Acknowledgement

Over the years, I received lots of kind feedback and improvement hints for which I am very grateful. I am also much olbliged for the many interesting discussions on the celestial topics I had with many of you:

  Tony (Russia)
  Marco
  Yannis (Greece)
  Arnaud (Equador)
  Francis (United Kingdom)
  Joachim (Germany)
  Larry (United Kingdom)
  Magnus
  Russell (USA)
  Samuel
  Fabrice
  Ralph (Germany)
  Charles
  Luc (Belgium)
  Ignatios
  Andy (United Kingdom)
  Anaya (Japan)
  Alan
  Colin (Canada)
  Darren (Canada)
  Jorge (Argentina)
  Fernando (Chile)
  Sean
  Noel
  David (USA)
  Ian (New Zealand)
  Ottar (Norway)
  Kjell (Norway)
  John
  Elias (Germany)
  Lille (Italy)
  Fred
  Wayne (USA)