| Primary satellite | Secondary satellite |
| Name | SL-4 R/B | USA 15 DEB |
| Spacetrack catalog number | 39679 | 44435 |
| Radar cross section | large | small |
| Epoch of two-line elements (UTC) | 2021 Apr 13 03:11 | 2021 Apr 12 18:11 |
| Time of closest approach (UTC) | 2021 Mar 04 11:52:06.212 |
| Minimum distance | 3565.954 km |
| Height difference | -79.509 km |
| Relative speed | 12.851 km/s |
| Angle between velocity vectors | 111° |
| Geographic position | 45.5°N, 126.6°E |
| Height | 435 km |
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