Acknowledgement. We thank Science for their permission to use an excerpt from:
Hanel, R., et al. 1979. Infrared observations of the Jovian system from Voyager 2. Science 206 (4421), 952-956. (Excerpt from p. 955.)
tau(nu) = I(nu)[f sec(theta) B(nu,T)]^(-1)
where I(nu) is the measured signal strength at wave number nu, f is the fraction of the instrument field of view filled by the medium, theta is the view angle measured from the normal, and B is the Planck function at the ring temperature T. Form images taken during the observation sequence (3), the bright portion of the ring in the IRIS field of view gives f=0.088; the viewing geometry gives theta=88.2 degrees; an isothermal black ring particle in thermal equilibrium with Jupiter and the sun will have a temperature of about 125 K. By using the instrument noise level as an upper limit to the ring signal, we obtain an upper limit on ring opacities (Table 2).
Table 2. Upper limit to normal optical depth of the Jovian ring; I(nu) is the upper limit of signal in the infrared spectrum of the ring.
(W cm(-2) sr(-1)/cm(-1)
Last updated Feb-27-1997