<正>Simultaneous multi-wavelength observations have revealed complex variability in AGNs. To explain the variability we considered a theoretical model consistin
New CCD photometric observations for asteroid(1028)Lydina,carried out with the 1-m and 2.4-m telescopes at Yunnan Observatory from 2011 December 19 to 2012 Febr
The fuel consumption associated with some interplanetary transfer trajectories using chemical propulsion is not affordable. A solar sail is a method of propulsi