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V.G. Tejfel, G.A. Kharitonova (Fessenkov Astrophysical Institute, Alma-Ata, Kazakhstan)
In 1997 and 1998 the special spectrophotometric observations of Jupiter were carried out to make a detailed study of the methane absorption distribution and its latitudinal variations on Jovian disk. The images of zonal spectra were recorded with CCD-camera ST-6V and 1-meter telescope. Long slit of spectrograph was oriented parallely to the equator and moved consistently from pole to pole with the step about 1 arcsec. Each serie consisted of 44-46 zonal spectra. Additionally the spectra of the equator zone and central meridian were also recorded. All spectra were divided on the spectrum of Saturn’s B-ring to exclude nonmonotonic spectral sensivity of the CCD-matrix. The central depths and equivalent widths of the methane absorption bands 619, 725, 798, and 887 nm have been determined for approximately 3200 points of Jupiter’s disk. The CCD-images of Jupiter at six wavelengths from 387 to 800 nm were used for the determinations of the limb darkening coefficients and normal albedo and their latitudinal variations. The maps of the methane absorption were presented in 2-D digital, isoline, semitone and 3-D view and clearly demonstrate the peculiarities of the absorption distribution which are different for weak and strong methane bands. Most zones of Jupiter show very small center-to-limb variations excluding high latitudes where the decrease of absorption towards limb are expressed stronger.Some differences are in the band 798 nm overlaying with the ammonia band 791 nm. The moderate and strong bands have clearly expressed zonal character of variations, but weaker band 619 nm shows chaotic variations on the disk. It may be explained if we assume that deeper layers are more affected to local convective-turbulent atmospheric motions than higher layers, where zonal currents are more effective.