OPUS Projects RTN Validation - Ensuring Alignment with NSRS

1. National Geodetic Survey OPUS Projects update NOAA’s National Geodetic Survey geodesy.noaa.gov Rick Foote Rick.Foote@noaa.gov 2015 FGCS Meeting, Crystal City, VA

2. OPUS Projects RTN validation Mark Armstrong’s slide #11 showed that many RTNs are aligned with the NSRS, using the NGS RTN Guidelines for Real Time GNSS Networks document. As an example, two slides from the July 2013 RTN webinar presentation are shown next (with permission of Ken Bays, the ODOT RTN Manager)

3. Major Elements of ODOT’s Plan • Goal: Minimum of 10% of the stations in the ORGN will be NGS CORS; actually 15% of ORGN sites are NGS CORS • Process/Adjust with NGS OPUS Projects online • Process 5 days of data collected during a period of high barometric pressure over the NW United States • Fixed control in the OPUS-Projects: • NGS multi-year CORS sites that have “computed velocities” (minimum 2 ½ years data) • AND • Have long term antenna mount and location stability. • Float NGS CORS sites with “modeled velocities” • Overall Goal: compatibility with the NSRS and with existing and planned neighboring RTNs.

4. CORS Stations fixed in OPUS Projects Adjustment BREW PABH FTS5 IDPN GOBS BURN ORS2 ORK5 REDM CABL

5. OPUS Projects RTN validation From the NGS 10 Year Plan 2013-2023: Goal 3 (of 5): Expand the National Spatial Reference System Stakeholder Base through Partnerships, Education, and Outreach Objective 3-1: By 2015, provide a process for RTN operators to validate their RTNs are aligned to the NSRS and meet NGS’ acceptable standards. With RTN use expected to grow, it would be wise to engage the RTN user community in the development of a methodology for understanding how their derived coordinates are consistent with the NSRS. NGS RTN webinars: 2014:http://www.ngs.noaa.gov/corbin/class_description/RTN_Best_Practices_0314.shtml 2013: http://www.ngs.noaa.gov/corbin/class_description/RTN_Administration.shtml 2015: See http://www.ngs.noaa.gov/corbin/calendar.shtml for future webinar

6. OPUS Projects RTN validation Example: (Also CORS Station) Difference: 1.0 cm latitude 0.2 cm longitude

7. OPUS Projects RTN validation Initial NGS RTN validation may show table of C-O values Future NGS RTN validation may show daily plots of how well OPUS Projects derived positions agree with RTN manager’s positions

8. OPUS Projects Data Sharing Another idea under consideration is having user selected OPUS Projects marks ability to be integrated into OPUS Sharing Nearly 10,000 marks have been submitted to OPUS for sharing

9. OPUS Projects using Rapid Static OPUS Projects uses OPUS-S only, which requires 2+ hours of data . OPUS-RS requires 15+ minutes of data, and studies have shown that longer OPUS-RS occupations are as accurate as OPUS-S. We are considering allowing one plus hour OPUS-RS occupations in OPUS Projects

10. OPUS Projects Training OPUS Projects requires users to attend a 1 ½ day training class, usually led by State Advisors. Having hands on experience in selecting CORS, constraints, and the manner in which the network is set up is critical in the accuracy of the adjusted coordinates. However, this requires considerable expense for NGS and time commitment for the trainers and the attendees. NGS will have future discussions into the possibility of creating a web based self paced course to instruct some users.

11. Questions & Discussion 2015-04-14