Element Sets

The Element Sets section on the Orbital Analysis tab displays a grid of all orbital element sets (elsets) associated with the satellite.

Understanding Element Sets

An element set (elset) is a collection of orbital parameters that describe a satellite’s orbit at a specific point in time (the epoch). Element sets are used to predict satellite positions for ground track visualization, visibility calculations, and observation planning.

Element Sets Grid

The grid displays elsets in a searchable, sortable table:

Column Description
Epoch The reference time for the orbital elements
Type Propagation type (e.g., SGP4 with Kozai mean motion, SGP4-XP with Brouwer mean motion)
Source The data provider or user who created the elset
Review Status Approval status (Approved, Pending, Rejected)
Semi-Major Axis Orbit size in kilometers
Eccentricity Orbit shape (0 = circular, approaching 1 = highly elliptical)
Inclination Orbit tilt in degrees
RAAN Right Ascension of Ascending Node in degrees
Arg of Perigee Argument of perigee in degrees
Mean Anomaly Position along the orbit in degrees
Actions Available actions for the elset

Elset Types

Type Description
SGP4 with Kozai mean motion Standard SGP4 propagation using Kozai mean elements, typically from Space-Track GP data
SGP4 with Brouwer mean motion SGP4 propagation using Brouwer mean elements
SGP4-XP with Brouwer mean motion Extended Precision SGP4 propagation using Brouwer mean elements

Selecting an Element Set

Click on any row to select that elset:

  • The selected elset is highlighted in the grid
  • The Observation Residuals chart updates to display residuals for the selected elset
  • The Orbital Elements History charts highlight the selected elset’s data point

Selecting an elset is useful for examining how well it fits the observation data in the residuals chart.

Viewing Residuals

When observation data is available, selecting an elset shows residual indicators:

  • Green checkmark - Elset has residuals data available
  • Clicking an elset with residuals scrolls the Observation Residuals section into view

Rejecting Element Sets

Authenticated users can reject element sets that they have access to:

  1. Select an elset from the grid
  2. Select the reject action (trash icon)
  3. Confirm the rejection in the dialog

Rejected elsets:

  • Are marked with “Rejected” status
  • Are excluded from approved satellite data
  • Remain visible for historical reference (Government+ users can filter to view them)

Creating New Element Sets

To create a new element set:

  1. Configure the observation time range in the Observation Residuals section
  2. Select CREATE ELSET to open the Element Set Creation Wizard
  3. Follow the wizard steps to fit orbital elements to the observation data
  4. Submit the new elset for review

The newly created elset will appear in the grid after successful creation.

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