www.gov/OPUS/ngs.noaa.about
The National Geodetic Survey (NGS) - USA has enhanced its popular
Online Positioning User Service (OPUS) to improve positioning
results for GPS field projects consisting of multiple survey locations. The new project option, called “OPUSProjects,” allows
This Online Positioning User Service provides simple access to high-accuracy National Spatial Reference System (NSRS) coordinates. Upload a data file collected with a survey-grade GPS receiver and obtain an NSRS position via email.
OPUS requires minimal user input and uses software which computes coordinates for NGS' Continuously Operating Reference Station (CORS) network. The resulting positions are accurate and consistent with other NSRS users.
Your solution is sent privately via email, and, if you choose, can also be shared publicly via the NGS website..
Accuracy
Under normal conditions, most positions can be resolved to within a few centimeters. Estimating the accuracy for a specific solution is difficult, however, as formal error propagation is notoriously optimistic for GPS reductions. Systematic errors, such as misidentification of antenna or height, are not detected. Local multipath or adverse atmospheric conditions may also negatively impact your solution