I have a dataset (in excel) of species with the coordinates in which they were sighted, collected by many different people over decades. Aside from coordinates, the dataset also specifies a datum (Nad_27, Nad_83, WGS_84). I added the data to ArcGIS.
So my fields look like:
The HorizontalDatum column is confusing me. This one excel file says the dataset is composed of 3 different datums depending on the record. Although the original datum is said to be one of those three for any given record, can I set the datum for the entire dataset to Nad_83 in arcGIS and ignore this column? Will that still be accurate? I don't understand datums or transformations enough to be sure.
If not, will I have to split the dataset into 3 shapefiles for records of each datum?
These data points are all within the same province. I just want to keep all the records in the same shapefile.
To summarize and clarify: I will need to set a geographic coordinate system for this shapefile manually, as it's coming from excel data. Can I set the entire shapefile to Nad_83, or should I split it up into 3 shapefiles, and project those with the 3 "Horizontal Datums" stated in the excel field? This would be less than ideal... I'd like to be able to query the whole dataset in one go.