Online Positioning User Service
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What is OPUS?

The National Geodetic Survey operates the On-line Positioning User Service (OPUS) as a means to provide GPS users easier access to the National Spatial Reference System (NSRS).

OPUS allows users to submit their GPS data files to NGS, where the data will be processed to determine a position using NGS computers and software. Each data file that is submitted will be processed with respect to 3 CORS sites. The sites selected may not be the nearest to your site but are selected by distance, # of obs, site stability, etc. The position for your data will be reported back to you via email in both ITRF and NAD83 coordinates as well as UTM, USNG and State Plane Coordinates (SPC) northing and easting.

OPUS is completely automatic and requires only a minimal amount of information from the user:

1. The email address where you want the results sent
2. The data file that you want to process (which you may select using the browse feature).
3. The antenna type used to collect this data file (selected from a list of calibrated GPS antennas).
4. The height of the Antenna Reference Point (ARP) above the monument or mark that you are positioning.
5. As an option, you may also enter the state plane coordinate code if you want SPC northing and easting.
6. As an option, you may select up to 3 base stations to be used in determining your solution.

Once this information is complete, you then click the Upload button to send your data to NGS. Your results will be emailed to you, usually within a few minutes. You may upload multiple data files in a zip archive if you wish. However, be careful, the options that you choose will be applied to all of the data files in that archive (i.e. The same antenna type, ARP height will be used for all of the files in the zip file).

Please read through each of the OPUS Help Links. It is important that you understand how to correctly submit your data and how to interpret your results. An OPUS email button is provided for any inquiries or comments that you may have.

In spite of our efforts to test OPUS as thoroughly as practical, new problems will almost certainly occur. Please contact OPUS with any problems you believe you see and they will be addressed as quickly as possible.

OPUS is intended for use in the conterminous U.S. and most territories. It is NGS policy to not publish geodetic coordinates outside the U.S. without the agreement of the affected countries.
See Areas Covered.