How to populate lat and long coordinates in data table when creating new points?

[AdrianDown]

Hello.  Here's the problem I'm trying to solve.  I want to estimate the depth to a geologic formation based on 1) a set of measurements from various drill holes and 2) a surface geologic map.  The wrinkle is that there are faults in the area where the depth to the geologic formation changes discontinuously.

Here's what I've done so far.  All of my drill hole depth numbers are in an Excel sheet as decimal degrees.  The sheet has only three columns: latitude, longitude, and depth.  I've been able to import the geologic maps, georeference them, and map them along with my depth numbers.  All of the interpolation methods that I've used have been inaccurate, I think because I need to add more data points to the depth measurements to improve the interpolation, especially around areas where the depth changes discontinuously, like along faults.

Here's the problem I'm having.  I want to find a way to add new data points to my depth data set quickly.  I can use the editor to create new points in the "well depth" layer, but when new points are created, the latitude and longitude fields of these new points in the attribute table just take on whatever value I set them to in the point creation template.  In other words, ArcMap doesn't populate the lat and long fields in my data table, which I used to georeference my depth points initially, when I create new points.  Hence, all the added points have lat and long fields in the attribute table of "0,0", or whatever else I set as the default.

My questions are:
1) Is there a way to get ArcMap to populate the lat and long fields of my attribute table with the position of the points that I create?
2) Alternatively, should I just forge ahead and create these points, even though the lat and long fields are wrong?  Maybe all I need for interpolation is the depth attribute, which I can set manually?  The problem I foresee with this approach is that I won't be able to export a CSV or other form of the depth points once I modify them in ArcMap.
3) Should I be creating these new points on a separate shapefile?  If so, should I have a "lat", "long", and "depth" field for these new points, as I do for my original data set?  I have tried using a new empty shapefile to hold my new points, but I haven't been able to change the names of the fields in the attribute table from the default "id" to my desired attribute names.  I'm also worried that trying to interpolate from data on two separate layers, or having to merge two point layers in the future, will be a major headache.

Any advice is appreciated.  My ArcGIS knowledge is limited, so I feel like I'm fumbling around in the dark here.  Thanks!

[ScottMoyer · Accepted solution]

After points are edited in (multiple to save time) you can right click one of the fields lat or long, go to 'Calculate Geometry...', and there is a selection in 'Units' for decimal degrees. Calculate that and then do the other field. I've never done this but one of the first things I would check is that existing coordinates aren't altered; they shouldn't be.
I can't help you with the accuracy of the interpolated points.
Scott

[AdrianDown]

The "Calculate Geometry" option was perfect, exactly what I needed.  Thanks so much!!