capture a simple GPS reading on June 21st should be easy for any professional land surveyor. You could choose a location near your home or office, some known control point in your geographic area or even at the jobsite you happen to be working at noon. There are millions of control points around planet earth to choose from. Take a look at some of the terrific photos submitted by land surveyors to Land Surveyors United, showcasing benchmarks, markers and control points in virtually every place on the planet. Here is an interesting album from the site which pulls hundreds of these submissions together into one place.