Definition of "octupole" []

• Anything having eight poles or electrodes, but especially a combination of two quadrupoles used for controlling beams of charged particles (noun)

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• "The reported anomalies the team examined are many – two prominent cold spots, strength of the quadrupole, lack of large angular scale CMB power, alignment of the quadrupole and octupole components, hemispherical or dipole power asymmetry, to name but a handful – but the reasons for the apparent anomalies are few."
• "Nevertheless, the supermode idea is still constrained — the dipole cancels, but there are higher-order effects (quadrupole and octupole) that are observable."
• "We show that an adiabatic superhorizon perturbation in a LCDM universe does not generate a CMB temperature dipole, and we derive constraints to the amplitude and wavelength of a superhorizon potential perturbation from measurements of the CMB quadrupole and octupole."