Spatially resolved spectroscopic observations of Jupiter during the 1987 opposition

Abstract

Spectroscopic observations in the spectral region AA 6000--6600 ~, of major belts and zones of Jupiter have been carded out at Calar Alto Observatory (Spain) during the 1987 opposition, in support to the International Jupiter Watch Program. More than a hundred long-slit, medium resolution spectra have been taken at the coud6 focus of the 1.52 m telescope. The longitudinal and latitudinal distribution of the equivalent widths of the methane and ammonia absorption bands at 6190A and 6450A have been investigated. Unlike the CH4-6190~, band, the longitudinal distribution in the NH~-6450 ,~ band shows asymmetries in some of the Jovian regions analyzed, being the absorption greater at West than at East limbs. These results are interpreted in terms of inhomogeneous scattering models by the simultaneous variation of the NH3 cloud optical thickness and its altitude level. The north--south scans show little latitudinal dependence on absorption in both methane and ammonia bands, although some relationship could be established between the absorption and relative continuum refleetivity variation.Resnmen. Se presentan los resultados obtenidos de las observaciones espectrosc6picas de las principales zonas y cinturones de Jfipiter realizadas durante la oposici6n de 1987 como una contribuci6n al International Jupiter Watch Program. Las observaciones fueron Ilevadas a cabo haciendo uso del foco coud6 del telescopio de 1.52 m del observatorio hispanoalem~n de Calar Alto (Espafia), habi6ndose obtenido algo mils de cien espectros, de resoluci6n media, en la regi6n espectral de 6000-6600 ,~. Se exponen los resultados de las anchuras equivalentes de Ins bandas de absorci6n del metano en 6190A, y del amoniaco en 6450 A,, estudi~ndose, al mismo tiempo, la distribuci6n tanto longitudinal como latitudinal de las mismas. Mientras que los resultados para ia banda del metano presentan un comportamiento sim6trico en todas ias regiones analizadas, las anchuras equivalentes para la banda NH3-6450 A presentan un comportamiento asim6trico en algunas regiones del planeta, con una mayor absorci6n hacia el limbo del oeste que hacia el del este. Los resultados son interpretados en base aun modelo de 'scattering' no homog6neo, variando, simultfineamente, el espesor 6ptico y la altitud de la nube de amoniaco. Los espectros tornados en la direcci6n norte-sur, aunque presentan una dependencia latitudinal pequefia en la absorci6n de las bandas mencionadas, sugieren una relaci6n entre la absorci6n y las variaciones de reflectividad en el continuo.

Charge‐coupled device spectral images of spatially resolved regions of Jupiter in the 6190‐ and 8900‐Å methane and 6450‐Å ammonia bands during the 1989 Opposition

“…With the purpose of studying the long-term evolution in the absorptive properties of selected regions on Jupiter, we obtained several data sets in the visible bands over the last few years [Moreno et al, 1988;Molina et al, 1989;Molina, 1989, 1991]. These data are useful within the framework of the International Jupiter Watch [Russell et al, 1990], a program designed to coordinate Jupiter's observations.…”

Comparative Analysis of the Behavior of Weak Absorption Bands of Ammonia at 552 and 645 Nm in the Spectrum of Jupiter

“…Therefore, specific techniques are required in order to correctly draw the level of the continuous spectrum and to isolate precisely the ammonia bands' profiles. This problem is discussed in detail in [22][23][24] and in our articles, for example, in [25]. To compare the latitudinal behavior of the absorption in two ammonia bands, in addition to equivalent widths, we made an estimate of the corresponding equivalent absorption paths.…”