Posted by jdehan
I have a base line established in state plane coordinates. I set up at one end backsight the other end and turned an angle to magnetic north. I obtained the declination for the date of observation and added it to the angle to obtain true north. I am approximately 15 degrees different than an observation made years ago. The change in declination over these years would not amount to 15 degrees. What am i not seeing here? If anyone has done this procedure please help.I looked at a USGS quad map and the old angle is close to the angle obtained from measuring on the map.
To read the rest of this thread, go to
True North from Magnetic North
October 13, 2010