I keep getting this error message when I wait 24 hours to to a RS session using opus. If I submit an to OPUS-RS before the 24 hour window, I don't. I'm curious why?
Warning - OPUS-RS was able to find a set of reference stations
6011 with data suitable for use with your dataset. However, your
6011 position does not fall within the polygon enclosing these reference
6011 stations. This means that the geographic interpolation algorithms
6011 performed within OPUS-RS must instead perform extrapolation.
6011 Extrapolation, especially if your position is far from the
6011 reference stations, is prone to error. Use this solution with
6011 caution.
nyci
mash
nylc
nyvh
nji2
nykt
nynb
shk5
nybr
Your station is 18.1 KM outside the polygon enclosing the reference stations
Not sure why, but I've experienced the same thing. I always have to wait until the next day to process RS solutions. I think OPUS S works the same day.
Prior to 24 hours you are most likely to get a message that not enough stations are available. You get the outside the polygon message because the you are outside the polygon, simple as that. OPUS-S & RS uses the raw XYZ position included in the header of your RINEX file. First check to see if that is correct. To avoid the message on a resubmit you can select a station that will put you inside the polygon, in the area you are working there are sufficient additional stations. OPUS-RS starts by picking the closest stations with data, you should select a station farther away that puts you inside the polygon. Being inside the polygon is a good thing because OPUS-RS uses the chosen stations to create an atmospheric correction for your observed site. Being inside the polygon gives you a much better atmospheric correction. OPUS-RS uses the selected stations and excludes your observed point and solves for an atmospheric correction at your observed point. Then OPUS-RS uses that correction and solves again with your RINEX file. This is what allows OPUS-RS to solve a position with a short amount of data.
OPUS-RS limits itself to much closer stations in order to get a good atmospheric correction. OPUS-RS can use stations much farther away because it uses the long observation time to solve for atmospheric correction.
In addition OPUS-RS uses more observables L1, P1/C1, L2, P2/C2, while OPUS-S uses only L1 & L2. Sometimes CORS station RINEX files require cleaning up of the extra data. This is not done immediately because NGS knows that there are users that want answers as soon as the data is received by NGS. I would surmise that the data cleanup occurs when the NGS computers are less busy.
If you are going to do a lot of OPUS-RS get in the habit of requesting extended data. You may find there are some stations that always give you bigger residuals. You would want to exclude those stations unless it is absolutely necessary to get a solution. Sometimes a 7 CORS OPUS-RS can be better than a 9 CORS OPUS-RS.
Paul in PA
nyci
mash
nylc
nyvh
nji2
nykt
nynb
shk5
nybr
Joe,
All of these stations are to the north, west and south of you. For some reason OPUS is not selecting any Connecticut CORS which would fill in to the east.
Like Paul said it's my understanding that OPUS chooses the 9 closest CORS with data. What happens when you resubmit in 48 hours and 72 hours? Maybe the Connecticut CORS are a little slow uploading to NGS.
The best solution may be to manually select the CORS you want OPUS to use to give you the best geometry and data quality.
