def PSD_fitting_eqn_with_background(A, OmegaTrap, Gamma, FlatBackground, omega):
    """
    The value of the fitting equation:
    A / ((OmegaTrap**2 - omega**2)**2 + (omega * Gamma)**2) + FlatBackground
    to be fit to the PSD

    Parameters
    ----------
    A : float
        Fitting constant A
        A = γ**2*Γ_0*(2*K_b*T_0)/(π*m)
        where:
            γ = conversionFactor
            Γ_0 = Damping factor due to environment
            π = pi
    OmegaTrap : float
        The trapping frequency in the axis of interest 
        (in angular frequency)
    Gamma : float
        The damping factor Gamma = Γ = Γ_0 + δΓ
        where:
            Γ_0 = Damping factor due to environment
            δΓ = extra damping due to feedback or other effects
    FlatBackground : float
        Adds a constant offset to the peak to account for a flat 
        noise background
    omega : float
        The angular frequency to calculate the value of the 
        fitting equation at 

    Returns
    -------
    Value : float
        The value of the fitting equation
    """
    return A / ((OmegaTrap**2 - omega**2)**2 + omega**2 * (Gamma)**2) + FlatBackground