﻿IsoElevationCircle Method (, Double, Double, Double, Double)
Calculates an elevation circle centered on a satellite subpoint.

Namespace: Zeptomoby.OrbitTools.Track
Assembly: Zeptomoby.OrbitTools.Track (in Zeptomoby.OrbitTools.Track.dll) Version: 1.5.0.0 (1.5.0.0)

# Syntax

C#
```public static List<Geo> IsoElevationCircle(
this Satellite sat,
double mpe,
double degAngle,
double kmSpacing,
double kmLoft
)```
Visual Basic
```<ExtensionAttribute> _
Public Shared Function IsoElevationCircle ( _
sat As Satellite, _
mpe As Double, _
degAngle As Double, _
kmSpacing As Double, _
kmLoft As Double _
) As List(Of Geo)```
Visual C++
```[ExtensionAttribute]
public:
static List<Geo^>^ IsoElevationCircle(
Satellite^ sat,
double mpe,
double degAngle,
double kmSpacing,
double kmLoft
)```

#### Parameters

sat
Type: Satellite
The satellite.
mpe
Type: System..::..Double
Time of calculation, in minutes-past-epoch.
degAngle
Type: System..::..Double
The viewing angle, from the earth to the satellite, [0..90] degrees.
kmSpacing
Type: System..::..Double
The distance between each point, in kilometers.
kmLoft
Type: System..::..Double
The height of the set of points above the Earth ellipsoid model, in kilometers.

#### Return Value

A list of geodetic coordinate points that form a circle on the surface of the earth. The points all have the same angle of elevation to the given satellite.

#### Usage Note

In Visual Basic and C#, you can call this method as an instance method on any object of type Satellite. When you use instance method syntax to call this method, omit the first parameter. For more information, see or .

# Remarks

The returned points do not always form a perfect circle due to the Earth's equatorial bulge.

When the elevation angle of the points is specified as zero, the points form the satellite's "circle of visibility", which represents the area of the earth visible from the spacecraft.