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Cloud Structures on Neptune Observed with Keck Telescope Adaptive Optics
We report on observations obtained with the adaptive optics system atthe 10 m Keck II Telescope during engineering validation and earlyscience observing time for the adaptive optics system. We observedNeptune at near-infrared wavelengths. Angular resolution was0.05"-0.06", corresponding to a spatial scale of approximately 1000 kmat Neptune. We discuss the latitudinal structure of circumferentialcloud bands and of compact infrared-bright features seen in the southernhemisphere, as well as their variation with wavelength. We determine thevalues of I/F (proportional to the ratio of reflected intensity toincident solar flux) in the J and H infrared-wavelength bands, includingnarrowband filters where there is strong methane absorption. We use theI/F values inside and outside of methane bands to estimate the altitudeof clouds responsible for the brightest compact features in theinfrared. Our data show that, on two of our four observing dates, thebrightest region on Neptune contained highly reflective haze layerslocated below the tropopause but not deeper than a few bars.
| Photoelectric observations of lunar occultations. XIV
Observations of 314 events between March 1982 and March 1983 arepresented in the same form as in previous papers in this series. Theresults include 18 cases of duplicity of which 12 appear to be newdiscoveries. Unluckily, few cases of possible large angular diametersoccurred, and in no case can the results derived be accepted withoutreserve, these having been observed at very low altitudes withconsequent severe corruption by seeing effects. A remark on theincidence of doubles in the Hyades and its possible consequences forestimates of stellar distances is appended.
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Osservazione e dati astrometrici
| Costellazione: | Capricorno |
| Ascensione retta: | 20h43m47.73s |
| Declinazione: | -21°14'00.4" |
| Magnitudine apparente: | 8.46 |
| Distanza: | 132.1 parsec |
| Moto proprio RA: | 5.2 |
| Moto proprio Dec: | 0.5 |
| B-T magnitude: | 8.861 |
| V-T magnitude: | 8.494 |
Cataloghi e designazioni:
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