
it??s been a multi year muse. Several points I have many repeat observation. In Starnet azimuth global a priori error at 3.5? returns error factor of 1.2.?ÿ
I've done Polaris at 42?ø latitude, but it's a neck bender to get the chin out of the way.?ÿ I'd hate to try it any further north without a right-angle eyepiece.
@bill93 That is why using a DKM3 (or Wild T4) is so nice, you are always looking directly into the eyepiece on the side of the instrument rather than at a steep vertical angle. Unfortunately I have neither.?ÿ
I believe polaris was used almost exclusively in the past (at least in northern latitudes) due to the fact that time was not as important especially at elongation, and it was easily found. As Larry Scott said, with accurate time and accurate ephemerides you can pretty much use any star, although you would want to avoid stars low on the horizon. BUT, I believe using a technique similar to Blacks Azimuth would be better than using a single star.?ÿ
Black's Azimuth Empire Survey Review October 1951
Dave Lehman had developed an online program to process these types of observations, but he passed away suddenly in February of 2017 and his work is no longer online.?ÿ
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