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• Name(s): Top 25 by Time of Closest Approach
• Order by Time of Closest Approach
• Return first 25 items

Data current as of 2025 Apr 21 08:07:44 UTC

Computation Interval: Start = 2025 Apr 21 08:00:00 UTC, Stop = 2025 Apr 28 08:00:00 UTC
Computation Threshold: 5.0 km
Considering: 11,303 Primaries, 27,288 Secondaries (80,179 Conjunctions)
12 SGP4 Propagation Errors
Computation run time: 06h 07m 22.833s

• Data: The GP Data button links to a page which provides the GP data used to generate the associated prediction.
• NORAD Catalog Number: NORAD Catalog Numbers of the two conjuncting objects.
• Name: SATCAT names of the two conjuncting objects. Operational status of each object is shown in brackets, using the standard CelesTrak SATCAT codes.
• Days Since Epoch: The number of days from the epoch of the NORAD GP or SupGP (green) element set used to produce the prediction until the time of closest approach for the conjunction.
• TCA (UTC): Time of closest approach.
• Min Range (km): The distance between the two conjuncting objects at the time of closest approach.
• Relative Speed (km/sec): Relative speed of the two conjuncting objects at the time of closest approach.
• Max Probability: Given fixed spherical object radii and relative distance at the time of closest approach (TCA), the projected covariance ellipse is sized and oriented to produce the maximum probability. For these reports the ratio of major-to-minor axes of the projected covariance ellipse is set using radial, in-track, and cross-track values of 100 m, 300 m, 100 m, respectively. If the combined object radius is greater than the relative distance, the maximum probability will be one; such occurrences are not addressed here. For more details on the maximum probability method, see Dr. Sal Alfano's paper titled "Relating Position Uncertainty to Maximum Conjunction Probability".
• Dilution Threshold (km): The standard deviation that produces the maximum probability defines the threshold of dilution. A smaller or larger standard deviation will produce a smaller probability. In the case of computing true probability with a smaller standard deviation, the data is of sufficient quality to associate low probability with low risk. For a larger standard deviation, this is not the case and the resulting true probability calculation becomes "diluted." If operating in this dilution region, the recommendation is to obtain better data and reassess the encounter. If time or resources do not permit, then the maximum probability should be used in place of the true probability.
• SGP4 Propagation Errors: A list of objects which were not screened because their GP data shows they have already decayed (but haven't yet been reflected in the SATCAT) or will decay prior to the end of the computation interval.