418 California, University, Berkeley, Calif. 335 Max-Planck-Institut fuer Physik und Astrophysik, Garching, Federal Republic of Germany 166 Marseille, Observatoire, France 139 California, University, Los Angeles, CA 136 Owens Valley Radio Observatory, Pasadena, CA 129 California, University, La Jolla, Calif. 118 California, University, Los Angeles, Calif. 109 Marseille, Observatoire, Marseille, France 97 Minnesota, University, Minneapolis, MN 86 California, University, Los Alamos, N. Mex. 84 Minnesota, University, Minneapolis, Minn. 79 Armagh Observatory, Northern Ireland 73 Queen Mary and Westfield College, London, United Kingdom 71 North Carolina, University, Chapel Hill 68 California, University, Santa Barbara 64 California, University, San Diego, Calif. 63 Dominion Radio Astrophysical Observatory, Penticton, Canada 63 Cornell Univ., Ithaca, NY, US 61 Victoria, University, Victoria, British Columbia, Canada 61 Observatorium Hoher List, Daun, West Germany 60 Center for Astrophysics, Cambridge, MA, US 59 Multiple Mirror Telescope Observatory, Tucson, AZ 58 Smithsonian Astrophysical Observatory, Cambridge, MA 57 Univ. of Tokyo, Tokyo, Japan 57 Australia Telescope National Facility, Epping 57 Andalucia, Instituto de Astrofisica, Granada, Spain 55 International Ultraviolet Explorer Observatory, Madrid, Spain 55 Cambridge University, Observatories, Cambridge, England 54 Aerospace Corp., Space Sciences Laboratory, Los Angeles, CA 53 Mullard Radio Astronomy Observatory, Cavendish Laboratory, Madingley Road, Cambridge CB3 0HE, UK 53 IBM Thomas J. Watson Research Center, Yorktown Heights, NY 52 Rio Grande do Sul, Universidade Federal, Porto Alegre, Brazil 52 Dwingeloo, Radiosterrenwacht, Netherlands 51 Strasbourg, Observatoire, Strasbourg, France 51 Sao Paulo, Universidade, Sao Paulo, Brazil 51 SERC, Rutherford Appleton Laboratory, Didcot, England 51 Pic-du-Midi et Toulouse, Observatoires, Toulouse, France 51 ESA, Villafranca Satellite Tracking Station, Madrid, Spain 50 Yerkes Observatory, Williams Bay, Wis. 50 New Mexico Institute of Mining and Technology, Socorro 50 National Astronomy and Ionosphere Center, Ithaca, NY 49 Warner and Swasey Observatory, Cleveland, OH 49 Iowa State University of Science and Technology, Ames 48 Royal Greenwich Observatory, Madingley Road, Cambridge CB3 0EZ, UK 48 Kiepenheuer-Institut fuer Sonnenphysik, Freiburg im Breisgau, West Germany 48 CONICET, Instituto de Astronomia y Fisica del Espacio, Buenos Aires, Argentina 47 Massachusetts Institute of Technology, Cambridge, MA, US 46 Wise Observatory, Tel Aviv, Israel 46 Catholic University of America, Washington, DC 45 University of Science and Technology of China, Hefei, People's Republic of China 45 Nuffield Radio Astronomy Laboratories, Jodrell Bank, England 45 CNR, Laboratorio di Fisica Cosmica e Tecnologie Relative, Milan, Italy 44 Univ. Nacional Autonoma de Mexico, Coyoacan 44 Science and Engineering Research Council, Rutherford Appleton Laboratory, Didcot, Oxon, England 44 Landessternwarte Koenigstuhl, Heidelberg, Germany 43 Univ. of Toronto, Toronto, Ontario, Canada 43 Physical Research Laboratory, Ahmedabad, India 43 Lausanne, Universite, Chavannes-des-Bois, Switzerland 42 The Citadel, Charleston, SC 42 Beijing Observatory, People's Republic of China 41 Michigan State University, East Lansing, Mich. 41 Kiepenheuer-Institut fuer Sonnenphysik, Freiburg im Breisgau, Federal Republic of Germany 41 Jet Propulsion Laboratory, Pasadena, CA, US 41 Helsinki, University, Observatory, Helsinki, Finland 41 Berlin, Technische Universitaet, Berlin, West Germany 40 Space Research Astronomical Observatory, Utrecht, Netherlands 40 Australia Telescope National Facility, CSIRO, PO Box 76, Epping, NSW 2121, Australia 39 School of Physics and Space Research, University of Birmingham, Edgbaston, Birmingham B15 2TT, UK 39 Raman Research Institute, Bangalore, India 39 Bordeaux I, Universite, Observatoire, Floirac, France 39 Big Bear Solar Observatory, Pasadena, CA 39 Bartol Research Institute, Newark, DE 38 Stanford Univ., Stanford, CA, US 38 South African Astronomical Observatory, PO Box 9, Observatory 7935, South Africa 37 Yale Univ., New Haven, CT, US 37 Mullard Space Science Laboratory, University College London, Holmbury St Mary, Dorking, Surrey RH5 6NT, UK 37 ESA, European Space Research and Technology Centre, Noordwijk, Netherlands 36 EXOSAT Observatory, Darmstadt, West Germany 36 California, University, Livermore, Calif. 36 Bell Telephone Laboratories, Inc., Murray Hill, N.J. 35 Univ. di Padova, Padova, Italy 35 Observatories of the Carnegie Institution of Washington, Pasadena, CA 34 Besancon, Observatoire, Besancon, France 33 New South Wales, University, Kensington, Australia 33 NASA, Johnson Space Center, Houston, Tex. 33 McDonald Observatory, Fort Davis, Tex. 33 Leuven, Katholieke Universiteit, Heverlee, Belgium 33 Instituto de Astronomia y Fisica del Espacio, Buenos Aires, Argentina 33 Bureau des Longitudes, Service de Mecanique Celeste, Paris, France 33 Andalucia, Inst. de Astrofisica, Granada, Spain 33 AN SSSR, Astronomicheskii Sovet, Moscow, USSR 32 Univ. of Wisconsin-Madison, Madison, WI, US 32 Univ. de Montreal, Montreal, Quebec, Canada 32 Observatorio Astronomico Nacional, Madrid, Spain 32 Monash University, Clayton, Victoria, Australia 32 Massachusetts Inst. of Technology, Cambridge, MA, US 32 Krymskaia Astrofizicheskaia Observatoriia, Nauchny, Ukrainian SSR 32 Institute of Astronomy, Cambridge, UK 32 Centro de Investigaciones de Astronomia, Merida, Venezuela 32 Calgary, University, Calgary, Alberta, Canada 31 Virginia Polytechnic Institute and State University, Blacksburg, Va. 31 University of Minnesota, Minneapolis, MN, US 31 University of Manchester, Nuffield Radio Astronomy Laboratories, Jodrell Bank, Macclesfield, Cheshire SK11 9DL, UK 31 Rutherford Appleton Laboratory, Didcot, England 31 La Plata, Universidad Nacional, Argentina 30 Space Telescope Science Institute, 3700 San Martin Drive, Baltimore, MD 21218, USA 30 South African Astronomical Observatory, PO Box 9, Observatory 7935, Cape, South Africa 30 Salonika, University, Salonika, Greece 30 Russian Academy of Sciences, Space Research Inst., Moscow, Russia 30 Royal Greenwich Observatory, Santa Cruz de la Palma, Spain 30 New Mexico State Univ., Las Cruces, NM, US 30 NASA/Fermilab Astrophysics Center, Batavia, IL 30 Instituto de Pesquisas Espaciais, Sao Jose dos Campos, Brazil 30 Institute of Astronomy, University of Cambridge, Madingley Road, Cambridge CB3 0HA, UK 30 Athens, National Observatory, Greece 30 Armagh Observatory, Armagh, Northern Ireland 29 Massachusetts Inst. of Tech., Cambridge, MA, US 29 Kiel, Universitaet, Institut fuer theoretische Physik und Sternwarte, Federal Republic of Germany 29 Kiel, Neue Universitaet, Institut fuer theoretische Physik und Sternwarte, Kiel, West Germany 29 Department of Astronomy, University of Cape Town, Rondebosch 7700, South Africa 29 Canterbury, University, Christchurch, New Zealand 28 Virginia Polytechnic Institute and State University, Blacksburg 28 Nuffield Radio Astronomy Labs., Jodrell Bank, United Kingdom 28 National Center for Atmospheric Research, Boulder, CO, US 28 National Astronomy and Ionosphere Center, Ithaca, N.Y. 28 NASA, Marshall Space Flight Center, Space Sciences Laboratory, Huntsville, Ala. 28 Lab. for Space Research, Leiden, Netherlands 28 Dwingeloo, Radiosterrenwacht, Dwingeloo, Netherlands 28 Department of Physics and Astronomy, University of Leicester, University Road, Leicester LE1 7RH, UK 27 Potchefstroom University for Christian Higher Education, Republic of South Africa 27 New Mexico, University, Albuquerque, NM 27 Institute of Physical and Chemical Research, Wako, Japan 27 Haute-Provence, Observatoire, Saint-Michel-l'Observatoire, Alpes-de-Haute-Provence, France 27 Ecole Polytechnique, Palaiseau, Essonne, France 26 Virginia Polytechnic Institute and State University, Blacksburg, VA 26 University of Maryland, College Park, MD, US 26 Universita di Padova, Padova, Italy 26 Tuorla Observatory, Piikkio, Finland 26 Space Research Institute, Moscow, Russia 26 NOAA, Space Environment Laboratory, Boulder, CO 26 Konkoly Observatory, Budapest, Hungary 26 Inst. of Astronomy, Cambridge, UK 26 Caltech, Pasadena, CA, US 25 Paris XI, Universite, Orsay, Essonne, France 25 Observatoire Astronomique, Strasbourg, France 25 Observatoire Astronomique du Mont Megantic, Quebec, Canada 25 Leuven, Katholieke Universiteit, Louvain, Belgium 25 Instituto Argentino de Radioastronomia, Villa Elisa, Argentina 25 Centre d'Etudes et de Recherches Geodynamiques et Astronomiques, Grasse, Alpes-Maritimes, France 25 CNRS, Service d'Aeronomie, Verrieres-le-Buisson, France 24 Universidad de Los Andes, Merida, Venezuela 24 Univ. of Amsterdam, Amsterdam, Netherlands 24 Polish Academy of Sciences, Astronomical Centre, Warsaw, Poland 24 Observatories of the Carnegie Institution, Pasadena, CA 24 National Astronomy and Ionosphere Center 24 Nanjing University, People's Republic of China 24 NASA, Ames Research Center, Space Science Div., Moffett Field, CA 24 Kiel, Universitaet, Institut fuer Theoretische Physik und Sternwarte, Federal Republic of Germany 24 Jet Propulsion Lab., Cal. Inst. of Tech., Pasadena, CA, US 24 Aerospace Corp., Los Angeles, CA 23 University of Manchester, Nuffield Radio Astronomy Laboratories, Jodrell Bank, Macclesfield, Cheshire SK11 9DL 23 University of Illinois at Urbana-Champaign, Urbana, IL, US 23 Universities Space Research Association, Greenbelt, MD 23 Tartu Astrophysical Observatory, Toravere, Estonia 23 Rutherford Appleton Lab., Didcot, United Kingdom 23 Royal Greenwich Observatory, Madingley Road, Cambridge CB3 0EZ 23 Polish Academy of Sciences, Astronomical Center, Warsaw, Poland 23 NOAA, Space Environment Laboratory, Boulder, Colo. 23 Ministerio de Educacion de Chile, Instituto Isaac Newton, Santiago 23 International Centre for Theoretical Physics, Trieste, Italy 23 Innsbruck, Universitaet, Innsbruck, Austria 23 California, University, Santa Barbara, CA 23 CNR, Istituto di Tecnologie e Studio delle Radiazioni Extraterrestri, Bologna, Italy 23 American Science and Engineering, Inc., Cambridge, Mass. 22 University of Toronto, Toronto, Ontario, Canada 22 Universite de Montreal, Montreal, Quebec, Canada 22 Royal Observatory, Blackford Hill, Edinburgh EH9 3HJ, UK 22 Purple Mountain Observatory, Nanjing, People's Republic of China 22 Purdue University, West Lafayette, IN 22 North Carolina Univ., Chapel Hill 22 New Mexico State University, Las Cruces, N. Mex. 22 National Radio Astronomy Observatory 22 NASA, Marshall Space Flight Center, Space Science Laboratory, Huntsville, AL 22 NASA, Infrared Telescope Facility, Mauna Kea, HI 22 NASA, Ames Research Center, Space Sciences Div., Moffett Field, Calif. 22 Mullard Radio Astronomy Observatory, Cavendish Laboratory, Madingley Road, Cambridge CB3 0HE 22 Max-Planck-Gesellschaft, Jena, Germany 22 Illinois, University, Observatory, Urbana, Ill. 22 IBM Thomas J. Watson Research Center, Yorktown Heights, N.Y. 22 Franklin Institute, Bartol Research Foundation, Newark, DE 22 CSIRO, Australia Telescope National Facility, Epping 22 CNR, Istituto di Fisica dello Spazio Interplanetario, Frascati, Italy 22 Astronomisches Rechen-Institut, Heidelberg, Federal Republic of Germany 21 University of Virginia, Charlottesville, VA, US 21 Universities Space Research Association 21 Universitaets-Sternwarte, Munich, Federal Republic of Germany 21 Southern California, University, Los Angeles, CA 21 School of Physics and Space Research, University of Birmingham, Edgbaston, Birmingham B15 2TT 21 New Mexico State University, Las Cruces, NM, US 21 Liege, Universite de l'Etat, Cointe-Ougree, Belgium 21 Las Campanas Observatory, La Serena, Chile 21 Koeln, Univ., Cologne, Germany 21 Kiel, Universitaet, Institut fuer theoretische Physik und Sternwarte, West Germany 21 ISRO Satellite Centre, Bangalore, India 21 ESA, Astronomy Div., Madrid, Spain 21 Department of Physics, Keele University, Keele, Staffordshire ST5 5BG, UK 21 Centro Astronomico Hispano-Aleman, Almeria, Spain 21 California, University, Irvine, Calif. 21 CNR, Gruppo Nazionale per l'Astronomia, Padua, Italy 21 Atmospheric and Environmental Research, Inc., Cambridge, MA 21 Anglo-Australian Observatory, PO Box 296, Epping, NSW 2121, Australia 20 Univ. Tuebingen, Tuebingen, Germany 20 USAF, Geophysics Laboratory, Bedford, MA 20 Observatorium Hoher List, Daun, Federal Republic of Germany 20 Kiel, Neue Universitaet, Sternwarte, Kiel, West Germany 20 Fermi National Accelerator Laboratory, Batavia, IL 20 Eotvos Lorand Tudomanyegyetem, Budapest, Hungary 20 Ecole Polytechnique, Palaiseau, France 20 Case Western Reserve University, Cleveland, OH 20 California, University, Santa Cruz, Calif. 20 California, University, Los Alamos Scientific Laboratory, Los Alamos, N. Mex. 20 C. E. Kenneth Mees Observatory, Rochester, NY 20 Bordeaux, Observatoire, Floirac, France 20 Bell Telephone Laboratories, Inc., Murray Hill, NJ 19 University of Hong Kong, Hong Kong 19 University of California, San Diego, La Jolla, CA, US 19 Southampton, University, Southampton, England 19 Royal Observatory, Blackford Hill, Edinburgh EH9 3HJ 19 Pontificia Universidad Catolica de Chile, Santiago 19 National Center for Atmospheric Research, Boulder, CO 19 NASA, Johnson Space Center, Houston, TX 19 Kiel, Univ., Inst. fuer Theoretische Physik und Sternwarte, Germany 19 Hampden-Sydney College, VA 19 Erlangen-Nuernberg, Universitaet, Erlangen, West Germany 19 Ceskoslovenska Akademie Ved, Astronomicky Ustav, Ondrejov, Czechoslovakia 19 CNRS, Service d'Aeronomie, Verrieres-le-Buisson, Essonne, France 19 Bordeaux I, Universite, Observatoire, Floirac, Gironde, France 19 Beijing University, People's Republic of China 18 Western Ontario Univ., London, Canada 18 Warsaw Univ. Observatory, Warszawa, Poland 18 Utah, University, Salt Lake City, Utah 18 Univ. Bonn, Bonn, Germany 18 U.S. Navy, Center for Advanced Space Sensing, Washington 18 Tel Aviv Univ., Tel Aviv, Israel 18 Observatorio Astronomico Nacional, Ensenada, Mexico 18 Nationaal Instituut voor Kernfysica en Hoge Energie Fysica, Netherlands 18 Institut d'Estudis Catalans, Spain 18 Firenze, Univ., Florence, Italy 18 Department of Physics and Astronomy, University of Leicester, University Road, Leicester LE1 7RH 18 Dansk Rumforskningsinstitut, Lyngby, Denmark 18 Center for High Energy Astrophysics, Netherlands 18 Catania, Osservatorio Astrofisico, Italy 18 Cambridge, University, Observatories, England 18 California, University, Santa Barbara, Calif. 18 CONICET, Instituto Argentino de Radioastronomia, Villa Elisa, Argentina 18 CNR, Gruppo Nazionale di Astronomia, Italy 17 Vanderbilt Univ., Nashville, TN, US 17 Valencia Univ., Burjasot, Spain 17 Uttar Pradesh State Observatory, Nainital, India 17 Univ. of Illinois at Urbana-Champaign, Urbana, IL, US 17 Univ. of Cambridge, Cambridge, UK 17 Univ. of California at San Diego, La Jolla, CA, US 17 Univ. of British Columbia, Vancouver, BC, Canada 17 Toulouse, Observatoire, France 17 Specola Vaticana, Vatican City State 17 Smithsonian Astrophysical Observatory, Cambridge, MA, US 17 Saint Mary's University, Halifax, Nova Scotia, Canada 17 Rio Grande do Sul, Univ. Federal, Porto Alegre, Brazil 17 National Research Council, Victoria, BC, Canada 17 National Bureau of Standards, Washington, D.C. 17 National Bureau of Standards, Quantum Physics Div., Boulder, CO 17 Nanjing University, Nanjing, People's Republic of China 17 Lille I, Universite, Villeneuve-d'Ascq, France 17 Berlin, Technische Universitaet 17 Astronomska Opservatorija, Belgrade, Yugoslavia 16 Vainu Bappu Observatory, Kavalur, India 16 Universitat de Barcelona, Barcelona, Spain 16 U.S. Naval Observatory, Flagstaff, AZ, US 16 Spetsial'naia Astrofizicheskaia Observatoriia, Nizhni Arkhyz, USSR 16 Queen Mary and Westfield College, London, UK 16 Planetary Science Institute, Tucson, AZ 16 Pic-du-Midi et Toulouse, Observatoires, Bagneres-de-Bigorre, Hautes-Pyrenees, France 16 Physics Department, University of Durham, South Road, Durham DH1 3LE, UK 16 Niels Bohr Institute, Copenhagen, Denmark 16 New Mexico, University, Albuquerque, N. Mex. 16 National Astronomy and Ionosphere Center, Arecibo, PR 16 Max-Planck-Institut fur Astrophysik, Karl-Schwarzschild-Strasse 1, 85748 Garching, Germany 16 International School for Advanced Studies, Trieste, Italy 16 Grenoble I, Universite, Saint-Martin-d'Heres, France 16 Fonds National de la Recherche Scientifique, Brussels, Belgium 16 Carter Observatory, Wellington, New Zealand 16 California, University, Santa Cruz, CA 16 CNR, Laboratorio di Tecnologie e Studio delle Radiazioni Extraterrestri, Bologna, Italy 16 C. E. Kenneth Mees Observatory, Rochester, N.Y. 16 Astronomisches Rechen-Institut, Heidelberg, West Germany 16 Akademiia Nauk SSSR, Fizicheskii Institut, Moscow, USSR 16 Akademiia Nauk SSSR, Astronomicheskii Sovet, Moscow, USSR 15 York Univ., North York, Canada 15 Westerbork, Radiosterrenwacht, Zwiggelte, Netherlands 15 Waikato, University, Hamilton, New Zealand 15 Tokyo Institute of Technology, Tokyo, Japan 15 Strasbourg, Observatoire Astronomique, France 15 Sachs/Freeman Associates, Inc., Bowie, MD 15 Owens Valley Radio Observatory, Pasadena, CA, US 15 Owens Valley Radio Observatory, Big Pine, CA 15 New Mexico Inst. of Mining and Technology, Socorro 15 NASA, Ames Research Center, Theoretical and Planetary Studies Branch, Moffett Field, Calif. 15 Ministerio de Educacion de Chile, Santiago, Chile 15 Middle East Technical University, Ankara, Turkey 15 Kiel, Neue Universitaet, Institut fuer Theoretische Physik und Sternwarte, Kiel, West Germany 15 Instituto Argentino de Radioastronomia, Villa Elisa 15 Institut d'Estudis Catalans, Barcelona, Spain 15 Harvard-Smithsonian Center for Astrophysics, 60 Garden Street, Cambridge, MA 02138, USA 15 Fraunhofer Institut, Freiburg im Breisgau, West Germany 15 European Southern Observatory, Santiago de Chile, Chile 15 College of the Holy Cross, Worcester, MA 15 California, University, San Diego, CA 15 Ball Aerospace Systems Group, Boulder, CO 15 Astrophysikalisches Institut Potsdam, Potsdam, Germany 15 Akademiia Nauk SSSR, Institut Prikladnoi Matematiki, Moscow, USSR 15 AN SSSR, Fiziko-Tekhnicheskii Institut, Leningrad, USSR 15 AN SSSR, Fizicheskii Institut, Moscow, USSR 14 Yunnan Observatory, Kunming, People's Republic of China 14 Universidade de Sao Paulo, Sao Paulo, Brazil 14 Univ. de Sao Paulo, Sao Paulo, Brazil 14 USAF, Geophysics Laboratory, Hanscom AFB, MA 14 U.S. Naval Observatory, Flagstaff, Ariz. 14 Toulouse, Observatoire, Toulouse, France 14 Sterrewacht Leiden, Postbus 9513, 2300 RA Leiden, The Netherlands 14 Radiosterrenwacht, Dwingeloo, Netherlands 14 Radio Astronomy Observatory, Ann Arbor, MI 14 Palomar Observatory, California Inst. of Technology, Pasadena, CA, US 14 Oslo, Universitetet, Oslo, Norway 14 New Mexico Institute of Mining and Technology, Socorro, N. Mex. 14 Ministerio de Educacion de Chile, Instituto Isaac Newton, Santiago, Chile 14 Max-Planck-Institut fuer Radioastronomie 14 Magyar Tudomanyos Akademia, Kozponti Fizikai Kutato Intezet, Budapest, Hungary 14 MPI fuer Extraterrestrische Physik, Garching, Germany 14 Leander McCormick Observatory, Charlottesville, VA 14 Kiepenheuer-Inst. fuer Sonnenphysik, Freiburg, Germany 14 Kiepenheuer-Inst. fuer Sonnenphysik, Freiburg im Breisgau, Germany 14 Kernforschungszentrum Karlsruhe GmbH, Federal Republic of Germany 14 Jet Propulsion Lab., California Inst. of Tech., Pasadena, CA, US 14 Instituto Nacional de Astrofisica, Optica y Electronica, Puebla, Mexico 14 Erwin W. Fick Observatory, Ames, Iowa 14 Department of Physics, University of Durham, South Road, Durham DH1 3LE, UK 14 Commissariat a l'Energie Atomique, Service d'Astrophysique, Gif-sur-Yvette, Essonne, France 14 CNR, Ist. di Radioastronomia 14 Beijing Astronomical Observatory, People's Republic of China 14 Bartol Research Inst., Newark, DE 14 Australia Telescope National Facility, Epping, Australia 14 Athens, National Capodistrian University, Greece 14 Astrophysics, Department of Physics, Keble Road, Oxford OX1 3RH, UK 14 Akademiia Nauk SSSR, Fiziko-Tekhnicheskii Institut, Leningrad, USSR 14 Aerospace Corp., Space Sciences Laboratory, Los Angeles, Calif. 13 Warner and Swasey Observatory, Cleveland, Ohio 13 Universitaets-Sternwarte, Bonn, Federal Republic of Germany 13 Universidad de Puerto Rico, Rio Piedras 13 Universidad Central de Venezuela, Caracas 13 Universidad Autonoma de Madrid, Madrid, Spain 13 Univ. of Helsinki, Helsinki, Finland 13 Univ. Wuerzburg, Wuerzburg, Germany 13 Spetsial'naia Astrofizicheskaia Observatoriia, Zelenchukskaya, USSR 13 Rutgers Univ., Piscataway, NJ, US 13 Rothney Astrophysical Observatory, Calgary, Canada 13 Pic-du-Midi, Observatoire, Bagneres-de-Bigorre, Hautes-Pyrenees, France 13 Netherlands Foundation for Research in Astronomy, Dwingeloo 13 National Research Council of Canada, Ottawa, Ontario, Canada 13 NASA, Goddard Space Flight Center, Theoretical Studies Group, Greenbelt, Md. 13 NASA, Astrophysics Div., Washington, DC 13 NASA, Ames Research Center, Space Sciences Div., Moffett Field, CA 13 Mount John University Observatory, Christchurch, New Zealand 13 MPI fuer Radioastronomie, Bonn, Germany 13 Leander McCormick Observatory, Charlottesville, Va. 13 Iowa State University of Science and Technology, Ames, Iowa 13 Instituto Nacional de Tecnica Aeroespacial, Torrejon de Ardoz, Spain 13 Indiana University, Bloomington, IN, US 13 George Mason Univ., Fairfax, VA, US 13 Florida Institute of Technology, Melbourne 13 Embry-Riddle Aeronautical University, Daytona Beach, FL 13 Dipartimento di Astronomia, Universita di Padova, vicolo dell'Osservatorio 5, I-35122 Padova, Italy 13 Czech Academy of Sciences, Astronomical Inst., Ondrejov, Czech Republic 13 Copenhagen University Observatory, Tollose, Denmark 13 Copenhagen University Observatory, Denmark 13 China Center for Advanced Science and Technology, Beijing 13 CNRS/UPS, Toulouse, France 13 CNR, Gruppo Nazionale di Astronomia, Catania, Italy 13 Biurakanskaia Astrofizicheskaia Observatoriia, Yerevan, Armenian SSR 13 Berlin, Technische Universitaet, West Germany 13 Beijing Normal University, People's Republic of China 13 Astronomical Observatory, Nanjing, People's Republic of China 13 Astronomical Observatory, Belgrade, Yugoslavia 13 Arcetri, Osservatorio Astrofisico 12 University of Pittsburgh, Pittsburgh, PA, US 12 University of Oxford, Department of Physics, Nuclear Physics Laboratory, Keble Road, Oxford OX1 3RH, UK 12 University of Calgary, Calgary, Alberta, Canada 12 Universities Space Research Association, Washington 12 Universita di Firenze, Firenze, Italy 12 Univ. of Victoria, Victoria, BC, Canada 12 Univ. of Manchester Inst. of Science and Technology, United Kingdom 12 Tromso, Universitetet, Tromso, Norway 12 South Florida, University, Tampa, Fla. 12 South African Astronomical Observatory, PO Box 9, Observatory 7935, Cape Town, South Africa 12 Santa Maria, Universidade Federal, Brazil 12 Royal Australian Air Force Academy, Melbourne, Australia 12 Potchefstroom Univ., Potchefstroom, South Africa 12 Osservatorio Astronomico di Bologna, via Zamboni 33, I-40126 Bologna, Italy 12 New Brunswick, University, Fredericton, Canada 12 NSF, Div. of Astronomical Sciences, Washington, DC 12 NASA/Fermilab Astrophysics Center, Batavia 12 NASA. Jet Propulsion Lab., Pasadena, CA, US 12 NASA, Goddard Space Flight Center, Laboratory for Optical Astronomy, Greenbelt, Md. 12 Michigan State Univ., East Lansing, MI, US 12 Liege, Universite de l'Etat, Belgium 12 Lab. for Space Research, Utrecht, Netherlands 12 Iowa State University of Science and Technology, Ames, IA 12 Institute for Molecular Science, Okazaki, Japan 12 Institut za Fiziku, Belgrade, Yugoslavia 12 Inst. Astronomico e Geofisico, Sao Paulo, Brazil 12 Imperial College of Science, Technology, and Medicine, London, United Kingdom 12 Hawaii Univ., Honolulu, HI, US 12 Hartebeesthoek Radio Astronomy Observatory, Krugersdorp, Republic of South Africa 12 Frankfurt, Universitaet, Frankfurt am Main, West Germany 12 Department of Pure and Applied Physics, The Queen's University of Belfast, Belfast BT7 1NN, UK 12 Department of Physics and Astronomy, University of Wales, Cardiff CF2 3YB, UK 12 Centre d'Etudes et de Recherches de la Machine-Outil, Saint-Martin-d'Heres, France 12 Center for Particle Astrophysics, University of California, Berkeley, CA 94720, USA 12 CNR, Ist. di Fisica Cosmica, Milan, Italy 12 CEA, Centre d'Etudes de Bruyeres-le-Chatel, France 12 Beijing Observatory, Beijing, People's Republic of China 12 Astronomical Observatory, Kunming, People's Republic of China 12 Antwerpen, Rijksuniversitair Centrum, Antwerp, Belgium 12 Aerospace Corp., Los Angeles, Calif. 12 AN SSSR, Institut Iadernykh Issledovanii, Moscow, USSR 11 Van Vleck Observatory, Middletown, Conn. 11 University College, Campbell, Australia 11 Universite de Liege, Liege, Belgium 11 Universita di Bologna, Bologna, Italy 11 Universidad de Puerto Rico, Rio Piedras, PR 11 Univ. of Western Ontario, London, Ontario, Canada 11 Univ. of Tokyo, Mitaka, Tokyo, Japan 11 Univ. of Tokyo, Bunkyo, Tokyo, Japan 11 Univ. of Science and Technology of China, Hefei 11 Univ. of North Carolina, Chapel Hill, NC, US 11 Univ. of Lund, Lund, Sweden 11 Univ. of Calgary, Calgary, Alberta, Canada 11 The Queen's University of Belfast, Belfast, UK 11 Southern California, University, Los Angeles, Calif. 11 Science Research Council, Rutherford and Appleton Laboratories, Didcot, Oxon, England 11 Science Research Council, Appleton Laboratory, Abingdon, Oxon, England 11 San Francisco State University, CA 11 San Diego State Univ., CA 11 Research Centre for Theoretical Astrophysics, University of Sydney, NSW 2006, Australia 11 Physics Department, University of Durham, South Road, Durham DH1 3LE 11 Observatories of the Carnegie Inst. of Washington, Pasadena, CA, US 11 Observatoire de Strasbourg, Strasbourg, France 11 Natsionalna Astronomicheska Observatoriia, Sofia, Bulgaria 11 NASA, Marshall Space Flight Center, Space Sciences Laboratory, Huntsville, AL 11 Maria Mitchell Observatory, Nantucket, MA, US 11 London, University College, Mullard Space Science Laboratory, Dorking, Surrey, England 11 Lockheed Palo Alto Research Lab., Palo Alto, CA, US 11 Lawrence Berkeley Laboratory 11 Lausanne Univ., Chavannes-des-Bois, Switzerland 11 Konkoly Obszervatorium, Budapest, Hungary 11 Kiel, Universitaet, Institut fuer Theoretische Physik und Sternwarte, West Germany 11 Indiana Univ., Bloomington, IN, US 11 INPE, Sao Jose dos Campos, Brazil 11 IBM Almaden Research Center, San Jose, CA 11 Franklin Institute, Bartol Research Foundation, Newark, Del. 11 ETH-Zentrum, Zurich, Switzerland 11 Department of Physics, University of Durham, South Road, Durham DH1 3LE 11 Department of Physics and Astronomy, University of Leicester, Leicester LE1 7RH, UK 11 Darmstadt, Technische Hochschule, Darmstadt, West Germany 11 Crimean Astrophysical Observatory, Nauchny, Ukraine 11 Corralitos Observatory, Las Cruces, NM 11 Copenhagen University Observatory, Copenhagen, Denmark 11 CSIRO, Epping, Australia 11 CNR, Istituto di Fisica Cosmica e Informatica, Palermo, Italy 11 Bowling Green State University, Bowling Green, Ohio 11 Bhabha Atomic Research Centre, Srinagar, India 11 Australia Telescope National Facility, Epping, NSW, Australia 11 Atomic Energy Research Establishment, Culham Laboratory, Abingdon, Oxon, England 11 Astronomisches Rechen-Inst., Heidelberg, Germany 11 Aix-Marseille I, Universite, Marseille, France 11 Aichi University of Education, Kariya, Japan 10 Wyzsza Szkola Pedagogiczna, Opole, Poland 10 Vatican Observatory, Vatican City State 10 Vassar College Observatory, Poughkeepsie, NY 10 Utah, University, Salt Lake City, UT 10 University of California at San Diego, La Jolla, CA, US 10 Universitat Tuebingen, Tuebingen, Germany 10 Univ. of Tokyo, Tanashi, Tokyo, Japan 10 Univ. of Thessaloniki, Thessaloniki, Greece 10 Univ. of Leicester, Leicester, UK 10 Univ. of Bern, Bern, Switzerland 10 Univ. de Valencia, Valencia, Spain 10 Tokyo Metropolitan University, Japan 10 The Queen's Univ. of Belfast, Belfast, Northern Ireland 10 Tennessee State Univ., Nashville 10 State Astronomical Inst., Moscow, Russia 10 Specola Vaticana, Castel Gandolfo, Vatican City State 10 SRON, Laboratorium voor Ruimteonderzoek 10 Royal Observatory, Blackford Hill, Edinburgh EH93HJ 10 Rikkyo Univ., Toshima, Tokyo, Japan 10 Rhodes University, Grahamstown, Republic of South Africa 10 Queen's Univ. of Belfast, Belfast, N. Ireland, UK 10 Polish Academy of Sciences, Astronomical Center, Torun, Poland 10 Nicolaus Copernicus Astronomical Center, Warsaw, Poland 10 New South Wales Univ., Kensington, Australia 10 National Center for Atmospheric Research, Boulder, Colo. 10 National Astronomy and Ionosphere Center, Arecibo, P.R. 10 Muenchen, Univ., Munich, Germany 10 Missouri-Saint Louis, University, Saint Louis 10 Lille I, Universite, Villeneuve-d'Ascq, Nord, France 10 Leiden Southern Station, Broederstroom, Republic of South Africa 10 Kyoto Univ., Sakyo, Kyoto, Japan 10 Kiel, Universitaet, Institut fuer theoretische Physik und Sternwarte, Kiel, West Germany 10 Kernforschungszentrum Karlsruhe GmbH, Karlsruhe, West Germany 10 Istituto Universitario Navale, Naples, Italy 10 Iowa State Univ. of Science and Technology, Ames 10 International Centre for Relativistic Astrophysics, Rome, Italy 10 International Centre for Relativistic Astrophysics 10 International Center for Theoretical Physics, Trieste, Italy 10 International Center for Relativistic Astrophysics, Rome, Italy 10 Instituto de Pesquisas Espaciais, Sao Jose dos Campos, Sao Paulo, Brazil 10 Institute of Space and Astronautical Science, 3-1-1 Yoshinodai, Sagamihara, Kanagawa 229, Japan 10 Institute of Physical and Chemical Research, Saitama, Japan 10 Institute of Astronomy, University of Cambridge, Madingley Road, Cambridge CB3 0HA 10 Inst. of Physical and Chemical Research, Wako, Japan 10 Inst. d'Astrophysique Spatiale, Orsay, France 10 Franklin Institute, Bartol Research Foundation, Swarthmore, Pa. 10 Flower and Cook Observatory, Philadelphia, Pa. 10 Division of Physical Sciences, University of Hertfordshire, College Lane, Hatfield, Herts AL10 9AB, UK 10 Department of Physics, Keele University, Keele, Staffordshire ST5 5BG 10 Department of Physics and Astronomy, University of Wales College of Cardiff, PO Box 913, Cardiff CF2 3YB, UK 10 Department of Physics and Astronomy, Northwestern University, Evanston, IL 60208, USA 10 Department of Astronomy, University of Cape Town, Rondebosch 7700, Cape, South Africa 10 Cote d'Azur, Observatoire, Nice, France 10 Cooperative Institute for Research in Environmental Sciences, Boulder, CO 10 Commissariat al'Energie Atomique, Service d'Astrophysique, Gif-sur-Yvette, Essonne, France 10 Center for High-Energy Astrophysics, Netherlands 10 Cataluna, Universidad Politecnica, Barcelona, Spain 10 Brigham Young University, Provo, UT, US 10 Brandeis Univ., Waltham, MA, US 10 Astrophysikalisches Inst. 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Joseph Fourier, Grenoble, France 9 U.S. Navy, Center for Advanced Space Sensing, Washington, DC 9 U.S. Naval Academy, Annapolis, MD 9 Tennessee State University, Nashville, TN, US 9 Sternberg Astronomical Institute, Moscow, Russia 9 Southwest Research Institute, San Antonio, TX 9 Southern California, University, Los Angeles 9 School of Physics, University of Sydney, NSW 2006, Australia 9 San Diego State University, San Diego, Calif. 9 Saint Mary's Univ., Halifax, Nova Scotia, Canada 9 Sachs/Freeman Associates, Inc., Landover, MD 9 Royal Greenwich Observatory, Santa Cruz de La Palma, Spain 9 Radio Astronomy Observatory, Ann Arbor, Mich. 9 Observatorio Astronomico, Santiago de Compostela, Spain 9 Observatorio Astronomico Nacional, Santiago, Chile 9 Observatoire du Pic-du-Midi, Bagneres-de-Bigorre, France 9 Nuffield Radio Astronomy Laboratories, University of Manchester, Jodrell Bank, Macclesfield, Cheshire SK11 9DL 9 North Carolina, University, Chapel Hill, NC 9 Niels Bohr Inst., Copenhagen, Denmark 9 NSF Center for Particle Astrophysics, US 9 Middle East Technical Univ., Ankara, Turkey 9 McDonald Observatory, Texas Univ., Austin, TX, US 9 Leiden Observatory, Leiden, The Netherlands 9 Lab. for Space Research, Groningen, Netherlands 9 Kapteyn Sterrenwacht, Roden, Netherlands 9 Joint Inst. for Lab. Astrophysics 9 Ist. Nazionale di Fisica Nucleare, Italy 9 Interferometrics, Inc., Vienna, VA 9 Inter-Univ. Centre for Astronomy and Astrophysics, Poona, India 9 Instituto Astronomico e Geofisico, Sao Paulo, Brazil 9 Institute for Astronomy, University of Edinburgh, Blackford Hill, Edinburgh EH9 3HJ, UK 9 Harvard College Observatory, Cambridge, MA 9 Edinburgh, Royal Observatory, U.K. Schmidt Telescope Unit, Coonabarabran, New South Wales, Australia 9 Department of Physics and Astronomy, University of Wales College of Cardiff, PO Box 913, Cardiff CF2 3YB 9 Department of Physics and Astronomy, Johns Hopkins University, 3400 N. Charles Street, Baltimore, MD 21218, USA 9 Department of Astronomy, University of Texas, Austin, TX 78712, USA 9 DAPNIA, Gif-sur-Yvette, France 9 Commissariat a l'Energie Atomique, Section d'Astrophysique, Gif-sur-Yvette, Essonne, France 9 Clyde W. Tombaugh Observatory, Lawrence, KS 9 Chalmers Tekniska Hogskola, Goteborg, Sweden 9 Ceskoslovenska Akademie Ved, Astronomicky Ustav, Prague, Czechoslovakia 9 Centre d'Etudes et de Recherches Geodynamiques et Astronomiques, Grasse, France 9 California Association for Research in Astronomy, Kamuela, HI, US 9 CNRS, Institut d'Astrophysique Spatiale, Verrieres-le-Buisson, France 9 CEN de Saclay, Gif-sur-Yvette, France 9 Bonn, Univ., Sternwarte, Germany 9 Australian Defence Force Academy, Campbell, Australia 9 Astronomy Unit, Queen Mary and Westfield College, University of London, Mile End Road, London E1 4NS, UK 9 Astronomy Centre, University of Sussex, Falmer, Brighton BN1 9QH 9 Astrofizicheskaia Observatoriia, Tartu, Estonian SSR 8 Williams College, Williamstown, MA 8 Vassar College, Poughkeepsie, NY 8 Vanderbilt Univ., Nashville, TN 8 University of Victoria, Victoria, BC, Canada 8 University of Maryland, College Park, Maryland, US 8 University of Manchester, NRAL, Jodrell Bank, Macclesfield, Cheshire SK11 9DL, UK 8 University of Colorado, Boulder, Colorado, US 8 University of Birmingham, Edgbaston, Birmingham, UK 8 University of Alabama at Huntsville, Huntsville, AL, US 8 Universities Space Research Association, Columbia, MD 8 Universite Paris-Sud, Orsay, France 8 Universidade Mackenzie, Sao Paulo, Brazil 8 Universidad de los Andes, Merida, Venezuela 8 Univ. of Toronto, Ontario, Canada 8 Univ. of Pittsburgh, Pittsburgh, PA, US 8 Univ. of New Mexico, Albuquerque, NM, US 8 Univ. of Hong Kong, Hong Kong 8 Univ. of California at Santa Cruz, Santa Cruz, CA, US 8 Univ. de Cantabria, Santander, Spain 8 Univ. de Barcelona, Barcelona, Spain 8 Tartuskaia Astrofizicheskaia Observatoriia, Toravere, Estonian SSR 8 Steward Observatory, University of Arizona, Tucson, AZ 85721, USA 8 Sterrenkundig Observatorium, Ghent, Belgium 8 Sternwarte der Universitaet Bonn, Bonn, Germany 8 Space Telescope European Coordinating Facility, Garching, Germany 8 Space Research Inst., Moscow, Russia 8 South African Astronomical Observatory, PO Box 9, 7935 Observatory, South Africa 8 Sonnenobservatorium Kanzelhoehe, Sattendorf, Austria 8 Societat Catalana de Fisica, Spain 8 San Diego State University, San Diego, CA, US 8 SISSA/ISAS, Trieste, Italy 8 Rosemary Hill Observatory, Gainesville, FL 8 Raman Research Institute, Bangalore 560080, India 8 Queen Mary and Westfield Coll., London Univ., London, UK 8 Pic du Midi et Toulouse, Observatoires, Toulouse, France 8 Physics Department, University of Tasmania, GPO Box 252C, Hobart, TAS 7001, Australia 8 Palomar Observatory, California Inst. of Tech., Pasadena, CA, US 8 Owens Valley Radio Observatory 8 Observatorio del Roque de los Muchachos, Santa Cruz de la Palma, Spain 8 Nuffield Radio Astronomy Laboratories, University of Manchester, Jodrell Bank, Macclesfield, Cheshire SK11 9DL, UK 8 North Carolina State Univ., Raleigh 8 Nicolaus Copernicus Astronomical Center, Bartycka 18, 00-716 Warsaw, Poland 8 New Mexico State Univ., Las Cruces 8 New Mexico Institute of Mining and Technology, Socorro, NM 8 New Jersey Institute of Technology, Newark 8 Nauchno-Issledovatel'skii Radiofizicheskii Institut, Gorki, USSR 8 National Research Council of Canada, Victoria, BC, Canada 8 National Bureau of Standards, Quantum Physics Div., Boulder, Colo. 8 NRAO, Charlottesville, VA, US 8 NASA, Marshall Space Flight Center 8 Mullard Space Science Laboratory, University College London, Holmbury St Mary, Dorking, Surrey RH5 6NT 8 Mt Stromlo and Siding Spring Observatories, Australian National University, Weston, ACT 2611, Australia 8 Monterey Institute for Research in Astronomy, CA 8 Minnesota Univ., Minneapolis, MN, US 8 Ministerio de Educacion, Instituto Isaac Newton, Santiago, Chile 8 Michigan State Univ., East Lansing 8 Mathematical Science Consultants, Inc., Greenbelt, MD 8 MIT Haystack Observatory, Westford, MA, US 8 Lockheed Missiles and Space Co., Inc., Palo Alto, Calif. 8 Leuven, Katholieke Univ., Heverlee, Belgium 8 Leiden Observatory, PO Box 9513, 2300 RA Leiden, The Netherlands 8 La Plata, Univ. 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Astrophysical Observatory, Penticton, Canada 6 Department of Physics, University of Sheffield, The Hicks Building, Hounsfield Road, Sheffield S3 7RH, UK 6 Department of Physics, The Citadel, Charleston, SC 29409, USA 6 Department of Physics, Science Laboratories, South Road, Durham DH1 3LE, UK 6 Department of Physics and Astronomy, University of Manchester, Schuster Laboratory, Oxford Road, Manchester M13 9PL, UK 6 Department of Physics and Astronomy, University of Manchester, Schuster Laboratory, Oxford Road, Manchester M13 9PL 6 Department of Physical Sciences, University of Hertfordshire, College Lane, Hatfield, Herts AL10 9AB 6 Department of Applied Mathematics and Theoretical Physics, University of Cambridge, Cambridge CB3 9EW 6 Computer Sciences Corp., Astronomy Dept., Silver Spring, MD 6 Communications Research Laboratory, Tokyo, Japan 6 Commonwealth Scientific and Industrial Research Organization, Div. of Chemical Physics, Clayton, Victoria, Australia 6 Clark Lake Radio Observatory, Borrego Springs, Calif. 6 City Polytechnic of Hong Kong, Kowloon 6 Charles Univ., Prague, Czech Republic 6 Centre for High Energy Astrophysics, Netherlands 6 Centre d'Etudes et de Recherches de la Machine-Outil, Saint-Martin-d'Heres, Isere, France 6 Centre d'Etudes et de Recherches Geodynamiques et Astronomiques, Saint-Vallier-de-Thiey, Alpes-Maritimes, France 6 Catania, Osservatorio Astrofisico 6 Carnegie Observatories, 813 Santa Barbara Street, Pasadena, CA 91101, USA 6 CNRS, Centre de Spectrometrie Nucleaire et de Spectrometrie de Masse, Orsay, France 6 CNR, Istituto di Fisica Cosmica ed Applicazioni dell'Informatica, Palermo, Italy 6 CNR, Istituto di Fisica Cosmica 6 CNR, Ist. di Fisica Cosmica con Applicazioni all'Informatica, Palermo, Italy 6 CNR, Centro per l'Astronomia Infrarossa, Florence, Italy 6 Byurakan Astrophysical Observatory, Armenia 6 Bowling Green State University, Bowling Green, OH 6 Blackett Laboratory, Imperial College, London SW7 2BZ, UK 6 Biurakanskaia Astrofizicheskaia Observatoriia, Byurakan, Armenian SSR 6 Beograd, Astronomska Opservatorija, Belgrade, Yugoslavia 6 Ball Brothers Research Corp., Boulder, Colo. 6 Astrophysics, Nuclear Physics Laboratory, Keble Road, Oxford OX1 3RH 6 Astronomy Unit, School of Mathematical Sciences, Queen Mary & Westfield College, Mile End Road, London E1 4NS, UK 6 Astronomy Group, University of Leicester, Leicester LE1 7RH, UK 6 Astronomy Centre, University of Sussex, Falmer, Brighton BN1 9QH, UK 6 Astronomy Centre, School of Mathematical and Physical Sciences, University of Sussex, Falmer, Brighton BN1 9QH 6 Astronomicheskaia Observatoriia, Leningrad, USSR 6 Astronomical Institute `Anton Pannekoek', University of Amsterdam and Center for High Energy Astrophysics, Kruislaan 403, NL-1098 SJ Amsterdam, the Netherlands 6 Asiago Astrophysical Observatory, Italy 6 Armagh Observatory, College Hill, Armagh BT61 9DG 6 Arecibo Ionospheric Observatory, Arecibo, P.R. 6 Arcetri Astrophysical Observatory, Florence, Italy 6 Aerospace Corp., Space Sciences Laboratory, Los Angeles 6 Aerospace Corp., El Segundo, Calif. 6 Academy of Sciences of Czech Republic, Ondrejov, Czech Republic 6 AN SSSR, Institut Zemnogo Magnetizma, Ionosfery i Rasprostraneniia Radiovoln, Troitsk, USSR 5 York Univ., Toronto, Canada 5 Yamanashi Univ., Takeda, Japan 5 Wroclaw, Uniwersytet, Obserwatorium, Poland 5 Western Kentucky University, Bowling Green, Ky. 5 Western Kentucky University, Bowling Green, KY 5 Western Australia, University, Nedlands, Australia 5 Wellesley College, Wellesley, Mass. 5 Warszawa, Uniwersytet, Warsaw, Poland 5 University of Western Ontario, London, Ontario, Canada 5 University of Tokyo, Mitake-mura, Kiso-gun, Japan 5 University of Southampton, Department of Physics, Highfield, Southampton SO17 1BJ, UK 5 University of Notre Dame, Notre Dame, IN, US 5 University of Cape Town, Cape Town, South Africa 5 University of California at Los Angeles, Los Angeles, CA, US 5 Universitat de les Illes Balears, Palma de Mallorca, Spain 5 Universitat Heidelberg, Heidelberg, Germany 5 Universidade Federal Fluminense, Niteroi, Brazil 5 Univ. pr., Moscow, Russia 5 Univ. of Toronto, Toronto, ON, Canada 5 Univ. of Toronto, Mississauga, Ontario, Canada 5 Univ. of Tokyo, Meguro-ku, Tokyo, Japan 5 Univ. of Southampton, Southampton, UK 5 Univ. of Pennsylvania, Philadelphia, PA, US 5 Univ. of Montreal, Montreal, Quebec, Canada 5 Univ. of Manchester, Cheshire, UK 5 Univ. of Electro-Communications, Tokyo, Japan 5 Univ. of British Columbia, Vancouver, Canada 5 Univ. of British Columbia, BC, Canada 5 Univ. di Bologna, Bologna, Italy 5 Univ. de les Illes Balears, Palma de Mallorca, Spain 5 Univ. Nacional de La Plata, La Plata, Argentina 5 Univ. Heidelberg, Heidelberg, Germany 5 USAF, Phillips Lab., Hanscom AFB, MA 5 USAF, Geophysics Laboratory, Sunspot, NM 5 USAF, Geophysics Laboratory 5 U.S. Merchant Marine Academy, Kings Point, NY 5 Turku Univ. Observatory, Piikkio, Finland 5 Trenton State College, Trenton, N.J. 5 Tokyo Metropolitan Univ., Tokyo, Japan 5 Tokyo Gakugei University, Koganei, Japan 5 Theoretical Physics, Department of Physics, 1 Keble Road, Oxford OX1 3NP 5 The Univ. of Tokyo, Tokyo, Japan 5 Tasmania Univ., Hobart, Australia 5 Systems and Applied Sciences Corp., Hyattsville, MD 5 Stichting Astronomisch Onderzoek in Nederland, Amsterdam, Netherlands 5 Stephen F. Austin State University, Nacogdoches, TX 5 State Univ. of New York, Stony Brook, NY, US 5 Special Astrophysical Observatory, Zelenchukskaya, Russia 5 South Alabama, University, Mobile, AL 5 South African Astronomical Observatory, Cape Town, South Africa 5 Sonnenobservatorium Einsteinturm, Potsdam, East Germany 5 Solar Physics Research Corp., Tucson, AZ 5 Sibirskii IZMIRAN, Irkutsk, USSR 5 Severn Communications Corp., Severna Park, MD 5 Science Research Council, Appleton Laboratory, Slough, Bucks., England 5 Science Applications International Corp., San Diego, CA 5 School of Physics, University College, Australian Defence Force Academy, The University of New South Wales, Canberra, 2600, ACT, Australia 5 School of Physics and Astronomy, University of St Andrews, North Haugh, St Andrews, Fife KY16 9SS 5 School of Physics and Astronomy, University of Birmingham, Edgbaston, Birmingham B15 2TT 5 Sandia Laboratories, Albuquerque, N. Mex. 5 Saint Patrick's College, Maynooth, Republic of Ireland 5 Saha Institute of Nuclear Physics, Calcutta, India 5 Sachs/Freeman Associates, Bowie, MD 5 SETI Institute, Mountain View, CA 5 Rutherford Appleton Laboratory, Didcot 5 Russian Academy of Sciences, Physical-Technical Inst., St. Petersburg, Russia 5 Russian Academy of Sciences, Inst. of Space Research, Moscow, Russia 5 Ruhr-Univ. Bochum, Bochum, Germany 5 Royal Greenwich Observatory, Madingley Road, Cambridge CB30EZ 5 Rhodes College, Memphis, TN, US 5 Research Centre for Theoretical Astrophysics, School of Physics A28, University of Sydney, NSW 2006, Australia 5 Raman Research Institute 5 Radiosterrewacht, Dwingeloo, Netherlands 5 Porto, Universidade, Porto, Portugal 5 Pic-du-Midi, Observatoire, Bagneres-de-Bigorre, France 5 Phillips Laboratory, Hanscom AFB, MA, US 5 Paris VII, Universite, Meudon, France 5 Palomar Observatory, California Institute of Technology, Mail Stop 105-24, Pasadena, CA 91125, USA 5 Palermo, Universita and CNR, Gruppi Italiani di Fisica Cosmica, Palermo, Italy 5 Owens Valley Radio Observatory, Pasadena 5 Osservatorio Astronomico, via Zamboni 33, I-40126 Bologna, Italy 5 Osservatorio Astronomico, Vicolo dell'Osservatorio 5, I-35122 Padova, Italy 5 Osservatorio Astronomico di Brera, via Brera 28, 20121 Milano, Italy 5 Osservatorio Astronomico di Brera, Via Brera 28, I-20121 Milano, Italy 5 Osservatorio Astrofisico di Catania, Catania, Italy 5 Osaka Univ., Toyonaka, Osaka, Japan 5 Observatorium Hoher List, Bonn, West Germany 5 Observatorio Astronomico de Cerro Calan, Santiago, Chile 5 Observatorio Astronomico Nacional, Granada, Spain 5 Observatoire de Paris-Meudon, 92195 Meudon Cedex, France 5 Observatoire de Marseille, 2 Place Le Verrier, F-13248 Marseille Cedex 4, France 5 Observatoire Astronomique du Mont Megantic 5 Nuffield Radio Astronomy Laboratories, Cheshire, UK 5 Nijmegen, Katholieke Universiteit, Nijmegen 5 Nijmegen, Katholieke Universiteit, Netherlands 5 Newcastle-upon-Tyne, University, Newcastle-upon-Tyne, England 5 New Mexico Institute of Mining and Technology 5 National Radio Observatory, Socorro, NM, US 5 National Radio Astronomy Observatory, PO Box 0, Socorro, NM 87801, USA 5 National Laboratory for High Energy Physics, Tsukuba, Japan 5 National Lab. for High Energy Physics, Tsukuba, Japan 5 National Institute of Standards and Technology, Gaithersburg, MD, US 5 National Bureau of Standards, Molecular Spectroscopy Div., Washington, DC 5 National Bureau of Standards, Boulder, Colo. 5 National Air and Space Museum, Washington 5 Nanjing, University, People's Republic of China 5 NOAA, Space Environment Lab., Boulder, CO 5 NASA. USRA, STX Corp., Greenbelt, MD, US 5 NASA. Fermilab Astrophysics Center, Batavia, IL, US 5 NASA, Ames Research Center, Space Sciences Div., Moffett Field 5 NASA, Ames Research Center, Space Science Div., Moffett Field, Calif. 5 Mount John Observatory, Christchurch, New Zealand 5 Minas Gerais, Universidade Federal, Belo Horizonte, Brazil 5 Max-Planck-Institut fur extraterrestrische Physik, Giessenbachstrasse, D-85740 Garching, Germany 5 Max-Planck-Institut fur Astrophysik, Karl-Schwarzschild-Strasse 1, D-85740 Garching, Germany 5 Max-Planck-Institut fuer Aeronomie, Lindau ueber Northeim, West Germany 5 Max-Planck-Inst. fur extraterrestrische Physik, Giessenbachstrasse, German 5 Max-Planck Institute, Garching, Germany 5 Max Planck Society, Jena, Germany 5 Massachusetts Institute of Technology, Cambridge, Massachusetts, US 5 Marseille, Observatoire, Marseille 5 MPI fuer Extraterrestrische Physik, Munchen, Germany 5 MIT, Lincoln Laboratory, Lexington, Mass. 5 Lund Institute of Technology, Lund, Sweden 5 Lunar and Planetary Institute, Houston, TX 5 London, University, Observatory, London, England 5 Liege, Institut d'Astrophysique, Cointe-Ougree, Belgium 5 Leiden Observatory, PO Box 9513, 2300 RA, Leiden, The Netherlands 5 Lawrence Berkeley Lab., Berkeley 5 Laboratory for Space Research, Groningen, Netherlands 5 Laboratory for High Energy Astrophysics, Code 660, NASA/Goddard Space Flight Center, Greenbelt, MD 20771, USA 5 Laboratoire d'Astrophsiqure de Toulouse, Toulouse, France 5 Korea Astronomy Observatory, Daejon, Korea 5 Kokugakuin University, Tokyo, Japan 5 Kiepenheuer Institut fuer Sonnenphysik, Freiburg im Breisgau, West Germany 5 Kapteyn Laboratorium, Groningen, Netherlands 5 Joint Astronomy Centre, 660 N. A`ohoku Place, University Park, Hilo, HI 96720, USA 5 Jamieson Science and Engineering, Inc., Scotts Valley 5 Jadavpur Univ., Calcutta, India 5 Istituto e Osservatorio Astronomico di Palermo, Palermo, Italy 5 Istituto di Astrofisica Spaziale (CNR), Frascati, Italy 5 Istituto TESRE/CNR, Bologna, Italy 5 International Statistics and Research Corp., Brentwood Bay, Canada 5 International Centre for Theoretical Physics 5 Instytut Badan Jadrowych, Lodz, Poland 5 Instituto de Fisica de Cantabria (Consejo Superior de Investigaciones Cientificas - Universidad de Cantabria), 39005 Santander, Spain 5 Instituto de Astronomia y Fisica del Espacio, Buenos Aires 5 Instituto Nacional de Tecnica Aeroespacial, Madrid, Spain 5 Instituto Isaac Newton, Santiago, Chile 5 Instituto Argentino de Radioastronomia, Buenos Aires, Argentina 5 Institute of Astronomy, The Observatories, Madingley Road, Cambridge CB3 0HA 5 Institute for Astronomy, University of Edinburgh, Royal Observatory, Blackford Hill, Edinburgh EH9 3HJ, UK 5 Institut fur Astronomie, Universitat Wien, Turkenschanzstrasse 17, A-1180 Wien, Austria 5 Institut fuer Kosmosforschung, Berlin, Federal Republic of Germany 5 Institut de Radioastronomie Millimetrique 5 Institut d'Estudis Catalans 5 Inst. de Estudios Avanzados en Fisica Moderna y Biologia Molecular, Santander, Spain 5 Imperial College of Science, Technology and Medicine, Blackett Laboratory, Prince Consort Road, London SW7 2BZ 5 IBM Thomas J. Watson Research Center, Yorktown Heights 5 Hvar, Opservatorija, Zagreb, Yugoslavia 5 Helsinki University of Technology, Kylmala, Finland 5 Helsinki Univ. of Technology, Espoo, Finland 5 Hatfield Polytechnic, Hatfield, Herts., England 5 Harvard-Smithsonian, Cambridge, MA, US 5 Hampshire College, Amherst, Mass. 5 HAO/NCAR, Boulder, CO, US 5 Grenoble I, Universite, Observatoire, France 5 Glasgow, University, Observatory, Glasgow, Scotland 5 Fred Lawrence Whipple Observatory, Amado, AZ 5 Franklin and Marshall College, Lancaster, PA, US 5 Foundation for Research and Technology-Hellas, Heraklion, Greece 5 Florida Univ., Gainesville, FL, US 5 Fernbank Science Center, Atlanta, Ga. 5 Fermi National Accelerator Laboratory, Batavia, IL, US 5 Edinburgh, Royal Observatory, U.K. Schmidt Telescope Unit, Coonabarabran, Australia 5 Edinburgh, Royal Observatory, Coonabarabran, New South Wales, Australia 5 ESA, Space Telescope European Coordinating Facility, Garching, Federal Republic of Germany 5 ESA, Satellite Tracking Station, Madrid, Spain 5 ESA, European Space Research and Technology Centre, Noordwijk 5 E. O. Hulburt Center for Space Research, NRL, Washington, DC, US 5 Dominion Astrophysical Observatory, Victoria 5 Division of Physical Sciences, University of Hertfordshire, Hatfield, Herts AL10 9AB 5 Division of Physical Sciences, University of Hertfordshire, College Lane, Hatfield, Herts AL10 9AB 5 Dipartimento di Astronomia, Universita di Bologna, via Zamboni 33, I-40126 Bologna, Italy 5 Dipartimento di Astronomia, Universita di Bologna, via Zamboni 33, Bologna 40126, Italy 5 Deutsche Akademie der Wissenschaften, Zentralinstitut fuer Astrophysik, Potsdam, East Germany 5 Department of Pure and Applied Physics, Queen's University, Belfast BT7 1NN, UK 5 Department of Pure and Applied Physics, Queen's University, Belfast BT7 1NN 5 Department of Physics, University of Padova, Via Marzolo 8, 35131 Padova, Italy 5 Department of Physics, The University, Southampton SO17 1BJ 5 Department of Physics, Nuclear and Astrophysics Laboratory, Keble Road, University of Oxford, Oxford OX1 3RH 5 Department of Physics, Keele University, Keele ST5 5BG, UK 5 Department of Physics, Astrophysics, University of Oxford, Keble Road, Oxford OX1 3RH, UK 5 Department of Physics and Astronomy, University of Kansas, Lawrence, KS 66045, USA 5 Department of Physics and Astronomy, Leicester University, University Road, Leicester LE1 7RH 5 Department of Applied Mathematics and Theoretical Physics, The Queen's University of Belfast, Belfast BT7 1NN 5 Departamento de Astronomia, IF-UFRGS, CP 15051, CEP 91501-970, Porto Alegre, RS, Brasil 5 Copernicus Astronomical Center, Bartycka 18, 00-716 Warsaw, Poland 5 Copenhagen, University, Observatory, Tollose, Denmark 5 Copenhagen, University, Copenhagen, Denmark 5 Copenhagen, University Observatory, Tollose, Denmark 5 Consejo Superior de Investogaciones Cientificas, Granada, Spain 5 Commissariat a l'Energie Atomique, Centre d'Etudes de Limeil, Villeneuve-Saint-Georges, Val-de-Marne 5 Comision Nacional de Investigacion del Espacio, Torrejon de Ardoz, Spain 5 College of William and Mary, Williamsburg, Va. 5 Citta Universitaria, Catania, Italy 5 Charles University, Prague, Czechoslovakia 5 Centro di Studi sui Sistemi, Turin, Italy 5 Centre for Astrophysics, University of Central Lancashire, Preston PR1 2HE 5 Catholic Univ. of America, Washington, DC, US 5 Catholic Univ. of America, Washington 5 California, University, Riverside, Calif. 5 California, University, Berkeley and Santa Barbara 5 California Institute of Technology, Jet Propulsion Laboratory, Space Sciences Div., Pasadena, Calif. 5 California Institute of Technology, Jet Propulsion Laboratory, Earth and Space Sciences Div., Pasadena, Calif. 5 CSIRO, Epping, NSW, Australia 5 CONICET, Instituto de Astronomia y Fisica del Espacio, Buenos Aires 5 CONICET, Inst. de Astronomia y Fisica del Espacio, Buenos Aires, Argentina 5 CNRS, Centre de Physique Theorique, Marseille, France 5 CNR, Laboratorio per il Plasma nello Spazio, Frascati, Italy 5 CNR, Laboratorio di Fisica Cosmica e Tecnologie Relative, Palermo, Italy 5 CNR, Laboratorio di Fisica Cosmica e Technologie Relative, Milan, Italy 5 CNR, Istituto di Studio e Tecnologie sulle Radiazioni Extraterrestri, Bologna, Italy 5 CNR, Istituto di Fisica Cosmica, Milan 5 CNR, Istituto di Cosmogeofisica 5 CNR, Ist. di Tecnologie e Studio delle Radiazioni Extraterrestri, Bologna, Italy 5 CNR, Ist. di Fisica Cosmica, Milan 5 CNR, Gruppo Nazionale di Astronomia, Florence, Italy 5 CNR, Centro per l'Astronomia Infrarossa e lo Studio del Mezzo Interstellare, Florence, Italy 5 CNR, Centro di Astronomia Infrarossa, Florence, Italy 5 CNPq, Laboratorio Nacional de Astrofisica, Itajuba, Brazil 5 C.E. Kenneth Mees Observatory, Rochester, NY 5 Boyden Observatory, Bloemfontein, Republic of South Africa 5 Bordeaux I, Universite, Talence, Gironde, France 5 Bologna, Osservatorio Astronomico 5 Bochum, Ruhr-Universitaet 5 Blackett Laboratory, Imperial College, Prince Consort Road, London SW7 2BZ, UK 5 Berlin, Technische Univ. 5 Benedictine College, Atchison, KS 5 Atmospheric and Environmental Research, Inc., Cambridge, Mass. 5 Athens, National Capodistrian University, Athens, Greece 5 Astrophysikalisches Institut Postsdam, An der Sternwarte 16, D-14482, Potsdam, Germany 5 Astrophysics Group, Liverpool John Moores University, Byrom Street, Liverpool L3 3AF, UK 5 Astronomy Unit, School of Mathematical Sciences, Queen Mary and Westfield College, Mile End Road, London E1 4NS, UK 5 Astronomy Group, Leicester University, University Road, Leicester LE1 7RH 5 Astronomy Department, University of Cape Town, Private Bag, Rondebosch, 7700, South Africa 5 Astronomisches Rechen-Institut, Monchhofstrasse 12-14, D-69120 Heidelberg, Germany 5 Astronomical Inst. 'Anton Pannekoek', Amsterdam, Netherlands 5 Asiago, Osservatorio Astrofisico, Italy 5 Armagh Observatory, College Hill, Armagh BT61 9DG, UK 5 Argonne National Laboratory, Argonne, Ill. 5 Ankara University Observatory, Turkey 5 Aerospace Corp., Electronics Research Laboratory, Los Angeles, Calif. 5 Academy of Sciences of the Czech Republic, Ondrejov, Czech Republic 5 AN LSSR, Institut Fiziki, Vilnius, Lithuanian SSR 4 Zulia, Universidad, Maracaibo, Venezuela 4 Yunnan Observatory, Kunming, Yunnan, China 4 Yonsei University Observatory, Seoul, Republic of Korea 4 X-Ray Astronomy Group, Department of Physics and Astronomy, University of Leicester, Leicester LE1 7RH 4 Wyzsza Szkola Pedagogiczna, Rzeszow, Poland 4 Wise Observatory, Tel Aviv University, Ramat Aviv, Tel Aviv 69978, Israel 4 Wise Observatory, Sackler Faculty of Exact Sciences, Tel Aviv University, Tel Aviv 69978, Israel 4 Washington Univ., Saint Louis, MO, US 4 Warszawa, Uniwersytet, Obserwatorium Astronomiczne, Warsaw, Poland 4 Warsaw University Observatory, Al. Ujazdowskie ~4, 00-478 Warsaw, Poland 4 Warsaw Univ., Warsaw, Poland 4 Warsaw Univ. 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Pierre et Marie Curie, Paris, France 4 Univ. Laval, Sainte-Foy, Quebec, Canada 4 Univ. La Sapienza, Rome, Italy 4 Univ. Hamburg, Gojenbergsweg, Hamburg, Germany 4 Univ. College London, Surrey, UK 4 Univ. Basel, Basel, Switzerland 4 USAF, Geophysics Laboratory, Hanscom AFB 4 UNAM, Mexico City, Mexico 4 UCSB, Santa Barbara, CA, US 4 U.S. Air Force Academy, Colorado Springs, CO 4 Toronto Univ., Mississauga, Canada 4 Torino, Osservatorio Astronomico, Pino Torinese 4 Tokyo Gakugei Univ., Tokyo, Japan 4 Tianjin Normal University, People's Republic of China 4 Theoretical Astrophysics Center, Juliane Maries Vej 30, DK-2100 Copenhagen O, Denmark 4 The University of Tokyo, Tokyo, Japan 4 The Institute of Physical and Chemical Research, Saitama, Japan 4 The Director, University of Manchester, Nuffield Radio Astronomy Laboratories, Jodrell Bank, Macclesfield, Cheshire SK11 9DL 4 The Citadel, Charleston, SC, US 4 The Australian National University Astrophysical Theory Centre, School of Mathematical Sciences, Canberra, ACT 0200, Australia 4 Texas Christian University, Fort Worth 4 Teoretisk Astrofysik Center, Danmarks Grundforskningsfond, Institut for Fysik og Astronomi, Aarhus Universitet, DK-8000 Aarhus C, Denmark 4 Tel Aviv Univ., Ramat Aviv, Israel 4 Systems and Applied Sciences Corp., Riverdale, Md. 4 Strada dell'Osservatorio, Torinese, Italy 4 Sterrewacht Sonnenborgh 4 Sterrewacht Leiden, Postbus 9513, 2300 RA Leiden, Netherlands 4 State Institute of Theoretical Physics and Astronomy, Gostauto 12, Vilnius 2600, Lithuania 4 State Astronomical Institute, Moscow, Russia 4 Special Astrophysical Observatory, Russian Academy of Sciences, Niznhny Arkhyz, Karachai-Cherkess Republic, 357147, Russia 4 Southwestern Louisiana, University, Lafayette, La. 4 Southampton University, Southampton, England 4 South African Astronomical Observatory, South Africa 4 South African Astronomical Observatory, PO Box 9, Observatory, 7935 South Africa 4 Smith College, Northampton, Mass. 4 Smith College, Northampton, MA, US 4 Slovenska Akademia Vied, Astronomicky Ustav, Tatranska Lomnica, Czechoslovakia 4 Sektion Physik, Ludwig-Maximilians-Universitat, Theresienstr. 37, D-80333 Munchen, Germany 4 Science Research Council, Rutherford and Appleton Laboratories, Slough, Berks., England 4 Science Research Council, Appleton Laboratory, Madrid, Spain 4 Science Applications International Corp., Planetary Science Institute, Tucson, AZ 4 School of Physics, University of New South Wales, PO Box 1, Kensington NSW 2033, Australia 4 School of Physics, University of Melbourne, Parkville, Victoria 3052, Australia 4 School of Physics and Astronomy and the Wise Observatory, The Raymond and Beverley Sackler Institute of Exact Sciences, Tel Aviv University, Tel Aviv 69978, Israel 4 School of Cosmic Physics, Dublin, Ireland 4 School of Chemistry, University of Bristol, Cantock's Close, Bristol BS8 1TS 4 School of Chemistry, University of Bristol, Bristol BS8 1TS, UK 4 School of Chemical and Physical Sciences, Liverpool John Moores University, Byrom Street, Liverpool L3 3AF 4 San Francisco State University, San Francisco, CA 4 Saint Mary's Univ., Halifax, Canada 4 Saint Andrews, University, Observatory, Scotland 4 SRON-Utrecht, Utrecht, Netherlands 4 SRON, Laboratory for Space Research, Utrecht, Netherlands 4 SRON Laboratory for Space Research, Utrecht, Netherlands 4 SISSA - International School for Advanced Studies, via Beirut 2-4, I-34013 Trieste, Italy 4 SFA, Inc., Landover, MD, US 4 SETI Institute, Moffett Field, CA 4 SETI Inst., Moffett Field, CA 4 Rutherford Appleton Laboratory, Chilton, Didcot, UK 4 Rutherford Appleton Lab., Oxford, UK 4 Russian Academy of Sciences, Inst. for Problems in Mechanics, Moscow, Russia 4 Royal Observatory, Blackford Hill, Edinburgh, UK 4 Royal Greenwich Observatory, Apartado de Correos 321, Santa Cruz de La Palma, 38780 Tenerife, Canary Islands, Spain 4 Rothney Astrophysical Observatory, Calgary, Alberta 4 Research Centre of Crete, Heraklion, Greece 4 Real Inst. y Observatorio de la Armada, San Fernando, Spain 4 Purdue Univ., West Lafayette, IN, US 4 Purdue Univ., West Lafayette, IN 4 Potchefstroom University for CHE, Potchefstroom, South Africa 4 Pontificia Univ. Catolica de Chile, Santiago, Chile 4 Polish Academy of Sciences, Space Research Centre, Warsaw, Poland 4 Pic-du-Midi et Toulouse, Observatoires, Toulouse 4 Pic-du-Midi et Toulouse, Observatoires, Bagneres-de-Bigorre, France 4 Physics Department, University of York, Heslington, York YO1 5DD, UK 4 Phillips Lab., Aberdeen, MD, US 4 Owens Valley Radio Observatory, Caltech, Pasadena, CA, US 4 Osservatorio Astronomico di Torino, I-10025, Pino Torinese, Italy 4 Osservatorio Astronomico di Padova, vicolo dell'Osservatorio 5, I-35122 Padova, Italy 4 Osservatorio Astronomico di Brera, Via Brera 28, 20121 Milano, Italy 4 Osservatorio Astronomico di Brera, Via Bianchi 46, I-22055 Merate (CO), Italy 4 Osservatorio Astronomico di Bologna, via Zamboni 33, Bologna 40126, Italy 4 Osservatorio Astronomico di Bologna, Via Zamboni 33, I-40126 Bologna, Italy 4 Osservatorio 'Tito Lucrezio Caro', Bologna, Italy 4 Osaka University of Education, Osaka, Japan 4 Odessa State University, Odessa, Ukraine 4 Observatorio de Cordoba, Cordoba, Argentina 4 Observatorio Astronomico Nacional, Bogota, Colombia 4 Observatories of the Carnegie Institution, Pasadena, CA, US 4 Observatoire du Calern, Saint-Vallier-de-Thiey, France 4 Oak Ridge National Laboratory, Oak Ridge, Tenn. 4 Nuffield Radio Astronomy Observatory, Jodrell Bank, Ches., England 4 Nuffield Radio Astronomy Laboratories, Jodrell Bank, Macclesfield, Cheshire SK11 9DL 4 Notre Dame Univ., Notre Dame, IN, US 4 Northern Arizona Univ., Flagstaff, AZ, US 4 North Carolina State University, Raleigh, NC, US 4 North Carolina State University, Raleigh, NC 4 Nordlysobservatoriet, Tromso, Norway 4 Nordita, Copenhagen, Denmark 4 Newfoundland, Memorial University, St. John's, Canada 4 National Research Council of Canada, Ottawa, Canada 4 National Centre for Radio Astrophysics, Poona, India 4 National Central Univ., Chungli, Taiwan 4 National Center for Atmospheric Research 4 National Bureau of Standards, Washington, DC 4 National Bureau of Standards, Time and Frequency Div., Boulder, CO 4 National Bureau of Standards, Boulder, CO 4 NRAO/AOC, Socorro, NM, US 4 NOAA, Space Environmental Laboratory, Boulder, CO 4 NOAA, Space Environment Laboratory, Boulder 4 NIST, Quantum Physics Div., Boulder, CO 4 NBS, Quantum Physics Div., Boulder, CO 4 NASA, Johnson Space Center 4 NASA, Goddard Space Flight Center, Solar Maximum Mission Experiment Operations Facility, Greenbelt, MD 4 NASA, Goddard Space Flight Center, Cosmic Radiations Branch, Greenbelt, Md. 4 N. 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Belin, 31400 Toulouse, France 3 Observ. of the Carnegie Inst. of Washington, Pasadena, CA, US 3 Oak Ridge National Laboratory, Oak Ridge, TN 3 Nuffield Radio Astronomy Observatories, Jodrell Bank, England 3 Nuffield Radio Astronomy Labs., Manchester Univ., Manchester, UK 3 Nuffield Radio Astronomy Laboratories, Jodrell Bank, Macclesfield, Cheshire SK11 9DL, UK 3 Nuffield Radio Astronomy Laboratories, Jodrell Bank, Lower Washington, Macclesfield, Cheshire SK11 9DL, UK 3 Nuffield Radio Astronomy Laboratories, Jodrell Bank, Chesire, UK 3 Northern Colorado, University, Greeley, CO 3 North Carolina, University, Chapel Hill, N.C. 3 Niels Bohr Institute, Tollose, Denmark 3 New South Wales, University, Kensington 3 New South Wales, University, Campbell, Australia 3 New South Wales Univ., Canberra, Australia 3 New Mexico Institute of Mining and Technology, Socorro, NM, US 3 New Jersey Institute of Technology, Newark, NJ, US 3 New Alipore College, Calcutta, India 3 Netherlands Foundation for Research in Astronomy, Dwingeloo, The Netherlan 3 Netherlands Foundation for Radio Astronomy, Dwingeloo 3 National Research Council, Ottawa, Canada 3 National Research Council of Canada, Ottawa 3 National Central Univ., Chung-Li, Taiwan 3 National Center for Supercomputing Applications, Urbana, IL 3 National Bureau of Standards, Optical Physics Div., Washington, D.C. 3 National Astronomy and Ionosphere Center, Arecibo, Puerto Rico 3 National Air and Space Museum, Washington, DC, US 3 Napfizikai Obszervatorium, Debrecen, Hungary 3 Nanjing Univ., Nanjing, China 3 NSF, Div. of Astronomical Sciences, Washington 3 NRC of Canada, Victoria, BC, Canada 3 NORDITA, Blegdamsvej 17, DK-2100 Copenhagen, Denmark 3 NOAA, Space Environment Lab., Boulder 3 NOAA Space Environment Laboratory, Boulder, CO, US 3 NIST, Time and Frequency Div., Boulder, CO 3 NASA/Fermi National Accelerator Laboratory, Batavia, IL 3 NASA/Fermi National Accelerator Laboratory, Batavia 3 NASA. 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Copernicus Astronomical Center, Warsaw, Poland 3 Munich Univ., Scheinerstrasse, Munich, Germany 3 Multiple Mirror Telescope Observatory, Tucson, AZ, US 3 Multiple Mirror Telescope Observatory 3 Mullard Space Science Laboratory, University College London, Holmbury St Mary, Dorking RH5 6NT, Surrey, UK 3 Mullard Space Science Laboratory, Holmbury St. Mary, Dorking, Surrey RH5 6NT 3 Mullard Radio Astronomy Observatory, Madingley Road, Cambridge CB3 0HE, UK 3 Muenchen, Universitaetssternwarte, Munich, West Germany 3 Muenchen, Univ.-Sternwarte, Munich, Germany 3 Muenchen, Technische Universitaet, Munich, West Germany 3 Muenchen, Technische Universitaet, Munich, Federal Republic of Germany 3 Mount Suhora Observatory, Krakow Pedagogical University, ul. 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Nacionale de Astrofisica, Rio de Janeiro, Brazil 3 La Plata, Observatorio Astronomico, Argentina 3 L'Aquila, Universita, L'Aquila, Italy 3 Kutztown State College, Kutztown, Pa. 3 Krakow, Uniwersytet, Poland 3 Korea Astronomy Observatory, Taejon, Republic of Korea 3 Korea Astronomy Observatory, Taejon, Korea 3 Koninklijke Sterrenwacht van Belgie, Brussels, Belgium 3 King Abdulaziz University, Jeddah, Saudi Arabia 3 Kiepenheuer-Institut fuer Sonnephysik, Freiburg, Germany 3 Kiepenheuer-Institut fuer Sonnenphysik, Freiburg-im-Breisgau, West Germany 3 Kernforschungszentrum Karlsruhe GmbH, West Germany 3 Keldysh Institute of Applied Mathematics, Moscow, Russia 3 Keele University, Keele, Staffordshire, UK 3 Keele University, Department of Physics, Keele, Staffordshire ST55BG 3 Kashima Space Research Center, Kashima, Ibaraki, Japan 3 Kapteyn Astronomical Institute, Postbus 800, 9700 AV, Groningen, The Netherlands 3 Kapteyn Astronomical Inst., Groningen, Netherlands 3 Kanazawa Institute of Technology, Nonoichi, Japan 3 Joint Institute for VLBI in Europe, Dwingeloo, Netherlands 3 Joint Astronomy Centre, 660 N. 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Argentino de Radioastronomia, Villa Elisa, Argentina 3 Inst. Argentino de Radioastronomia, Argentina 3 Insititute of Technology, Cambridge, MA, 02139 3 Indonesian National Institute of Aeronautics and Space, Djakarta, Indonesia 3 Indiana University, Bloomington, Indiana, US 3 Indian Institute of Astrophysics, Koramangala, Bangalore 560034, India 3 IUE Observatory, Villafranca, Spain 3 IPAC, California Institute of Technology, 770 South Wilson Avenue, Mail Code 100-22, Pasadena, CA 91125, USA 3 INFN - Sezione di Perugia, c/o Dipartimento di Fisica dell'Universita, via A. 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Tuebingen, Tuebingen, Germany 3 Astronomical Observatory, Purple Mountain, People's Republic of China 3 Astronomical Instituut 'Anton Pannekoek', Amsterdam, Netherlands 3 Astronomical Institute, St Petersburg State University, Bibliotechnaya pl. 2, 198904 St Petersburg Peterhof, Russia 3 Astronomical Institute ``Anton Pannekoek'', University of Amsterdam, Kruislaan 403, NL--1098 SJ Amsterdam, The Netherlands 3 Astronomical Institute ``Anton Pannekoek'', University of Amsterdam, Kruislaan 403, 1098 SJ Amsterdam, The Netherlands 3 Astronomical Institute `Anton Pannekoek', University of Amsterdam, Center for High Energy Astrophysics, Kruislaan 403, 1098 SJ Amsterdam, The Netherlands 3 Astronomical Inst., Academy of Sciences, Ondrejov, Czech Republic 3 Astrofisico di Arcetri, Firenze, Italy 3 Armagh Observatory, Northern Ireland, UK 3 Arcetri, Osservatorio, Florence, Italy 3 Arcetri Astrophysical Observatory, Firenze, Italy 3 Anglo-Australian Observatory, PO Box 296, Epping NSW 2121, Australia 3 Anglo-Australian Observatory, Coonabarabran, New South Wales 2357, Australia 3 Andalucia, Inst. de Astrofisica, Granada 3 Akademiia Nauk SSSR, Institut Zemnogo Magnetizma, Ionosfery i Rasprostraneniia Radiovoln, Irkutsk, USSR 3 Aix-Marseille III, Universite, Marseille, France 3 Aix-Marseille I, Universite 3 Affiliated to the Space Sciences Division of ESA, Space Telescope Science Institute, 3700 San Martin Drive, Baltimore, MD 21218, USA 3 Aerospace Corp., Space Sciences Laboratory, El Segundo, Calif. 3 Aerospace Corp., Los Angeles 3 Aerospace Corp., Ivan A. 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Oxford University, Keble Road, Oxford OX1 3RH 2 Astrophysics, Nuclear Physics Laboratory, Oxford, UK 2 Astrophysics, Keble Road, Oxford OX1 3RH 2 Astrophysics Group, Liverpool John Moores University, Byrom Street, Liverpool L3 3AF 2 Astrophysics Group, Blackett Laboratory, Imperial College of Science, Technology and Medicine, Prince Consort Road, London SW7 2BZ, UK 2 Astrophysics Division, Rutherford Appleton Laboratory, Chilton, Didcot, Oxon OX11 0QX 2 Astrophysics Department, University of Sydney, NSW 2006, Australia 2 Astrophysical Observatory, Catania, Italy 2 Astrophysical Observatory, Asiago, Italy 2 Astronomy and Astrophysics Center, The University of Chicago, Chicago, IL 60637, USA 2 Astronomy Unit, School of Mathematical Sciences,Queen Mary and Westfield College, Mile End Road, London E1 4NS 2 Astronomy Unit, School of Mathematical Sciences, Queen Mary and Westfield College, University of London, Mile End Road, London, UK 2 Astronomy Unit, School of Mathematical Sciences, 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Aoba-ku, Sendai, 980-77, Japan 2 Astronomical Institute, St Petersburg University, Bibliotechnaya pl. 2, 198904 St Petersburg Peterhof, Russia 2 Astronomical Institute, Faculty of Science, Tohoku University, Sendai Miyagi 980-77, Japan 2 Astronomical Institute ``Anton Pannekoek'', University of Amsterdam, Kruislaan 403, 1098 SJ Amsterdam, The Netherlands and Dpto. 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Anton Pannekoek, Amsterdam Univ., Amsterdam, Netherland 2 Astro Space Center, Lebedev Physical Institute, Profsoyuznaya 84/32, 117810 Moscow, Russia 2 Astro Space Center of P. N. 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Ioffe Institute of Physics and Technology, St. Petersburg, Russia 2 A.F. Ioffe Institute for Physics and Technology, St. Petersburg, Russia 2 A. F. Ioffe Institute for Physics and Technology, 194021 St. Petersburg, Russia 2 6127 Wilder Laboratory, Department of Physics and Astronomy, Dartmouth College, Hanover NH 03755, USA 2 61 Rosebery Street, Bedford, 6052 Western Australia 2 1150 University Avenue, Space Astronomy Laboratory, University of Wisconsin, Madison, WI 53706, USA 1 {CNR - Istituto di Fisica Cosmica e Tecnologie Relative, Via Bassini 15, 20133 Milano, Italy and Dip. Fisica, Universita di Milano, Via Celoria 16, 20133 Milano, Italy 1 te 142, 4 place Jussieu, 75005 Paris, France 1 internet: zacs@acad.latnet.lv 1 california, University, Berkeley, Calif. 1 and Visiting astronomer, Cerro Tololo Inter-American observatory, operated under contract No. AST 78-27879 1 and Universitatssternwarte Munchen, Scheinerstr. 1, D-81679 Munchen, Germany 1 and URA 173 (associee au CNRS et a l'Universite Paris 7) et DAEC, Observatoire de Paris, F-92195 Meudon, France 1 and Max--Planck--Institut fur Extraterrestrische Physik (MPE), Giessenbachstrasse, Postfach 1603, D-85740 Garching, Germany), AB- 1 and Istituto Nazionale di Ottica, Largo E. Fermi 6, I--50125 Firenze, Italy 1 and Dpto. Fisica Teorica C--XI, Facultad de Ciencias, Universidad Autonoma de Madrid, Cantoblanco, E--28049 Madrid, Spain 1 acutesica de Canarias, E-38200, La Laguna, Tenerife, Canary Islands, Spain 1 Zuerich, Eidgenoessische Technische Hochschule, Zurich, Federal Republic of Germany 1 Zhongshan University, Guangzhou, People's Republic of China 1 Zentralinstitut fuer Astrophysik, Tremsdorf, Federal Republic of Germany 1 Zentralinstitut fuer Astrophysik, Potsdam, Federal Republic of Germany 1 Zagreb, Sveuciliste, Hvar, Yugoslavia 1 Yunnan Observatory, Chinese Academy of Sciences, Kunming, China 1 Yunnan Observatory, Academia Sinica, P.O.Box 110, Kunming 650011, China and Center for Astrophysics, CCAST (World Laboratory), Beijing, China 1 Yunnan Observatory, Academia Sinica, P.O.Box 110, Kunming 650011, China 1 Yunnan Normal Univ., Kunming, China 1 Yunnan National College, Kunming, China 1 Yunnam Observatory, Kunming, People's Republic of China 1 Yukawa Institute for Theoretical Physics, Kyoto University, Kyoto 606-01, Japan 1 Yukawa Institute for Theoretical Physics 1 Yuge National College for Maritime Technology, Ehime, Japan 1 Yuge National Coll. of Maritime Technology, Ehime, Japan 1 York University, Department of Physics and Astronomy, 4700 Keele Street, North York, Ontario, M3J 1P3, Canada 1 York Mills Collegiate Institute, North York, Canada 1 Yerevan Physics Institute, Alikhanian Brothers 2, 375036 Yerevan, Armenia 1 Yale University, New Haven, Connecticut, US 1 Yale Astronomy Department, New Haven, CT 06520-8101, USA 1 Xinjiang Institute of Technology, Urumqi, People's Republic of China 1 X-ray Astronomy Group, University of Leicester, University Road, Leicester LE1 7RH, UK 1 X-ray Astronomy Group, Department of Physics & Astronomy, University of Leicester, University Road, Leicester LE1 7RH, UK 1 Wyzsza Szkola Pegagogiczna, Rzeszow, Poland 1 Wyzsza Szkola Pedagogiczna, Rzeszow 1 Wyoming, University, University Station, WY 1 Wuppertal, Universitaet-Gesamthochschule, West Germany 1 Wroclaw University, Wroclaw, Poland 1 WorldView Imaging Corp., Livermore, CA, US 1 Wolfsburg, Planetarium, West Germany 1 Wolf Research and Development Corp., Riverdale, Md. 1 Witwatersrand Univ., Wits, South Africa 1 Witwatersrand Univ., South Africa 1 Wittenberg Univ., Springfield, OH, US 1 Wise Observatory & School of Physics and Astronomy, Raymond and Beverly Sackler of Exact Sciences, Tel Aviv University, Tel Aviv, 69978, Israel 1 Wise Observatory & School of Physics and Astronomy, Raymond and Beverly Sackler Faculty of Exact Sciences, Tel Aviv University, Tel Aviv, 69978, Israel 1 Wisconsin-Parkside, University, Kenosha, Wis. 1 Wisconsin-Madison, University, Madison, Wis. 1 Williams College, Williamstown, Mass. 1 Wilhelm-Foerster-Sternwarte, Berlin, West Germany 1 Wilhelm-Foerster-Sternwarte, Berlin, Federal Republic of Germany 1 Westfalische Wilhelms-Universitat, Munster, Germany 1 Western Washington State University, Bellingham, WA 1 Western Ontario, University, London, CA 1 Western Ontario Univ., London, Ontario, Canada 1 Western Montana College, Dillon 1 Western Carolina University, Cullowhee, NC, US 1 Western Australia, University, Perth, Australia 1 Western Australia, University, Crawley, Australia 1 Westerbork, Radiosterrewacht Zwiggelte, Netherlands 1 Westerbork, Radiosterrenwacht, Hooghalen, Netherlands 1 Westerbork, Radiosterrenwacht Zwiggelte, Netherlands 1 West Virginia University, Morgantown, WV 1 West Virginia University, Morgantown, W. Va. 1 West Georgia College, Carrollton, GA 1 Wesleyan Univeristy, Middletown, Conn. 1 Weedin Place, Seattle, WA, US 1 Waseda Univ., Okubo, Tokyo, Japan 1 Warszawa, Uniwersytet, Observatorium Astronomiczne, Warsaw, Poland 1 Warszawa, Uniwersytet, Astronomiczne Obserwatorium, Warsaw, Poland 1 Warszawa, Universytet, Warsaw, Poland 1 Warszawa, Obserwatorium Astronomiczne, Warsaw, Poland 1 Warsaw University Observatory, Al.Ujazdowskie 4, 00-478 Warsaw, Poland 1 Warsaw University Observatory, Al. Ujazdowskie ~4, 00-478 ~Warsaw, Poland, e-mail: jka@sirius.astrouw.edu.pl; Guest Observer, Cerro Tololo Inter-American Observatory, NOAO, operated by the Associations of Universities for Research in Astronomy Inc., under contract with the National Science Foundation. 1 Warsaw University Observatory, Al. Ujazdowskie ~4, 00-478 Warsaw, Poland, e-mail: jka@sirius.astrouw.edu.pl, Visiting Astronomer, Kitt Peak National Observatory. KPNO is operated by AURA, Inc., under contract with the National Science Foundation. 1 Warsaw University Observatory, Al. Ujazdowskie 4, Pl-00478 Warszawa, Poland 1 Warsaw University Observatory, Al. Ujazdowskie 4, 00-478, Warsaw, Poland 1 Warsaw Univ. Astronomical Observatory, Warsaw, Poland 1 Warner and Swasey Observatory, East Cleveland 1 Warner and Swasey Observatory, Cleveland OH 1 Warner & Swasey Observatory, Cleveland, OH 1 Wallongong, University, Wallongong, New South Wales, Australia 1 WIP Astronomie/Universitat Potsdam, Sternwarte Babelsberg, An der Sternwarte 16, D--14482 Potsdam, Germany 1 W.M. Keck Science Center, Claremont, CA, US 1 Vysoka Skola Banska, Ostrava, Czechoslovakia 1 Visiting Fellow, Astronomy Centre, Univ. Sussex, Falmer, Brighton, BN1 9QH, UK and Dept. Physics \& Astronomy, Univ. St. Andrews, North Haugh, Fife, KY16 9SS, Scotland 1 Visiting Astronomer, Kitt Peak National Observatory, National Optical Astronomy Observatories, operated by AURA Inc., under contract with the National Science Foundation. 1 Visiting Astronomer, Canada-France-Hawaii Telescope operated by the National Research Council of Canada, the Centre National de la Recherche Scientifique de France and the University of Hawaii 1 Virginia, Polytechnic Institute and State University, Blacksburg, VA 1 Virginia Polytechnic and State University, Blacksburg, VA 1 Virginia Polytechnic Institute and State Univesity, Blacksburg, VA 1 Virginia Polytechnic Institute and State University, Charlottesville, VA 1 Virginia Polytechnic Institute and State University 1 Virginia Polytechic Institute and State University, Blacksburg, VA 1 Virginia Military Institute, Lexington 1 Vinius Astronomical Observatory, Vilnius, Lithuania 1 Vilnius Observatory, Vilnius, Lithuania 1 Villeneuve-d'Ascq, Nord, France 1 Villafranca Satellite Tracking Station, Madrid, Spain 1 Victoria University, Wellington, New Zealand 1 Victoria University of Wellington, Wellington, New Zealand 1 Victoria Univ., Wellington, New Zealand 1 Victoria Univ. of Wellington, Wellington, New Zealand 1 Vicolo dell' Osservatorio, Padova, Italy 1 Veszpremi Vegyipari Egyetem, Veszprem 1 Vermilion River Observatory, Danville, Ill. 1 Vereniging voor Sterrenkunde, Brussels, Belgium 1 Verein der Sternfreunde, Fachgruppe Meteore, Veitsbronn, Germany 1 Vatican Observatory Research Group 1 Vassar College, Observatory, Poughkeepsie, NY 1 Vassar College Observatory, Poughkeepsie 1 Vassar Coll., Poughkeepsie, NY, US 1 Vassar Coll. 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European Southern Observatory, Garching, West Germany 1 CNRS, Laboratoire de Physique Atomique et Moleculaire et d'Instrumentation en Astrophysique 1 CNRS, Laboratoire de Photophysique Moleculaire, Orsay, France 1 CNRS, Laboratoire de Photophysique Moleculaire, Orsay, Essonne, France 1 CNRS, Laboratoire de Photophysique Moleculaire, Orsay 1 CNRS, Laboratoire de Meteorologie Dynamique, Palaiseau, Essonne, France 1 CNRS, Laboratoire de Glaciologie et de Geophysique de l'Environnement, Saint-Martin-d'Heres, France 1 CNRS, Laboratoire d'Astrophysique, Meudon, Hauts-de-Seine 1 CNRS, Laboratoire d'Astrophysique Extragalactique et de Cosmologie 1 CNRS, Laboratoire d'Astrophysique 1 CNRS, Laboratoire d'Annecy-le-Vieux de Physique des Particules, France 1 CNRS, Laboratoire d'Annecy-le-Vieux de Physique des Particules 1 CNRS, Laboratoire d'Annecy-le-Vieux de Physique des Particles, France 1 CNRS, Laboratoire d'Aerothermique, Meudon, Hauts-de-Seine, France 1 CNRS, Laboratoire d'Aerothermique, 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Physique de l'Environnement Terrestre et Planetaire, Orleans, France 1 CNRS and CNET, Centre de Recherche en Physique de l'Environnement Terrestre et Planetaire, Orleans, France 1 CNRS URA, St Vallier de Thiey, France 1 CNRS (URA 173), Meudon, France 1 CNR, Unita di Ricerca di Padova-Asiago, Padua 1 CNR, Unita di Ricerca di Asiago-Padova, Italy 1 CNR, Laboratorio per il Plasma nello Spazio, Frascati 1 CNR, Laboratorio di Tecnologie e Studio delle Radiazioni Extraterrestri, Florence, Italy 1 CNR, Laboratorio di Tecnologie e Studio delle Radiazioni Extraterrestri 1 CNR, Laboratorio di Tecnologie e Studio delle Radiazioni Estraterrestri, Florence, Italy 1 CNR, Laboratorio di Tecnologie e Studio delle Radiazioni Estraterrestri 1 CNR, Laboratorio di Tecnologie e Studio Radiazioni Extraterrestri, Bologna, Italy 1 CNR, Laboratorio di Ricerca e Tecnologia per lo Studio del Plasma nello Spazio, Frascati, Italy 1 CNR, Laboratorio di Radioastronomia 1 CNR, Laboratorio di Fisica Cosmica e Technologie Relative, Palermo, Italy 1 CNR, Laboratorio di Fisica Cosmica e Technologia Relativa, Milan, Italy 1 CNR, Laboratorio di Cosmogeofisica, Turin 1 CNR, Laboratorio de Fisica Cosmica e Tecnologie Relative, Milan, Italy 1 CNR, Laboratorio de Fisica Cosmica e Tecnologie Relative 1 CNR, Laboratorio Tecnologie e Studio Radiazoni Extraterrestri, Bologna, Italy 1 CNR, Laboratorio Tecnologie e Studio Radiazioni Extraterrestri, Bologna, Italy 1 CNR, Laboratorio Fisica Cosmica, Milan, Italy 1 CNR, Laboratorio Fisica Cosmica e Tecnologie Relative, Milan, Italy 1 CNR, Laboratorie di Fisica Cosmica 1 CNR, Laboratoria di Cosmogeofisica, Turin, Italy 1 CNR, Istituto per le Applicazioni del Calcolo, Rome, Italy 1 CNR, Istituto per la Fisica dell'Atmosfera, Rome, Italy 1 CNR, Istituto di Tecnologie e Studio delle Radiazioni Extraterrestri, Bologna 1 CNR, Istituto di Tecnologie e Studio Radiazioni Extraterrestri, Bologna, Italy 1 CNR, Istituto di Technologie e Studio delle Radiazzioni Estraterrestri, Bologna, Italy 1 CNR, Istituto di Technologie e Studio delle Radiazoni Extraterrestri, Bologna, Italy 1 CNR, Istituto di Technologie e Studio delle Radiazioni Extraterrestri, Bologna, Italy 1 CNR, Istituto di Technologie e Studio delle Radiazione Extraterrestri, Bologna, Italy 1 CNR, Istituto di Studio e Tecnologie sulle Radiazzioni Estraterrestri, Bologna 1 CNR, Istituto di Studio e Tecnologie sulle Radiazioni Extraterrestri 1 CNR, Istituto di Studio e Tecnologie sulle Radiazioni Estraterrestri, Italy 1 CNR, Istituto di Studio e Tecnologia sulle Radiazioni Extraterrestri, Italy 1 CNR, Istituto di Spettroscopia Molecolare, Bologna, Italy 1 CNR, Istituto di Ricerca sulle Onde Ellettromagnetiche, Florence, Italy 1 CNR, Istituto di Fisica della Atmosfera, Rome, Italy 1 CNR, Istituto di Fisica Spazio Interplanetario, Frascati, Italy 1 CNR, Istituto di Fisica Spazio Interplanetario, Frascati 1 CNR, Istituto di Fisica Cosmica ed Informatica, Palermo, Italy 1 CNR, Istituto di Fisica Cosmica ed Applicazioni all'Informatica, Palermo, Italy 1 CNR, Istituto di Fisica Cosmica e Applicazioni dell'Informatica, Palermo 1 CNR, Istituto di Fisica Cosmica e Applicazioni dell' Informatica, Palermo, Italy 1 CNR, Istituto di Fisica Cosmica con Applicazioni all'Informatica, Palermo 1 CNR, Istituto di Elettronica dello Stato Solido, Rome, Italy 1 CNR, Istituto di Elettronica Quantistica, Florence, Italy 1 CNR, Istituto di Astrofisica Spaziale, Frascati, Roma II, Universita, Rome, Italy 1 CNR, Istituto di Astrofisica Spaziale and Istituto per il Plasma nello Spazio, Frascati, Italy 1 CNR, Istituto di Astrofisica Spaziale 1 CNR, Istituto Plasma Spazio, Frascati, Italy 1 CNR, Istituto Plasma Spazio 1 CNR, Istituto Nazionale di Fisica Nucleare, Pisa, Italy 1 CNR, Istituto Nazionale di Fisica Nucleare, Padua 1 CNR, Ist. per le Applicazioni del Calcolo, Rome, Italy 1 CNR, Ist. per le Applicazioni Interdisciplinari della Fisica, Palermo, Italy 1 CNR, Ist. di Tecnologie e Studio delle Radiazioni Extraterrestri, Italy 1 CNR, Ist. di Tecnologie e Studio delle Radiazioni Extraterrestri, Bologna 1 CNR, Ist. di Studio e Tecnologie sulle Radiazioni Extraterrestri, Bologna 1 CNR, Ist. di Studio e Tecnologie sulle Radiazioni Extraterrestri 1 CNR, Ist. di Studio e Tecnologie delle Radiazioni Extraterrestri, Bologna, Italy 1 CNR, Ist. di Studio e Tecnologie delle Radiazioni Extraterrestri, Bologna 1 CNR, Ist. di Fisica dell'Atmosfera, Rome, Italy 1 CNR, Ist. di Fisica Cosmica ed Applicazioni dell'Informatica, Palermo, Italy 1 CNR, Ist. di Fisica Cosmica ed Applicazioni all'Informatica, Palermo, Italy 1 CNR, Ist. di Fisica Cosmica con Applicazioni all'Informatica, Italy 1 CNR, Gruppo Nazionale per l'Astronomia, Rome, Italy 1 CNR, Gruppo Nazionale per l'Astronomia, Naples, Italy 1 CNR, Gruppo Nazionale per l'Astronomia, Italy 1 CNR, Gruppo Nazionale di Struttura della Materia, Florence, Italy 1 CNR, Gruppo Nazionale di Astronomia, Naples, Italy 1 CNR, Gruppi Italiani di Fisica Cosmica, Palermo, Italy 1 CNR, Centro per l'Astronomica Infrarossa e lo Studio del Mezzo Interstellare, Florence, Italy 1 CNR, Centro per l'Astronomia Infrarossa e lo Studio del Mezzo Interstellare, Arcetri, Italy 1 CNR, Centro per l'Astronomia Infrarossa e lo Studio del Mezzo Interstelare, Florence, Italy 1 CNR, Centro per l'Astronomia Infrarossa e Ro Studio del Mezza Interstellare, Florence, Italy 1 CNR, Centro Nazionale Universitario di Calcolo Elettronico, Pisa, Italy 1 CNR - Istituto di Fisica Cosmica ed Applicazioni dell'Informatica, Via Mariano Stabile 172, 90139 Palermo, Ital