I'm preparing to do some "Azimuth by direct Solar Observation", and in my reading, I'm finding that the "older school" Davis Foote and Kelly seemed to spend a lot of time on the Altitude method, while Ghilani and Wolf (as well as a short document written by John Sands, PLS for Caltrans), favor the Hour Angle method.
I'm planning on using the latter, but wonder if the more recent (by Old Timers' standards) method is favored, because of better time keeping availability than in the 50's and 60's, i.e. using an iPhone or equivalent for the time keeping. I'm not clear on how available the radio signals were then (WWV, CHU, etc.). But even if they were available in the field they couldn't have been that convenient to use. Just curious.
Hour Angle method will yield accuracy...easier...due to our ability to have precise timekeeping.
Our equipment dealer even sold the ephemeris books, which contained the program you could enter into your calculator. I still have some in a drawer somewhere, valuable mostly as a curio item, as the tables must be updated for every year.
I was cranking these out on my old hp48 up until about 1995 or so.
You can still obtain epemerides from a gentleman named Jerry Wahl. at http://www.cadastral.com/2016ephs.htm
John Evers, post: 356070, member: 467 wrote: Hour Angle method will yield accuracy...easier...due to our ability to have precise timekeeping.
Our equipment dealer even sold the ephemeris books, which contained the program you could enter into your calculator. I still have some in a drawer somewhere, valuable mostly as a curio item, as the tables must be updated for every year.
I was cranking these out on my old hp48 up until about 1995 or so.
You can still obtain epemerides from a gentleman named Jerry Wahl. at http://www.cadastral.com/2016ephs.htm
Mr. Wahl was kind enough to assist me with his very cool spreadsheet for Polaris. And I've recently checked out his recently updated ephemerides too.
i purchased MICA now, which has everything I need for the sun (and just about every other celestial body you've ever heard of).
As a matter of procedure, did you simply take multiple readings, direct and reverse, noting the time precisely, then reduce all the numbers later? Or did you do the math in the field with the HP?
rfc, post: 356073, member: 8882 wrote: Mr. Wahl was kind enough to assist me with his very cool spreadsheet for Polaris. And I've recently checked out his recently updated ephemerides too.
i purchased MICA now, which has everything I need for the sun (and just about every other celestial body you've ever heard of).As a matter of procedure, did you simply take multiple readings, direct and reverse, noting the time precisely, then reduce all the numbers later? Or did you do the math in the field with the HP?
I put together a procedure I used when I made my observations for someone that asked essentially the same question as you. I also included a copy of my field book data pertaining to how I set it up for making the observations.
Send me your E-Mail address and I'll forward it all to you.
Just remember you only get two chances to look directly at the sun through a transit.
Once with each eye.
rfc, post: 356073, member: 8882 wrote: Mr. Wahl was kind enough to assist me with his very cool spreadsheet for Polaris. And I've recently checked out his recently updated ephemerides too.
i purchased MICA now, which has everything I need for the sun (and just about every other celestial body you've ever heard of).As a matter of procedure, did you simply take multiple readings, direct and reverse, noting the time precisely, then reduce all the numbers later? Or did you do the math in the field with the HP?
We did the math in the field, and then ran our traverse.
Charles L. Dowdell, post: 356080, member: 82 wrote: I put together a procedure I used when I made my observations for someone that asked essentially the same question as you. I also included a copy of my field book data pertaining to how I set it up for making the observations.
Send me your E-Mail address and I'll forward it all to you.
Thank you very much. I started a "conversation".
The only reason to do the altitude method is if you don't have accurate time. The results are degraded by the uncertainty in the refraction correction.
rfc, post: 356066, member: 8882 wrote: I'm preparing to do some "Azimuth by direct Solar Observation", and in my reading, I'm finding that the "older school" Davis Foote and Kelly seemed to spend a lot of time on the Altitude method, while Ghilani and Wolf (as well as a short document written by John Sands, PLS for Caltrans), favor the Hour Angle method.
I'm planning on using the latter, but wonder if the more recent (by Old Timers' standards) method is favored, because of better time keeping availability than in the 50's and 60's, i.e. using an iPhone or equivalent for the time keeping. I'm not clear on how available the radio signals were then (WWV, CHU, etc.). But even if they were available in the field they couldn't have been that convenient to use. Just curious.
Radio Shack (Realistic) sold a small 9v WWV radio in the 70s at an affordable cost. It was called the Time Kube. Soon a 800 # to Fort Collins was available to access time.
41 cv with time module or 41 cx facilitated calcs and time marking.
Surveyors who were performing Polaris observation could now get added sleep.
rfc, post: 356066, member: 8882 wrote: I'm preparing to do some "Azimuth by direct Solar Observation", and in my reading, I'm finding that the "older school" Davis Foote and Kelly seemed to spend a lot of time on the Altitude method, while Ghilani and Wolf (as well as a short document written by John Sands, PLS for Caltrans), favor the Hour Angle method.
I'm planning on using the latter, but wonder if the more recent (by Old Timers' standards) method is favored, because of better time keeping availability than in the 50's and 60's, i.e. using an iPhone or equivalent for the time keeping. I'm not clear on how available the radio signals were then (WWV, CHU, etc.). But even if they were available in the field they couldn't have been that convenient to use. Just curious.
If I recall, In Ted Madsen's book Mathematics for Land Surveying he had a fill in the blank form for Solar and Polaris observations. I remember using the one for Polaris but not the one for Solar. This was back in the late seventy's when I took his course
easiest way for me to get accurate time was to use an actual shortwave receiver to get WWV and to chase the trailing edge with the tangent screws until the instant of the 0:01 "click" and then read the instrument.
If all the observations are at a "known" time and a known interval it's easier to spot the blunders or the outliers.
The sun moves 15 minutes of angle per minute of time, so if you have 6 or 8 shots on the minute, integer minutes apart, you have yet another check on your work.
rfc, post: 356109, member: 8882 wrote: Thank you very much. I started a "conversation".
There is a free ware Solar program called "Spade" that works pretty well for solving the the observation reductions. It's not as good as the one from the Lietz Ephemeris that was for the HP 71B that I had my youngest boy convert over to my HP 75C that I like better for the reductions.
The way I always did mine was by setting my HP 41cx to the wwv radio signal and assigning a key to freeze the display on the time. I would have the calculator in my left hand while I place the crosshair slightly in front of the sun's edge. As the edge of the sun caught up with crosshair I would hit the button on my calculator freezing the time. Read and record the angle, read and record the time, repeat. I did two shots leading edge, two shots trailing edge, invert and repeat. 8 shots total.
The problem I have with the Navy Clock App is about 1 second delay that (I think) is caused by the digital delay in the cell phone systems or the internet.
With the WWV you can also get the DUT to correct to UT1 time. Oddly, I was checking my Radio Shack Timekube and the extra ticks were not there. It's been so long since I have done a sunshot I thought they may have changed.
According to this website
http://maia.usno.navy.mil/ser7/ser7.dat
DUT is currently at zero.
28 January 2016 Vol. XXIX No. 004
______________________________________________________________________
GENERAL INFORMATION:
To receive this information electronically, contact:
ser7@maia.usno.navy.mil or use
<"> http://maia.usno.navy.mil/docrequest.html>
MJD = Julian Date - 2 400 000.5 days
UT2-UT1 = 0.022 sin(2*pi*T) - 0.012 cos(2*pi*T)
- 0.006 sin(4*pi*T) + 0.007 cos(4*pi*T)
where pi = 3.14159265... and T is the date in Besselian years.
TT = TAI + 32.184 seconds
DUT1= (UT1-UTC) transmitted with time signals
= +0.1 seconds beginning 26 Nov 2015 at 0000 UTC
= +0.0 seconds beginning 31 Jan 2016 at 0000 UTC
Beginning 1 July 2015:
TAI-UTC = 36.000 000 seconds
Well, this may be a dumb question, but does one use a DC for this? That is, if the DC can be set to read Azimuth Only (I think I asked this question in the context of SurvCE sometime ago...I'll look for the thread). The advantage I see in using a DC is that it would record the data. If I'm not mistaken, SurvCe can time stamp the readings too. Problems doing it this way?
