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New California Datum (March 2018)

04-03-2018 03:15 PM
New Contributor III

Does anyone out there know if or when the new California RTK base station "CSRS Epoch 2017.50 (NAD83)" coordinate system (and datum) will be available in ArcGIS Collector?  It went live with the CSRS base stations on March 1st, 2018.  See more information here:  Scripps Orbit and Permanent Array Center (SOPAC) 

Matt S.

12 Replies
MVP Frequent Contributor

CRTN Community Notice

The CSRC migrated CRTN coordinates to CSRS Epoch 2017.50 (NAD83) this evening at 2018-03-01 4:00 UTC.  Please also visit and click the epoch link. 

Esri Notable Contributor

Hi Bill and Matt, 

I'm not sure this needs a separate geographic coordinate system definition, but could be covered by allowing data to be tagged with the 2017.5 epoch date. I have entered an internal issue and will discuss it with Kevin M. Kelly.

At least, that's my current thinking based on these statements here:

 It is rigorously aligned to the current definition of the National Spatial Reference System (NSRS) through a set of coordinate transformations from ITRF2014 to NAD83(2011), published by the NOAA/NOS National Geodetic Survey (NGS).

CSRS Epoch 2017.50(NAD83) replaces the previous “CSRS Epoch 2011.00 ITRF2005 NAD83(NSRS2007)” datum that included coordinates for 830 CSRN stations.

Geoid heights from the latest NGS-published model, GEOID12B, have been applied to develop Derived California Orthometric Heights for all of the CSRN stations, in accordance with PRC §§8890-8902.


New Contributor III

Thank you Melita, anything you can do to have that epoch show up in ArcGIS Collector and other ESRI applications would be great!


New Contributor II


Is there any news on getting the epoch 2017.5 into Collector?  I am struggling with aligning my data using Collector and CRTN.  I walked up up to the CRTN control point that I was connected to in RTK , collected data using Collector app and recommended profile, app said I was 15cm accurate, then I plotted results in ArcMap and I was really 1.25m away from the control point.  There is no way currently to get accurate data in Collector using the CRTN epoch 2017.5.  I would really appreciate this being addressed in the next Collector update. 

FYI the EOS Tools Pro GPS app reported location correctly, but Collector did not.  Using an Arrow 100 GPS, but will be going to Arrow Gold soon, so I need to get this resolved before collecting cm level data with Collector and CRTN RTK data.

New Contributor III

Hello Mike,

While Collector implements support for this new datum (and possibly epochs in the future (but don't quote me on this)), there is a way to fool the “system” with Arrow and the Datum shift feature we have in Eos Tools Pro. 

When connected to your RTK base/network which is referenced to the Nad83 2017.5 datum, the output coordinates of the Arrow will also be in this same datum. This is the reason why Eos Tools Pro is showing you the right coordinates.

At the end, what Collector is expecting from the Arrow is Nad83 2011, and then it goes through the existing on-the-fly datum transformation feature of Collector to match the map in web mercator (which should be WGS84 G1762, and which is ITRF epoch 2005), if you followed the video tutorial on our web site. 

Therefore, using the datum shift feature of Eos Tools Pro (Config menu), you can make the Arrow output in Nad83 2011 and keep the actual config of Collector unchanged. Here is what to do:

1) get a point (any point) in the aera where you'll be working, for which you have coordinates expressed in both Nad83 2011 and 2017.5. 

2) convert lat/lon to decimal degrees and keep elevations in meters

3) in Config menu in Eos Tools Pro, activate the offset switch on the top. Enter the "from” and “to” coordinates (this will soon change in the next release to “datum shift”, to avoid confusion with the new laser offset feature we introduced at the UC this year). You want the “from” to be the 2017.5 coordinates set and the “to” to be the 2011 coordinates. Then click on “calculate offset” and save to the receiver. 

If you do not have, nor cannot get a sample point from the State authorities who defined this datum, do not panic. 🙂 . Go to the HTDP web site and get a set of coordinates yourself. Here's how:

1) follow the procedure in this document (still from our learning center menu): with the following difference:

2) you will need to select input datum to be NAD83 epoch 2010.0 (not 2011.0) and output Nad83 datum to have epoch 2017.5

this way you'll get your pair of coordinates. 

Collector should love this output from the Arrow better :-). Once the Collector team implements support for this new Californian datum, I suggest you disable the above and let Collector handle it. At least you have a solution now. 

I have assumed you are using iOS. The same is available in Eos Tools Pro for Android, under the Settings menu.

Any issue, please write to us at

Good luck,


Eos Positioning Systems

New Contributor III

Hi Jean, Mike,

I tried using the offset but didn't have much luck with it.  I got around this issue by creating my own basemap for ArcGIS Online.  This basemap is in original NAD83 not the Web Mercator coordinate system that the ArcGIS Online basemaps use (all my GIS data is in the original NAD83).  I use a feature service that is hosted on my cloud server through ArcGIS Enterprise (Server) to put my data into.  This feature service is in the orignial NAD83 as well.  This way, there are no datum changes/shifts between ArcGIS Online and my final product.  I know this isn't a perfect solution but it's working pretty well so far.  I worked with Jean and Art Andrew at Orange County Public Works.  It was a bit of a struggle but finally Art suggested that I don't do any datum shifts at all.  That's how I got the idea to do what I'm doing.  

Jean, if you could help me get the Datum shift numbers for going from the original NAD83 to the NAD83 2017.5 that I think would be the perfect solution for me and maybe for Mike or others.  If you have any other ideas that would be great to.  I'm open to suggestions.

FYI, I'm in CA State Plane Zone 2.



City of Healdsburg

New Contributor III

Hello Matt,

The big problem in your case is that you are using NAD83 (Original) (1986). To my knowledge, NGS does not have/publish any transformation parameters nor a grid file that would let you transform to/from NAD83 2011 (or 2017.5) from/to NAD83 Original. 

The best in your case would be to occupy/find a monunent for which you have NAD83 Original coordinates and NAD83 2017.5 coordinates. This way you would be able to compute the shift that is needed. If you find such a monument, please email the coordinates at and we will help you compute the local shift that you can use in Eos Tools Pro. If you can find few of these in your aera of work, that would even be better. 

Let me know.


Eos Positioning Systems

New Contributor II


Thank you very much for the quick reply!  I appreciate the assistance, will give this offset a try.

Mike Bonk

New Contributor III

I am still pretty new to the GNSS and RTK stuff--what XY Coordinate system are you all using in ArcGIS for the CSRS Epoch 2017.50 (NAD83). I am in the same boat here.... EOS Arrow Gold, CRTN RTK, ArcGIS Collector, ArcGIS. Right now I am just looking for the proper coordinate system for a feature class in ArcGIS and for my GCPs in Pix4D.  Hoping that ESRI supports this coordinate system soon and appreciate EOS's response above on one workaround for the datum shift.

Michael Loconte