| Primary satellite | Secondary satellite |
| Name | Cosmos 1603 | IRS-1A Rocket |
| Spacetrack catalog number | 15333 | 18961 |
| Radar cross section | large | large |
| Epoch of two-line elements (UTC) | 2026 Jan 13 09:55 | 2026 Jan 13 15:59 |
| Time of closest approach (UTC) | 2025 Dec 14 13:27:44.214 |
| Minimum distance | 65.594 km |
| Height difference | 0.006 km |
| Relative speed | 5.231 km/s |
| Angle between velocity vectors | 41° |
| Geographic position | 47.0°S, 127.8°E |
| Height | 871 km |
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