JHK photometry of selected Trojan and Hilda asteroids is presented and compared with that of main belt asteroids and laboratory samples, none of which yields a completely satisfactory match. Leading Trojans and Hildas show similar and homogenous JHK colors, while the trailing Trojans appear more heterogeneous.

Periodic comet Tempel-2, first discovered in 1873, is a possible target of a spacecraft flyby in the 1980s. Accurate physical measurements of this comet have only recently been attempted. Few spectrophotometric data exist for any faint comet, but we present here such data for Tempel-2 at a heliocentric distance of 2.97 AU. The data were obtained during an outburst in which the comet exhibited heightened CN and C3 emission over a quiescent phase. Comet flares of such magnitude are exceptional, and are particularly surprising for a periodic comet at such a large heliocentric distance.

An eclipse of Titan by Saturn was observed on December 20, 1979, to measure the aerosol content in the atmosphere of Saturn. The measurements were made with the 74-in. telescope of the Helwan Observatory, Egypt, in the bandpass 6300–7300 Å and extend to ∼5 magnitudes of eclipse darkening. The faint portion of the lightcurve unambiguously requires the presence of aerosol in the lower stratosphere of Saturn. The aerosol extends to at least 20 km above the tropopause and has a one-way stratospheric vertical optical depth of 0.4−0.02+0.04 at 6700 Å. The results apply to the sunset terminator at a cronographic latitude of 23°S.

Spectrophotometric light curves of 12 Galilean satellite eclipses are reported. The observations were made in 20 to 30 channels over the wavelength range 3240 to 10,500 Å using the 200-in. telescope. The initial data processing is described. These data measure the Jovian aerosol content in the lower stratosphere and uppermost troposhere and the methane abundance in the lower stratosphere. The data are consistent with a lack of limb darkening on the Galilean satellites. The orbit of Callisto is shown to be inclined 0.08 ± 0.02° to the equatorial plane of Jupiter.

Narrowband spectrophotometry of satellite eclipses is presented for each of the Galilean satellites. Comparing the partially eclipsed full-phase satellite disk to the uneclopsed disk can reveal colorimetric inhomogeneities on the surface. The trailing half-disk of Ganymede is slightly blue compared to the leading half-disk. The trailing and leading half-disks of Callisto are similar to each other, as are the northern and southern half-disks. The northern half-disk shows evidence of blue and red portions. The trailing half-disk of Europa is redder than the leading half-disk.

The Galilean satellite eclipse technique for measuring the aerosol distribution in the upper Jovian atmosphere is described and applied using 30 color observations of the 13 May 1972 eclipse of Ganymede obtained with the 5-m Hale telescope. This event probes the South Temperate Zone. The observed aerosol lies above the visible cloud tops, is very tenuous and varies with altitude, increasing rapidly with downward passage through the tropopause. The aerosol extinction coefficient, κa (λ1.05 μm), is ∼1.1 × 10−9 cm−1 in the lower stratosphere and ∼1.1 × 10−8 cm−1 at the tropopause. The 1σ uncertainty in these values does not exceed 50% The observations require some aerosol above the tropopause but do not clearly determine its structure. The present analysis emphasizes an extended haze distribution, but the alternate possibility is not excluded that the stratospheric aerosol resides in a thin layer. The aerosol extinction increases with decreasing wavelength and indicates the particle radius to be ⩽0.2 μm. Larger radii are impossible. These overall results confirm Axel's (1972) suggestion of a small quantity of dust above the Jovian cloud tops and the optical depths are consistent with those required to explain the low uv albedo.

view Abstract Citations (33) References (6) Co-Reads Similar Papers Volume Content Graphics Metrics Export Citation NASA/ADS The Structure of the Fornax Dwarf Galaxy Hodge, P. W. ; Smith, Dale W. Abstract New photoelectric surface photometry and new star counts are combined with previously published data to reexamine the structure of the Fornax dwarf galaxy. The new star counts show excellent agreement with King's dynamical models and with de Vaticouleurs and Ables's star counts. The new photoelectric photometry, which covers only the central regions, fits the de Vaucouleurs and Ables photometry at a 5', but they disagree at the center. Their outer photometry shows a different slope from that of the star counts. Subject headings: galaxies, individual - galaxies, photometry of Publication: The Astrophysical Journal Pub Date: February 1974 DOI: 10.1086/152678 Bibcode: 1974ApJ...188...19H full text sources ADS | data products SIMBAD (7) NED (7)

Twelve eclipse light curves for the Galilean satellites have been observed at 30 colors. The shape of the curves depend upon Jovian atmospheric properties such as Rayleigh scattering, aerosol distribution, molecular absorption, scale height and cloud top altitude, as well as the satellite diameter. Different zenographic latitudes and longitudes along the sunrise and sunset terminator have been observed. Very long absorption path lengths are obtained compared to normal incidence because of the tangential passage of the Sun's rays. Refractive tails are observed in most cases which allow aerosol distributions to be determined. The other atmospheric properties may also be derived.