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LES
 LES
(@les)
5+ posts Member
Joined: 6 years ago
Posts: 8
February 6, 2019 8:01 am  

My ?0.02 is that every practicing surveyor should have as a resource the following book:  A Manual on Astronomic and Grid Azimuth by R. B. Buckner, Ph. D.  It is a well written and practical book.  I have used it as a reference many times.


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Bill93
(@bill93)
5,000+ posts Member
Joined: 9 years ago
Posts: 5158
February 6, 2019 9:42 am  
Posted by: Norman Oklahoma
And when you do a sunshot what datum is the orientation relative to? '83? '27? Something else?

Astronomical north, which is geodetic north on either NAD to better than your likely measurement accuracy.

Accuracy is limited by how well you can time it with one method and by vertical refraction in the other method.


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GeeOddMike
(@geeoddmike)
500+ posts Member
Joined: 8 years ago
Posts: 906
February 7, 2019 12:34 pm  

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

  

“To be surprised, to wonder, is to begin to understand,” - Ortega y Gasset


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