I calculated the altitude of Negai*" using 'Newton solution of Keplerian equation'. I noticed that the altitude follows a drop line slowly.

http://www.ne.jp/asahi/hamradio/je9pel/00531ne2.jpg

For more details, http://www.ne.jp/asahi/hamradio/je9pel/newtnkep.htm

JE9PEL, Mineo Wakita