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R. Morales, A. Sanchez-Lavega (Universidad Pais Vasco), J. Lecacheux (Observatoire Paris-Meudon), F. Colas (Bureau des Longitudes), I. Miyazaki (Okinawa, Japan)
Following the merger of Jupiter's South Temperate White Ovals BC and DE in February 1998 into a single oval BE (Sanchez-Lavega et al, Icarus, submitted), a new approach between BE and FA started on August 1998. We report here the results of our continuous CCD imaging patrol of this event using the 1-m Pic-du-Midi telescope in France (wavelength: 890 -nm methane band filter, and broad-band near infrared filter) and with a 40 -cm telescope in Japan (broad-band blue, green, red filters). The mutual longitudinal separation between BE and FA centers reduced gradually from 40 deg. in July 1998 to a mimimum distance of 14 deg in May - June 1999. Between May 9 and July 8th, the separation remained fixed in about 15 deg. A major role in a probable forthcoming merger is played ba a smaller cyclonic oval (not seen in 890-nm) located in between BE and FA. This feature is similar in reflectivity and latitude location (-31 deg planetographic) to that observed between BC and DE previous to their merger, and to the oval O1 seen westward BE after its formation. Plots of the longitude vs. time drifts of these features suggest that most probably it corresponds to the same cyclone. Average zonal velocities, sizes and morphology of these features are reported.