[alma-config]UTM coordinates, etc.

[Simon Radford]

Mark,

You are entirely correct, as usual! The exact coordinate transform from UTM to astronomical latitude and longitude is very messy, but tractable. In practice, of course, we'll end up determining precise antenna locations after the fact by measuring the
baselines with astronomical observations.

For civil engineering, road layout, etc. the UTM coordinates are the only game in town. Any discussion of any other system will simply confuse the issue. So it's up to us to get the coordinates right.

Simon

For the curious, DMA TM 8358.1 states:

- The UTM system divides the earh into 60 strips, each 6 deg wide, centered at +- 3 deg, +- 9 deg, etc., longitude.

- For each strip, the ellipsoidal Earth is projected onto an elliptical cylinder that is secant to the ellipsoid and intersects the ellipsoid +- 180 km from the central meridian.

- The central meridian is given the coordinate value 500 km E.

- Different reference ellipsoids are used with different map datums.