> From wupsalaa@bi.ehu.es Mon Jan 7 00:45 MST 2002 Date: Mon, 7 Jan 2002 08:45:25 +0100 (NFT) From: Agustin Sanchez Subject: BA-GRS Interaction Alert: BA-GRS interaction, IJW01/2002 Hi all, This is to alert all Jovian observers that the white oval BA is approaching the GRS and the mutual edge interaction is close to start. Enclosed is the drift chart prepared by our team member R. Morales showing the mutual approach of both anticyclones since the BA formation. The velocity of both ovals in System III is: u (BA) = 2 ± 0.7 m/s (planetographic latitude: -32.7± 0.6 deg) from 17March 2000 - 04 January 2002 u (GRS) = -4 ± 1 m/s (planetographic latitude: -22.5 ± 0.7 deg) from 18 July 2000 - 04 January 2002 According to these numbers, both ovals are approaching with a relative speed of 6 m/s, and the central encounter (both ovals at the same meridian) should take place on 13 March 2002, but of course as indicated above, the interaction will begin early. This will be the first interaction between the two large ovals since BA formation (following the BE-FA merger) in March - April 2000 (reprints of our Icarus paper on that event are available upon request and will be sent in pdf format). In September 2000 we obtained images of BA using the Hubble Space Telescope - WFPC2 camera. Measurements of the motion of features along the BA periphery indicated maximum velocities of ~ 40 m/s, much lower than the ~ 100 m/s measured in pre-merger White Ovals. We do not know if this is a true maximum peripheral velocity or a bias due to limited HST resolution. If true will mean that BA is a weaker vortex than previous White Ovals and interaction with the GRS could disrupt BA. Thus observations of this event are essential to understand its nature. I would like also to communicate to all of you that starting on January 2002 I will act as a new Discipline leader of the International Jupiter Watch - Atmospheres discipline. A new IJW web page is being modified, but images should be sent as before to Mark Vincent at NMSU for archival purposes, and myself for surveys and alerting. The IJW now will expand and will be called "International Outer Planets Watch" to cover the surveys of the four giants: Jupiter, Saturn, Uranus and Neptune. Good observations! Agustin Sanchez-Lavega **************************************************** Agustín Sánchez Lavega Dpto. Física Aplicada I E.T.S. Ingenieros Industriales y Telecomunicación Universidad del Pais Vasco Alda. Urquijo s/n 48013 BILBAO (Spain) Tfno.: 946014255 Fax: 946014178 e-mail: wupsalaa@bi.ehu.es ****************************************************