Data Fields:
- Action: The TLE Data button links to a page which provides the
TLEs used to generate the associated prediction.
- NORAD Catalog Number: NORAD Catalog Numbers of the two conjuncting
objects.
- Name: Common 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
two-line element set or operator ephemerides (green) used to produce the
prediction until the time of closest approach for the conjunction.
- 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.
- 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.
- Min Range (km): The distance between the two conjuncting objects at the
time of closest approach.
- Start (UTC): Time when the two conjuncting objects come within the
computation threshold from each other.
- TCA (UTC): Time of closest approach.
- Stop (UTC): Time when the two conjuncting objects move beyond the
computation threshold from each other.
- Relative Velocity (km/sec): Relative velocity of the two
conjuncting objects at the time of closest approach.
|
