If you experience a gap in your base station data or need a backup for processing, you can often rely on publicly available CORS (Continuously Operating Reference Station) data. Here's how to find and download it efficiently.
**These instructions below are specific to searching for CORS data in the United States. The workflow and data sources to check if you are working outside the United States will be different.**
Step-by-Step: How to Check for Available CORS Data
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Go to the NCN on NGS Web Map
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This interactive GIS web app lets you search for CORS stations across the U.S.
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Zoom to your survey area and identify nearby CORS stations.
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Click a station near your site
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Review the satellite systems supported (look for GPS, GLONASS, GALILEO, and BEIDOU).
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Click "More Info" under Data Availability to confirm whether data is available for your survey dates.
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Note the Site ID (e.g., CTMC) — you’ll need this to request the RINEX file.
📥 How to Download CORS RINEX Data
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Visit the User-Friendly CORS Data Page
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Input the following:
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Site ID: Use the one from the NGS Map (e.g., CTMC)
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Start Date/Time: Enter survey date and time in UTC (or adjust for your time zone)
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Duration: This is based on your survey duration
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Sampling Rate: Select 1-second interval
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Satellite Systems: Check boxes for GPS, GLONASS, GALILEO, and BEIDOU
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Click “Get CORS Data File” and wait for the download to complete
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Unzip the compressed folder to access your RINEX data for use in ROCK Desktop
✅ Things to Keep in Mind
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Not all CORS stations track all four satellite constellations.
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Some stations only record at 15–30 second intervals, which may reduce processing accuracy, or block you form processing.
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Confirm the time coverage fully overlaps with your survey flight for best results.