Astronomic Azimuth = 232-08-04
Output from DEFLEC09
Station Name latitude longitude Xi Eta Hor_Lap
dd mm ss.sssss ddd mm ss.sssss arc-sec arc-sec arc-sec
USER LOCATION 38 36 02.00000 121 21 27.00000 -1.62 -7.05 5.63
Geodetic Azimuth = ?
Thanks.
From the DEFLEC09 ReadMe:
A positive meridian component of deflection of the vertical (Xi) indicates
that the astronomic latitude will fall to the north of the corresponding
geodetic latitude of the point.
A positive prime-vertical component of deflection of the vertical (Eta)
indicates that the astronomic longitude will fall to the east of the
corresponding geodetic longitude of the point.
The computed Laplace correction (Hor.Laplace) should be ADDED to a
clockwise astronomic azimuth, to obtain a "near-geodetic" Laplace azimuth.
Note: the deflection correction is usually negligible, yielding a
geodetic azimuth.
Note: in many textbooks, the Laplace correction is shown with the
opposite sign and is subtracted from astronomic azimuth.
In direct response to your question: I don't know. I'm too tired to try to make sense of it!
Thanks Jim.
It looks like I can add 6" to get the Geodetic Azimuth of 232-08-10, I think.
Algebraically add the convergence value at that particular point to your astronomic azimuth to get your geodetic azimuth.
Hope this helps.
Regards.
Yes, Dave, that is correct. And, to the post after this, it is not a convergence. It is caused by the fact that the direction of "up" from gravity is not the same as "up" on the ellipsoid.
Mike Craymer & NRCAN helpful hints
http://www.geod.nrcan.gc.ca/faq_e.php
Mike Craymer & NRCAN helpful hints
Lots of good stuff on his site. I've used his SPADE program for most of my Polaris sights. I wonder how many years/decades it will remain accurate enough without update.
