50 | | * These RINEX files can then be imported with Project > Import. |
| 51 | Precise ephemeris data can be accessed from CDDIS: |
| 52 | |
| 53 | https://urs.earthdata.nasa.gov/oauth/authorize?client_id=gDQnv1IO0j9O2xXdwS8KMQ&redirect_uri=https%3A%2F%2Fcddis.nasa.gov%2Fproxyauth&response_type=code&state=aHR0cDovL2NkZGlzLm5hc2EuZ292L2FyY2hpdmUvZ25zcy9wcm9kdWN0cy8 |
| 54 | |
| 55 | Naming convention is: |
| 56 | |
| 57 | `AAAWWWWD.sp3` |
| 58 | |
| 59 | Where AAA is the processing site, WWWW is GPS week, D is day of week in GPS week terms and the extension for precise ephemeris data is `*.sp3` (there are also orbit and clock data available here if it is needed). |
| 60 | |
| 61 | E.g `esa22234.sp3` is a precise ephemeris file produced by ESA for GPS week 2223 day 4 (Thu 18 August 2022). Note that Sun = 0 and Sat = 6. |
| 62 | |
| 63 | You can find out the GPS week here: https://www.ngs.noaa.gov/CORS/Gpscal.shtml |
| 64 | |
| 65 | Back in POSPac: |
| 66 | |
| 67 | * These RINEX files (basestation observations + ephemeris data) can then be imported with Project > Import. |