Adding Locations to the USCities.gnd File

A few cities and locations are provided in the USCities.gnd file, usually ones that have been useful to me personally in the past.  It is highly likely that you will need to add entries to this file in order to locate a sensor at a place of interest to you.

The USCities.gnd file is a simple ascii file and can be edited with any text editor or word processor that can save files in ascii format.  The contents of the file look like this:

7 11 1991
18 40 0.0
Abq,NM
0.0  0.0 35.083 -106.60  1.0 0.0 0.0
Boston,MA
0.0  0.0 42.350  -71.06  1.0 0.0 0.0
CapeCanaveral
0.0  0.0 28.230  -80.92  1.0 0.0 0.0

The first two lines are the date and time.  These values are not relevant and are ignored for ground stations. They are there to provide file compatibility with orbiting sensors whose state vectors are given in ECR coordinates

Each entry consists of two lines.  The first line is the name of the location as it will be displayed in the browser column in the main window.  The second line contains the location in the following format

Offset time: Ignored for ground stations.  This value will always be 0.0
Altitude: The altitude of the location in meters
Latitude: The latitude of the location in decimal degrees
Longitude: The longitude of the location in decimal degrees
Speed: The next three numbers will always be 1.0, 0.0, and 0.0 for ground stations.

All numbers are in free format.  That is, they can begin in any column and have any number of white spaces between them.

Example:

Suppose we would like to add an entry for St. Louis, MO, which is located at a latitude of 38.617 degrees and a longitude of -90.193 degrees.  I don't have information about the altitude of St. Louis, so I will simply use an altitude of zero.  The entry would look like this:

St. Louis, MO
0.0  0.0  38.617  -90.193  1.0  0.0  0.0