Calc new Long/Lat based on centroid Long/Lat

[bjcwheeler]

Hello all,
I have a centroid (center pivot) with a known Longitude/Latitude. I have a distance, in feet, away from the known center point for both Latitude(X)/Longitude(Y). I need to calculate the new Latitude/Longitude for each point so that I can create a yield map. In the example below, I need to go 1278.303527 feet to the West of 44.111834 Lat and 195 feet north of Longitude -120.102744. There are 48K records that need a new X/Y calculated. Any assistance greatly appreciated.


X Y Yield X and Y are distance from the pivot in feet.
-1278.303527 195 32.60610248 Yield is in tons per acre.
-1278.303527 175 17.17232552
-1278.303527 165 0.501224722 Pivot
-1278.303527 155 4.907260956 44.111834 LAT 44° 6' 42.6"
-1278.303527 145 4.297264892 -120.102744 LONG -120° 6' 9.88"
-1278.303527 135 1.531962682

 

[offthelip]

What earth model are you using? If you are using a spherical earth model what radius are you using?

 

[bjcwheeler]

Here is what I decided to use:
0.822256 Lat (Rad)
-2.07855 Long (Rad)

I believe I have what I need as the conversion appears to be producing points with some accuracy. Got details from here: https://gis.stackexchange.com/questions/142326/calculating-longitude-length-in-miles