Apr 28, 2012

Shuttle prototype Enterprise

Shuttle prototype Enterprise atop B747 at the Aerosalon in Le Bourget in June 1983

See gallery for more scanned slides

Apr 7, 2012

Besselsche Elemente

Everything you may want to know about Besselian Elements but were afraid to ask is answered in this prize-winning Wikipedia article in German (abridged English version or Google translation).

"Besselsche Elemente" und "Dagobert Duck" - das sind die Themen der beiden Wikipedia-Artikel, die [2010] als besonders hervorragend ausgezeichnet worden sind (Wikimedia Blog, Heise, PediaPress Books for the Zedler Medal)

Background by the author J├╝rgen Erbs
Die Besselschen Elemente: Ein Mauerbl├╝mchen im Rampenlicht

Main sources used are
_ Explanatory Supplement to the Astronomical Almanac, ed. Seidelmann 2006,
contents identical to the 1992 edition and
_ Spherical astronomy, Robin M. Green 1985

On Apr. 02, 2012 John Tilley noted on the Yahoo eclipse mailing list SEML Message #14663:
"The 1992 Explanatory Supplement is NOT recommended, there are several mistakes in the formulae and no worked examples"

Here is a computational example for the total solar eclipse on 1961 Feb 15
from the "Explanatory Supplement to the Astronomical. Ephemeris and the American Ephemeris and Nautical Almanac" 1961, 4th impression 1977

 scans pp. 211-224

In Astronomie mit dem Personal Computer 
   Astronomy on the Personal Computer
by Oliver Montenbruck, Thomas Pfleger,
Springer 4. Aufl., 2004, XIII, 302 S. 46 Abb. Mit CD-ROM.
a method is presented of computing eclipses and local circumstances dispensing with Besselian Elements.