v2024.06.01 AWS

NGS OPUS Failure Notes

Quick Links

[ Bad File, Zero Length, Unrecognized File ]

[ other OPUS processing failures ]

[ Submitting a file to iGage for help ]

[ is CORS data available yet? ]

File Errors

If the returned OPUS error message is something like 'bad file', 'zero length file' or 'unrecognized file':

These errors are usually caused by an aggressive anti-virus tool holding the intermediate observation files hostage while they are checked for viruses as iGx Download attempts to compress them to a ZIP file for submission.

You can troubleshoot this by setting the iGx Download tool to 'Normal' mode on the Configuration tab:

Then when you submit, additional information about the submitted file will be shown. Check the resulting OBS Size:

If the OBS Size is 0 (zero) then your antivirus has probably interfered with the conversion.

Sometimes, resubmitting the job will work (because virus detection has completed). If not, contact us.

Help! My OPUS submission fails or is noisy

You have collected a static observation file and submitted it to OPUS-RS (Rapid Static) or OPUS-STATIC and the job returns with a message that your file is noisy or one of many other possible error messages.

Step #1 Just wait

The most common issue is there is no nearby CORS data available to process your job against... yet:

If you wait until midnight UTC plus 8 to 12-hours the nearby stations will probably post their observation data, then if you resubmit your file it may process successfully as the baselines are much shorter.

Because the NGS CORS collection process from stations is not always successful, manual intervention by the NGS is sometimes required to 'ingest' the missing data. When this happens, you may need to wait an extra day or two for the NGS to complete file collection and their QC operations! Obviously, this is outside of your or our control.

You can troubleshoot/predict data availability as shown in this FAQ [ Is CORS data available? ] below.

While you are waiting, consider reading the FAQ (Step#2 below) starting on page 43.

Step #2 Read the FAQ

Before you call iGage to complain about your failed job, please read this FAQ

[ Best OPUS Practices for New and Experienced Users ]

beginning on page 43 of the linked PDF document.

Assuming you collected your observation in a location with clear sky (see page 54 through 60) then most of the time your problem will be there is no nearby CORS data available yet.

You can read about this issue:

#1 page 43: OPUS RS is dicey

#3 page 44: Availability of CORS

#4 and #5 page 46: Hourly vs. Daily data availability

Sometimes the issue is:

#6 page 49: Offline CORS Stations

#7 NGS CORS Station Quality

The issue rarely (perhaps never) is a bad receiver.

WAIT, then


Step #3 Wait

If you are using an iGage receiver, we (iGage) can and will help you. However, we would appreciate it if you wait a reasonable time period, then resubmit your job to see if it still fails; before you contact us:

Wait until midnight (UTC) following the end of your occupation, then wait 1-day plus 12-hours, then resubmit. See [ Time Examples ]

If the job still fails and you would like us to help, continue to the next Step #4.

Submit your observation file to iGage support with the iGx Download Send Button

Step #4  Send your job to iGage for assistance

Using the iGx Download tool: highlight / select the observation in the observation list:

Then click the Send button:

Confirm that you want to send the file to iGage:

Wait for the entire job file set to compress. this could take a while (a few minutes), the progress for each file will be displayed on the program's bottom status line.

Wait for the compressed file to upload: the compressed the file is huge and it will take a while (again, a few minutes, depending on the speed of your internet connection):

when the file upload completes a message will be displayed. YOU MUST TELL US THE NAME OF THE FILE and that it is available:

You can now request that we look at your observation.


We won't look at any failed OPUS-RS jobs sooner than the 'following midnight UTC + 1-day + 12-hours' after the end of your observation.

We can't help you until nearby, matching CORS data is available at the NGS RINEX repository.

We can not control the NGS collection period or delays. It is a complete waste of our time to look at your file until after nearby, overlapping CORS data is available.

Read the [ Is CORS data available ] section for detailed information on how to debug CORS data availability.

Time Examples:

  How long do I need to wait before resubmitting and asking for help?

Before asking for help from iGage, please wait for all possible nearby CORS to become available, then resubmit your observation. If it still fails, then you can share your job with us using the method shown in Step #4 above, then we can help you figure out what is up.

We understand that sometimes your jobs process immediately after you collect them. But since you are getting a failure and no nearby CORS data is the problem 99.5% of the time, we appreciate your waiting a suitable time before contacting us for help.

The [ Is CORS data available ] section of this document shows the large variability in the posting time for a reliable station. If your job depends on an unreliable station, then on a particular day you may need to wait a really long time.

OPUS Minimum Wait Time

Waiting until 'midnight UTC + 1-day plus 12-hours' following the end of your observation should generally be long enough.


Observation ended at 4:54 pm on Monday the 19th of December MST (Mountain-Standard-Time).

Convert the ending time to UTC: Monday December 19 23:54 UTC

The following midnight is 6-minutes later, Tuesday December 20 at 00:00.

Add 1-day plus 12-hours (that is 36-hours): 12:00 Wednesday December 21 UTC.

Convert to Mountain Standard Time: Wednesday December 21 5:00 am MST.

If the observation file had lasted 7 minutes longer, it would have extended 1-minute into December 20th UTC and you would have to wait an additional 24-hours, until Thursday December 22 at 5:00 am MST.

If this happens and the overlap is a short insignificant period, consider trimming the overlap (just throw it away) using the Trim function in the iGx Download tool.

Is CORS data available?

You can use the NGS 'Data Availabilty Plot' to see if there is something wrong with the ingestion of data from the CORS station to the NGS repository.

For an example, assume that we collected 4-hours of data near Wendover Nevada on Saturday January 14, 2023 starting at 17:00 UTC and ending at 21:00 UTC.

Note: time zones and daylight savings make GPS time and date telling very difficult.

In the example at hand, while Nevada is UTC - 8 hours, Wendover Nevada is in a time zone cutout on Utah time (UTC - 7); additionally the annual conversion from Mountain Standard Time (UTC - 7) to Mountain Daylight Savings Time (UTC - 6) adds even more confusion.

The iGx Download tool can help. On the configuration tab there is a 'Show UTC Time' checkbox:

When dealing with questions of CORS observation overlap, it will always be easier to check this box and let your computer do the time zone conversions, fully working in UTC instead of your local time zone.

Browse to the NGS CORS Map ( https://geodesy.noaa.gov/CORS_Map/ ) and zoom into the station you want to inspect:, click on the station that you are interested in:

In this case, P113 is a nearby, very reliable UNAVCO PBO station. Click on 'Get Site Info' link and a new tab will open in your browser showing station details for P113:

Click on 'Data Availability' and the 'Data Availability Profile' for the selected station will be shown.

To convert the current day to a Julian count, click on the 'GPS Start Date' entry box:

The current month will be shown with the calendar day-of-month and the Julian day-of-year. The Julian date (which is the 1-based incremental day of the year) Saturday was Julian day 14.

Now, click outside of the calendar to return to the availability timeline. Look at Julian day 14:

You can see that day 14 is light-gray (not Blue) and there is currently no data available for the P113 station, we will need to wait longer for P113 station data overlapping our job to become available.

Predicting NGS CORS Data Collection Time

You may be able to predict the time of the future collection by looking at the collection time of the previous day(s).

Go to the NGS HTTPS CORS data bucket:


The root bucket will be shown:

Click on rinex, then the year (2023), then the previous Julian day (13), then the station (p113):

The observation data (xxxx.23o.xx) was available for use at 5:59 UTC on the following day, December 14th.

Checking Julian day 12:
the availability time again was 5:59.

Checking Julian day 11:
the availability time was 18:23. This is 12-hours after we might have expected it to become available.

Summarizing three weeks of availability data for P113:

This is a good, RELIABLE station. But sometimes you will need to wait an extra day for data to become available.

There are a few CORS stations that are somewhat unreliable:

And others are worthless:

If you use OPUS regularly, you will soon develop a list of unreliable stations and you can list them in the 'Exclude' box of the OPUS submission form.

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