Cloud band variations and the integrated luminosity of Jupiter

The intensities of dark jovian clouds belts and bright zones are changeable. The normally dark South Equatorial Belt was so bright from late 1963 into 1964 and again in 2009–2010 that Jupiter’s integrated luminosity increased measurably. Conversely, darkening of the normally bright Equatorial Zone during 1963 and 2006–2007 may have significantly reduced the integrated luminosity. Surprisingly, the planet seems to have dimmed when the North Temperate Belt brightened from 2002 until 2007. The mean absolute magnitudes of Jupiter measured photoelectrically during the past 48 years at zero phase angle in the UBVRI band passes are U, −8.106 ± 0.005; B, −8.540 ± 0.004; V, −9.395 ± 0.003; R, −9.854 ± 0.005 and I, −9.718 ± 0.006. The geometric albedo peaks in V at 0.535 ± 0.005. The brightest apparent magnitude of the planet in the V-band is −2.94, the faintest is −1.66 and the B–V color index is +0.855. While the U, B and V values are similar to the accepted values very little has been published about R and I filter measurements. These long wavelengths represent an important part of the spectrum that significantly impacts Jupiter’s radiation budget.