Hi,
I've looked in an online manual and also googled but can't find anything on the Reference Refractive Index for a Topcon GPT 7500. One online source says 0.14 but the software I'm using says it must be between 1.0002 and 1.0004. Anyone able to help?
Thanks.
ss
What software are you using? Mine says K=0.14 or 0.2 coefficient of refraction.
Apples and oranges!
see:
http://en.wikipedia.org/wiki/Refractive_index
for an explanation of "refractive index."
Loyal
You are talking about 2 different things. If you look in the Topcon manual, you should find an explanation of each.
The Atmospheric Correction is a number between about 1.000200 to 1.000400 and is affected primarily by the atmospheric temperature and pressure. It is basically a comparison between the speed of light in a vacuum and in the air through which the measuring beam passes. We can either enter the correction directly into the instrument from a table or enter the temp and press and let the instrument calculate it. I believe the numbers which are entered is the deviation from "standard" temp and press of 59°F and 29.9" Hg. At least with the Topcons.
The Coefficient of Refraction, "K", you cite of 0.14 or 0.20 is used in the calculation of the Atmospheric refraction correcting term. The correction is dependent on the angle at the center of the earth between your instrument and the prism and affects both the distance and elevation calculation. Topcon provides no explanation in their manual for the use of either value, 0.14 or 0.20
Well said Tyler. I misunderstood the original post and was searching for a simple answer....duh on my part. Thought he was using a software that....ahh never mind...
Wendell...please remove my dumb post (I thought I was banned for a few days....:).....)
