Functions

The following functions are available globally.

  • See AA p. 391. AA+ result is given in kilometers

    Declaration

    Swift

    public func asteroidDiameter(magnitude: Magnitude, albedo: Double) -> Kilometer
    Show on GitHub

  • See AA p. 391. AA+ result is given in kilometers

    Declaration

    Swift

    public func apparentAsteroidDiameter(magnitude: Magnitude, albedo: Double) -> ArcSecond
    Show on GitHub

  • Compute the atmospheric refraction from the apparent altitude of a celestial body h0 that has been already measured, and from which one must substract R to find the true altitude h.

    Declaration

    Swift

    public func refraction(fromApparentAltitude h0: Degree, pressure: Millibar = 1010, temperature: Celsius = 10) -> ArcMinute

    Parameters

    h0

    The apparent altitude
    pressure

    The atmospheric pressure at Earth’s surface
    temperature

    The air temperature at Earth’s surface

    Return Value

    The refraction amplitude, in arcminutes.

    Show on GitHub

  • Compute the atmospheric refraction from the true “airless” altitude of a celestial body h that has been already calculated, and from which one must add R to find the apparent altitude h0.

    Declaration

    Swift

    public func refraction(fromTrueAltitude h: Degree, pressure: Millibar = 1010, temperature: Celsius = 10) -> ArcMinute

    Parameters

    h

    The true altitude
    pressure

    The atmospheric pressure at Earth’s surface
    temperature

    The air temperature at Earth’s surface

    Return Value

    The refraction amplitude, in arcminutes.

    Show on GitHub

  • Returns the details of a binary star.

    Declaration

    Swift

    public func binaryStarDetails(time: Double, elements: BinaryStarOrbitalElements) -> BinaryStarDetails

    Parameters

    time

    The time at which the details must be computed.
    elements

    the binary star orbital elements

    Return Value

    The details of a binary star.

    Show on GitHub

  • Return the apparent eccentricity of the binary stars orbit.

    Declaration

    Swift

    public func binaryStarApparentEccentricity(eccentricity: Double, inclination: Degree, omega: Degree) -> Double

    Parameters

    eccentricity

    The true orbital eccentricity
    inclination

    The orbit inclination
    omega

    The longitude of periastron

    Return Value

    The apparent eccentricity of the orbit, as seen on the sky.

    Show on GitHub

  • This is a noreturn function that pauses forever

    Declaration

    Swift

    public func unreachable() -> Never
    Show on GitHub

  • Undocumented

    Declaration

    Swift

    public func == (lhs: SexagesimalNotation, rhs: SexagesimalNotation) -> Bool
    Show on GitHub

  • Calculate the rise, transit and set times of a celestial body for a given location on Earth.

    One must correct the instants of the geometric rise and set of the center of the celestial body by the athomspheric refraction. Because of it, the body is actually below the horizon at the instant of its apparent rise or set. The value of 0º34’ is generally adopted for the effect of refraction at the horizon. For the Sun, the calculated times generally refer to the apparent rise or set of the upper limb of the disk, hence, 0º16’ should be added to the semidiameter

    Actually, the amount of refraction changes with air temperature, pressure and the elevation of the observer. A change of temperature from winter to summer can shift the times of sunrise and sunset by about 20 secondes in mid-northern and mid-southern latitudes. Similarly, observing sunrise or sunset over a range of barometric pressures leads to a variation of a dozen seconds in the times. However, in this chapter we shall use a mean value of the atmospheric refraction at the horizon, namely the value of 0º34’ mentionned above.

    Notes: The geographic longitude must be expressed postively west from Greenwhich, in degrees. The standard altitude, i.e. the geometric altitude of the center of the body at the time of apparent rising, setting, namely: h0 = -0º34’ = 0º.5667 for stars and planets h0 = -0º50’ = 0º.8333 for the sun h0 = +0º.125 for the moon Actually, for the moon h0 is not constant. See p.102 of AA.

    Declaration

    Swift

    public func riseTransitSet(forJulianDay julianDay: JulianDay,
                           equCoords1: EquatorialCoordinates,
                           equCoords2: EquatorialCoordinates,
                           equCoords3: EquatorialCoordinates,
                           geoCoords: GeographicCoordinates,
                           apparentRiseSetAltitude: Degree) -> RiseTransitSetTimesDetails

    Parameters

    julianDay

    the date at which one want to compute the times. MUST BE SET AT 0h UT for the given DAY.
    equCoords1

    the equatorial coordinates of the body at Date - 1 Day.
    equCoords2

    the equatorial coordinates of the body at Date.
    equCoords3

    the equatorial coordinates of the body at Date + 1 Day.
    geoCoords

    the location on Earth, with its altitude set to the standard one (see above)

    Return Value

    the times of rise, transit and set, with an indication if it is actually valid or not.

    Show on GitHub