Assign coordinate system

Discussion created by alexbernhard on Jan 26, 2012
Latest reply on Jan 27, 2012 by alexbernhard

I am a biologist just starting with GIS, hence my question might be a bit simple.
As we process a big lot of .asc files I am writing a series of scripts. I get the .asc files without any spacial reference, but I know the correct coordnate system. Now, the .asc files undergo the following steps:
- Conversion to Raster data
- Reclassification
- Conversion Raster To Polygon
- A Projected coordinate system is assigned
- The area of the polygons is calculated

If I import the various outcome to ArcMap, the result shows a very much too small area. It seems that the data in degree, is interpred as data in Meters. Which makes perfectly sense but is obviously wrong. My question is, when (and how in my Python scripts) do I have to assign the geographic coordinate system and which method do I have to use to assign the projected one? For the latter I currently use Project_management.

Best regards and many thanks