| Primary satellite | Secondary satellite |
| Name | Courier 1B Rocket | Kosmos-1821 |
| Spacetrack catalog number | 59 | 17525 |
| Radar cross section | large | large |
| Epoch of two-line elements (UTC) | 2025 Dec 12 04:47 | 2025 Dec 12 06:31 |
| Time of closest approach (UTC) | 2025 Nov 14 18:08:26.309 |
| Minimum distance | 1.020 km |
| Height difference | -0.590 km |
| Relative speed | 12.215 km/s |
| Angle between velocity vectors | 111° |
| Geographic position | 0.9°N, 179.1°W |
| Height | 961 km |
|