I have an excel spreadsheet with lat and lon columns, and 5 additional columns with associated data. I want to open the data points in ArcMap 10.2. I was told that the data was:

based on a Lambert conformal projection with the following specifications:

Central latitude/longitude 40N, 97W

First secant angle 33N Second secant angle 45N

Origin at -1872000.0, 828000.0 from center.

How do I open this data in Arcmap with the correct spatial reference system?

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    You say lat and lon columns. Are there lat/lon values in those columns or are they projected using the ProjCRS defn? What's the GeoCRS aka datum? NAD83? – mkennedy Jan 8 '15 at 18:46
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    If you have latitude and longitude, then points generated are NOT in Lambert. If you can define what they are then getting to what you want them to be is easy. Just remember that latitude is Y (if you think "lon and lat", it helps keep things straight). – Vince Jan 8 '15 at 18:47

After making some assumptions, here's a possible prj file for the definition that you gave. The assumptions are:

  1. GeoCRS is NAD 1983
  2. False easting is 1872000.0 meters (assuming the origin values are given in meters)
  3. False northing is -828000.0 meters (this is the one that I feel most unsure about)

(2) and (3) are based on the statement that the 0,0 coordinates are -1872000, 828000. That means the center point of the projection has the opposite sign values. That is, +1872000.0, -828000.0.


Copy out the PROJCS[...]] string and put it into a text file as a single line with a carriage return at the end. Change file's extension to .prj. You can now use the import option to assign it to the data or the data frame.

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