Events Unsorted
Close approach event data report. The report is divided into subsections with each subsection listing close approach events of secondaries with the same primary object.Available for these objects: AdvCAT
Type: Interval data. Intended to be used only with elements from this same data provider.
Availability: Reports
Data Provider Elements
| Name | Dimension | Type | Description |
|---|---|---|---|
| Object Name | Unitless | Text | The names of the secondary object involved in the close approach event. |
| SourceID | Unitless | Text | The identifier of the object as used by the ephemeris source for the object. For example, the identifier for objects that use a GPS sem or yuma file is PRN-##. |
| SSC | Unitless | Text | SSC number of the satellite with out of date TLE data for the date selected. |
| NumberID | Unitless | Text | The number identifier of the secondary object involved in the close approach event. If the object has no number identifier, then the value will be "Not Avail". |
| StringID | Unitless | Text | The string identifier of the secondary object involved in the close approach event. If the object has no string identifier, then the value will be "Not Avail". |
| Combined HardBodyRadius | SmallDistance | Real Number | The sum of the hard body radii of the primary and secondary objects. |
| Time In | Date | Real Number or Text | Start time of the event. |
| Time Out | Date | Real Number or Text | Stop time of the event. |
| Duration | Time | Real Number | The duration of the event. |
| Time at Min Sep (TMS) | Date | Real Number or Text | The time of the minimum separation between the primary and secondary threat volumes. |
| Min Separation | Distance | Real Number or Text | The separation distance between the primary and secondary threat volumes at the time of minimum separation. If the ellipsoids intersect, then the value will be "Intersect". |
| Relative Velocity | Rate | Real Number | The magnitude of the difference in the inertial velocities of the primary and secondary objects at the given time. |
| Approach Angle | Angle | Real Number or Text | The angle between the inertial velocity of the primary object and the inertial velocity of the secondary object at the given time. |
| Time of Close Appr (TCA) | Date | Real Number or Text | The time of closest approach (i.e., the minimum range) between the primary and secondary bodies. The value is computed over the time interval produced by the Range filter, which is likely larger than the time interval of the event itself. See also ConjTCA. |
| Primary Rev (TCA) | Unitless | Integer | The revolution (pass) number of the primary object at the time of close approach. |
| Secondary Rev (TCA) | Unitless | Integer | The revolution (pass) number of the secondary object at the time of close approach. |
| Min Range | Distance | Real Number | The range (i.e., distance between the primary and secondary object) at the time of close approach. |
| Range Uncertainty (TCA) | Distance | Real Number | The uncertainty in the range at the time of close approach. The uncertainty is computed by treating the ellipsoid size and orientation as a measure of the position covariance for each object. The relative position covariance is then computed and projected onto the line of sight direction between the two objects to compute the value. |
| Range Sigma (TCA) | Unitless | Real Number | The value of the range between the objects measured at TCA, expressed in terms of sigma (i.e., the scale factor by which the combined covariance ellipsoid would need to be scaled to just touch the range vector). |
| Min Range - Tangential | Distance | Real Number | The component of the minimum range vector from the primary object to the secondary object, along the tangential direction defined by the primary body (i.e., along the inertial velocity direction of the primary). |
| Min Range - CrossTrack | Distance | Real Number | The component of the minimum range vector from the primary object to the secondary object, along the cross-track direction defined by the primary body's orbit (i.e., along the orbit normal). |
| Min Range - Normal | Distance | Real Number | The component of the minimum range vector from the primary object to the secondary object, along the normal direction defined by the primary body (the normal direction completes a triad involving the tangential and cross-track directions, and is akin to the radial direction). |
| Min Range - Radial | Distance | Real Number | The component of the minimum range vector from the primary object to the secondary object, along the radial direction defined by the primary body. |
| Min Range - InTrack | Distance | Real Number | The component of the minimum range vector from the primary object to the secondary object, along the in-track direction defined by the primary body (the in-track direction completes a triad involving the radial and cross-track directions). |
| TCA Uncertainty | Time | Real Number | The uncertainty in the time of closest approach computed from the relative position uncertainty and the relative velocity at the time of the encounter. |
| EncounterPlane Sigma X | Distance | Real Number | The sigma value along the X direction for the projection of the relative position covariance into the encounter plane, as defined in Ken Chan's paper. The Y axis is normal to the encounter plane, and is aligned with the relative velocity vector at the time of close approach; the X axis lies along the line between the primary and secondary at the time of close approach. |
| EncounterPlane Sigma Z | Distance | Real Number | The sigma value along the Z direction for the projection of the relative position covariance into the encounter plane, as defined in Ken Chan's paper. The Y axis is normal to the encounter plane, and is aligned with the relative velocity vector at the time of close approach; the X axis lies along the line between the primary and secondary at the time of close approach. |
| EncounterPlane Correlation XZ | Unitless | Real Number | The XZ covariance correlation coefficient of the projection of the relative position covariance into the encounter plane, as defined in Ken Chan's paper. The Y axis is normal to the encounter plane, and is aligned with the relative velocity vector at the time of close approach; the X axis lies along the line between the primary and secondary at the time of close approach. |
| EncounterPlane Sigma Max | Distance | Real Number | The length of the major axis of the ellipse defined by the projection of the relative position covariance into the encounter plane, as defined in Ken Chan's paper. |
| EncounterPlane Sigma Min | Distance | Real Number | The length of the minor axis of the ellipse defined by the projection of the relative position covariance into the encounter plane, as defined in Ken Chan's paper. |
| EncounterPlane Sigma AspectRatio | Unitless | Real Number | The Encounter Plane Sigma Max divided by the Encounter Plane Sigma Min. |
| EncounterPlane Theta | Angle | Real Number or Text | The orientation of the principal axis of the ellipse defined by the projection of the relative position covariance into the encounter plane, as defined in Ken Chan's paper. |
| EncounterPlane Normal Sigma | Distance | Real Number | The sigma value along the Y direction for the projection of the relative position covariance into the encounter plane, as defined in Ken Chan's paper. The Y axis is normal to the encounter plane, and is aligned with the relative velocity vector at the time of close approach; the X axis lies along the line between the primary and secondary at the time of close approach. |
| Short Term Encounter Duration | Time | Real Number | The duration of the encounter as computed using the short-term encounter assumption. Reference: V.T. Coppola (2012), Paper AAS 12-248. |
| Short Term Encounter Start | Date | Real Number or Text | Start time of encounter according to short-term encounter assumption. Reference: V.T. Coppola (2012), Paper AAS 12-248. |
| Short Term Encounter Start Since TCA | Time | Real Number | Duration from TCA of the encounter start according to short-term encounter assumption. Reference: V.T. Coppola (2012), Paper AAS 12-248. |
| Short Term Encounter Stop | Date | Real Number or Text | Stop time of encounter according to short-term encounter assumption. Reference: V.T. Coppola (2012), Paper AAS 12-248. |
| Short Term Encounter Stop Since TCA | Time | Real Number | Duration from TCA of the encounter stop according to short-term encounter assumption. Reference: V.T. Coppola (2012), Paper AAS 12-248. |
| Short Term Assumption Duration | Time | Real Number | The duration that the short-term encounter assumption assumes is short. Reference: V.T. Coppola (2012), Paper AAS 12-248. |
| Collision Probability (Analytic) | Unitless | Real Number | The probability of collision computed using an analytic method based upon Ken Chan's paper. |
| Collision Probability (Numeric) | Unitless | Real Number | The probability of collision computed using a numeric method based upon Sal Alfano's paper. Collision Probability (Numeric) will return -1.0 as an error indicator when encounter plane's sigma X or sigma Z value is too small (less than 0.1 mm). |
| Collision Probability (Patera 2005) | Unitless | Real Number | The probability of collision computed using an analytic method based upon Russell Patera's paper that appeared in the J. of Guidance, Control and Dynamics, vol. 28 (6), 2005. |
| Max Collision Probability | Unitless | Real Number | The maximum probability of collision, as defined by Sal Alfano's paper. |
| Collision Probability (Nonlinear - Cylinders) | Unitless | Real Number | The probability of collision computed using a numeric method based on a method of adjoining tubes (cylinders). The collision tube is broken into small sections, the probability associated with each section is computed, and then summed. Nonlinear probability measures may return -1.0 if the user hits cancel during the computation, or for some values of the inputs, which indicates that the max sigma value should be made larger and the computation re-run. |
| Collision Probability (Nonlinear - Bundles) | Unitless | Real Number | The probability of collision computed using a numeric method based upon modeling collision tubes as bundles of abutting parallelepipeds. Nonlinear probability measures may return -1.0 if the user hits cancel during the computation, or for some values of the inputs, which indicates that the max sigma value should be made larger and the computation re-run. |
| Collision Probability (Maha) | Unitless | Real Number | The probability of collision computed based on the Mahalanabis distance method. |
| Probability Linearity Speed (Coarse) | Rate | Real Number | The coarse estimate of the relative speed needed to insure that the linear probability computation is accurate. |
| Probability Linearity Speed (Fine) | Rate | Real Number | The refined estimate of the relative speed needed to insure that the linear probability computation is accurate. |
| Sigma Dilution Threshold | Distance | Real Number | The sigma value at which the probability of collision decreases with an increase in covariance, as defined by Sal Alfano's paper. |
| ConjTCA | Date | Real Number or Text | The time of closest approach (i.e., the minimum range) between the primary and secondary objects that occurs during the conjunction (i.e., during the close approach event interval). See also Time of Close Appr (TCA) which is computed over a possibly larger time interval per event. |
| Min Conj Range | Distance | Real Number | The range between the primary and secondary object at the ConjTCA. |
| ConjTCA Min Type | Unitless | Text | The type of the minimum conjunction range: either Local Minimum or EndPoint Minimum. |
| TCA Min Type | Unitless | Text | The type of the minimum range: either Local Minimum or EndPoint Minimum. |
| TMS Min Type | Unitless | Text | The type of the minimum separation either Local Minimum or EndPoint Minimum. |
| Prim: Lat (TMS) | Latitude | Real Number or Text | The primary object's detic latitude at the time of minimum separation. |
| Prim: Long (TMS) | Longitude | Real Number or Text | The primary object's detic longitude at the time of minimum separation. |
| Prim: Alt (TMS) | Distance | Real Number | The primary object's detic altitude at the time of minimum separation. |
| Prim: Radius (TMS) | Distance | Real Number | The magnitude of the position vector of the primary object at the time of minimum separation. |
| Prim: Speed (TMS) | Rate | Real Number | The magnitude of the inertial velocity vector of the primary object at the time of minimum separation. |
| Sec: Lat (TMS) | Latitude | Real Number or Text | The secondary object's detic latitude at the time of minimum separation. |
| Sec: Long (TMS) | Longitude | Real Number or Text | The secondary object's detic longitude at the time of minimum separation. |
| Sec: Alt (TMS) | Distance | Real Number | The secondary object's detic altitude at the time of minimum separation. |
| Sec: Radius (TMS) | Distance | Real Number | The magnitude of the position vector of the secondary object at the time of minimum separation. |
| Sec: Speed (TMS) | Rate | Real Number | The magnitude of the inertial velocity vector of the secondary object at the time of minimum separation. |
| Prim: Lat (TCA) | Latitude | Real Number or Text | The primary object's detic latitude at the time of close approach. |
| Prim: Long (TCA) | Longitude | Real Number or Text | The primary object's detic longitude at the time of close approach. |
| Prim: Alt (TCA) | Distance | Real Number | The primary object's detic altitude at the time of close approach. |
| Prim: Radius (TCA) | Distance | Real Number | The magnitude of the position vector of the primary object at the time of close approach. |
| Prim: Speed (TCA) | Rate | Real Number | The magnitude of the inertial velocity vector of the primary object at the time of close approach. |
| Sec: Lat (TCA) | Latitude | Real Number or Text | The secondary object's detic latitude at the time of close approach. |
| Sec: Long (TCA) | Longitude | Real Number or Text | The secondary object's detic longitude at the time of close approach. |
| Sec: Alt (TCA) | Distance | Real Number | The secondary object's detic altitude at the time of close approach. |
| Sec: Radius (TCA) | Distance | Real Number | The magnitude of the position vector of the secondary object at the time of close approach. |
| Sec: Speed (TCA) | Rate | Real Number | The magnitude of the position vector of the secondary object at the time of close approach. |