How to create arbitrary coordinate system in ArcGIS Pro?

[AlyssaPietraszek1]

I need to georeference a jpeg map of an archaeological excavation with an arbitrary grid system where each square in the grid is 1 m x 1 m. The locations of artifacts within the grid are listed according to Northing and Easting decimal locations relative to a false origin 0,0 and the distance north and east from the origin point in meters. For example, an artifact located 1.5 m north and 2 m east of the origin point is at 1.5 N, 2 E. 

How can I create such an arbitrary coordinate system in ArcGIS Pro in order to produce a map of the artifact locations across the excavation grid?

I have never really used ArcGIS before so I'm not sure where to start.

Thank you!

[DavidPike]

Great question, after some research I came across this:

Local Cartesian Projection—Help | ArcGIS for Desktop 

https://pro.arcgis.com/en/pro-app/help/mapping/properties/local.htm 

[BojanŠavrič]

Go to Map Properties, select "Coordinate Systems" and then "New Projected Coordinate System..."

Local projection would work for your application. For Longitude and Latitude of Center use geographic coordinates of the origin point, False Easting, False Northing, and Azimuth are 0, and Scale Factor mark as 1. For the Geographic Coordinate System, select the one of your origin point.