The algorithmic approach and expected performance for the VIIRS cloud mask, sea surface temperature and land surface temperature is presented.

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Equatorial scans of Saturn at 20 µm wavelength, obtained with the Mayall 4-m telescope in 1978–79, show a continuing decrease in the specific brightness of the A and B rings as the ring plane projection approaches an edge-on apparition. The decreased brightness of the previously dominant B ring reveals more clearly a large (∼30%) difference in brightness between the east and west ansa portions of the C ring, in contrast to a barely discernible difference for the other ring ansae. The amount of eclipse cooling is compatible with a C ring particle size of ∼1 cm. We propose here that the B ring brightness variation could partially result from a decrease of absorbed insolation by a modest amount of visible scattering.

Combined photometry and radiometry of Iapetus can be used to investigate the nature of its surface and, in particular, the distribution of albedo that is responsible for the large variations in its visible and infrared brightness as it rotates. We present new 20-μm radiometric observations made in 1971–1973 and discuss these together with the photometric studies by Widorn (in 1949), Mills (in 1971), Noland et al. (in 1972–1973), and Franklin and Cook (in 1972–1974). The linear phase coefficient varies as the satellite rotates from 0.028 to 0.068 mag deg−1. When corrected for this effect, the photometric variations suggest an albedo distribution characterized by a dark area covering most of the leading hemisphere and a bright trailing hemisphere and bright south polar cap. A combined analysis of the photometry and radiometry yields a radius of 800 to 850 km and mean geometric albedos for the light and dark faces of about 0.35 and 0.07, respectively. The average phase integral of the bright hemisphere is between 1.0 and 1.5. We offer no explanation for the unique photometric properties of this satellite.

view Abstract Citations (25) References (16) Co-Reads Similar Papers Volume Content Graphics Metrics Export Citation NASA/ADS Evidence for an internal heat source in Neptune. Murphy, R. E. ; Trafton, L. M. Abstract Analysis of Morrison and Cruikshank's (1974) infrared flux measurements of Uranus and Neptune shows that Uranus is probably in equilibrium with the incident solar flux, while Neptune probably radiates 2.4 times as much energy as it receives from the sun, implying an internal heat source of 1.4 times the solar input. On the basis of very broadband data (1.5 to 300 micron) Jupiter has been shown to radiate more energy than it receives from the sun. Of the Jovian planets, only Uranus, the least massive, appears to lack an internal heat source. Publication: The Astrophysical Journal Pub Date: October 1974 DOI: 10.1086/153154 Bibcode: 1974ApJ...193..253M Keywords: Atmospheric Models; Brightness Temperature; Heat Sources; Neptune (Planet); Planetary Atmospheres; Uranus (Planet); Astronomical Models; Black Body Radiation; Heat Flux; Infrared Spectra; Jupiter (Planet); Planetary Radiation; Planetology; Radiant Flux Density; Lunar and Planetary Exploration full text sources ADS |

The 17–28 μm brightness temperature of the center of the disk of Jupiter is 136 ± 4 K. Model calculations yield an effective temperature of 142 ± 4 K at the center of the disk for a helium to hydrogen ratio He/H2 of 0. This corresponds to an effective temperature of the entire disk of 136 ± 5 K. The NEB, SEB, and STeB are shown to emit an excess flux at 20 μm when compared to the neighboring zones. The hot belts were grey in color at the time of the observations and were the source of excess 5-μm flux as well (Keay et al. 1973). The relationships between 5-μm and 20-μm flux excesses and the cloud structures are discussed.

After adjusting for the decreased Sun-Saturn distance and adjusting all measurements to B ring values only, it is shown that the temperature variations are not as large as was thought. Various models of the multilayer agglomerate of particles of Saturn's rings are evaluated. It is recommended that the difference between the 11 and 20 micron brightness temperatures should be explained by a satisfactory model.

OBSERVATIONS from aircraft of Saturn's thermal emission do not resolve the flux component of the rings from that of the planet1,2. Ground-based observations in the windows at 11 and 20 µm, which resolve the rings and disk contributions, include only a small fraction of the thermal flux and are sensitive to greenhouse effects3–6. Using new filter techniques for ground-based observations7, we have measured the relative thermal emission from the rings and disk of Saturn in the band from 29 to 43 µm. This measurement provides an important constraint for separating the thermal properties of Saturn from those of its rings.

Data are presented describing the qualities of Mauna Kea as an observatory site. Based on four years of experience, an average of 56% of nights are photometric and another 20% are spectroscopic. The median seeing is between 1 and 1.5 arc seconds, and the sky is very dark. Because of its altitude (4200 m), the site is dry and has high transparency and low sky brightness in the infrared. The median 17- to 28- m extinction coefficient is 0 '34 air mass-1. Data obtained as part of the NASA 10- m sky noise survey indicate that low noise conditions prevail at almost all times that the sky is photometric. Key words: observatory site - Hawaii - infrared - seeing - photometry

view Abstract Citations (36) References (8) Co-Reads Similar Papers Volume Content Graphics Metrics Export Citation NASA/ADS Temperatures of Saturn's Rings Murphy, Robert E. Abstract The brightness temperatures at 20 of the three components of Saturn's rings are 89 3 K, 94 2 K, and 89 t 4 K for the A, B, and C rings, respectively. The optical depths in the visible of the rings are estimated to be 0.5 t 0.15 and 0.7 1 0.1 for the A and B rings while no satisfactory estimate can be made for the C ring. The 20-p brightness temperature of the center of Saturn's disk is 97 1 2 K. Subject heading: Saturn Publication: The Astrophysical Journal Pub Date: April 1973 DOI: 10.1086/181191 Bibcode: 1973ApJ...181L..87M full text sources ADS | data products SIMBAD (1)

We review the photometric work on eclipse reappearances of Io. New observations of eclipse reappearances of Io confirm the post-eclipse brightness anomaly reported by Binder and Cruikshank (1964) but testify to its intermittent nature. A post-eclipse anomaly of approximately 0.07 mag was observed on two occasions in 1972, while observations of Europa and Ganymede showed no brightness anomaly greater than 0.01 mag. The atmospheric condensation model for the anomaly on Io is reviewed in terms of the quantity of frost required to produce the effect and the corresponding amount of gas liberated to the atmosphere upon sublimation. The observational data and the results from a stellar occultation are in general accord with the theoretical predictions of the stability of heavy gases on Io, while both observational and theoretical criteria are satisfied by a tenuous atmosphere of a heavy gas such as methane or ammonia having a surface pressure ∼10−7 bar.

WE report here photoelectric observations of two occultations of Jupiter's satellite Europa (JII) by the satellite Io (JI). The reductions in the intensity during these events exceeds predicted values (K. A., unpublished) by 80% and 55% for the nights of June 17, 1973, and June 24, 1973, respectively. The durations and absolute times of occurrence are in close agreement with the predictions, indicating that errors in the orbital parameters or in the satellite diameters are not introducing large errors into the predicted light curve. We therefore conclude that Europa has a bright polar cap extending from the north pole to latitude ∼30°.

view Abstract Citations (27) References (10) Co-Reads Similar Papers Volume Content Graphics Metrics Export Citation NASA/ADS Radii, Albedos, and 20-MICRON Brightness Temperatures of Iapetus and RHEA Murphy, Robert E. ; Cruikshank, Dale P. ; Morrison, David Abstract From infrared flux measurements at a wavelength of 20 we deduce that the radius of lapetus is 850 j 100 km and that the remarkable light variations are caused by an albedo difference between the leading and trailing hemispheres. The visual albedo is 0.04 0.01 on the leading side and 0.28 0.05 on the trailing side. For Rhea we find a radius of 725 j 100 km and an albedo of 0.57 0.07. Publication: The Astrophysical Journal Pub Date: October 1972 DOI: 10.1086/181059 Bibcode: 1972ApJ...177L..93M full text sources ADS |

Determination of the effective temperatures of the satellites by means of broad-band observations made at Mauna Kea in 1971. The temperatures of the Galilean satellites are in fair agreement with observations at shorter wavelengths and with theory. The 20-micron flux of Titan is nearly an order of magnitude lower than expected, suggesting either low surface emissivity or high atmospheric opacity between 18 and 25 micron. Hydrogen could produce the required opacity, but the abundance needed is large.

Ganymede thermal inertia data from simultaneous visual photometry and IR radiometry observations during 17 March 1971 eclipse