Io: An Intense Brightening Near 5 Micrometers

  title={Io: An Intense Brightening Near 5 Micrometers},
  author={Fred C. Witteborn and Jesse Bregman and James B. Pollack},
  pages={643 - 646}
Spectrophotometric observations of the jovian satellite Io on 20 and 21 February 1978 (Universal Time) were made from 1.2 to 5.4 micrometers. Io's brightness at 4.7 to 5.4 micrometers was found to be three to five times greater at an orbital phase angle of 68� than at orbital phase angles of 23� (5.5 hours before the brightening) and 240� (20 hours after the brightening). Since the 5-micrometer albedo of Io is near unity under ordinary conditions, the observed transient phenomenon must have… 
Io: ground-based observations of hot spots.
Observations of Io in eclipse demonstrate conclusively that Io emits substantial amounts of radiation at 4.8 and 3.8 micrometers, and is most likely comprised of small hot spots in the vicinity of the volcanoes.
The lithosphere and surface of Io
Io, the innermost of the four large satellites discovered by Galileo Galilei in 1610, has a mean radius (1821.6 km) and bulk density (3.53 g cm) comparable to the Moon (Anderson et al. 2001).
Characterization of Io's Volcanic Activity by Infrared Polarimetry
The thermal emission from Io's volcanic hot spots is linearly polarized; the value determined for the index of refraction of the emitting surface is a lower bound; it is similar to that of terrestrial basalts and is somewhat less than that of sulfur.
Volcanic Activity on Io during 1987{1992: 4.8-m Photometry
Over the past 6 years we have conducted an extensive monitoring program of Io at near infrared wavelengths, in order to determine the location, frequency, and duration of the volcanic activity on
The thermal emission spectrum of Io and a determination of the heat flux from its hot spots
Observations of thermal emission from Io in the near infrared made during an eclipse were combined with unpublished 8- to 13-μm intermediate band photometry and a 16- to 22-μm spectrum to specify


Airborne infrared spectrophotometry of Mira variables
Airborne spectrophotometric observations of R Cas near minimum and maximum light, R Leo near minimum, and NML Tau near maximum are reported which were obtained over the wavelength range from 1.2 to 4
Magnetic coordinates for the Pioneer 10 Jupiter encounter
The magnetic coordinates of the Pioneer 10 spacecraft and the five innermost satellites are given around the time of Jupiter encounter, December 1–8, 1973. The D2 offset dipole model of Smith et al.
Thermal and albedo mapping of Mars during the Viking primary mission
Measurements of Martian emission and reflection reveal wide variations of surface properties and indicate the presence of a larger atmospheric contribution to the observed radiances than was
Solar flux and its variations
We present data on the solar irradiance as derived from a number of sources. An attempt was made to bring these data onto a uniform scale. The results are presented in Table IV and Figure 6.
An oscillating asymmetry to Io's sodium emission cloud
The spatial distribution of sodium emission north and south of Io was observed to have a time-dependent asymmetry correlated with Io's magnetic latitude. The spatial gradient was greatest when
Io sheath-accelerated electrons and ions
Use has been made of the Pioneer 10 and 11 measurements of the Jovian magnetic field, the Io ionospheric electron density profile, the estimate of the Io atmospheric density, and preliminary