单项选择题
A.Prime vertical circle B.Principal vertical circle C.Parallels of altitude D.Horizon
In order for a star to be used for a sight at lower tra...
单项选择题In order for a star to be used for a sight at lower transit，the star must（）.
A.be circumpolar B.have a declination equal to or greater than your latitude C.have a GHA of 180° D.have the SHA equal to or less than the LHA
In low latitudes，a first quarter Moon will always rise ...
单项选择题In low latitudes，a first quarter Moon will always rise at about（）.
A.sunrise B.1200 LMT C.sunset D.2400 LMT
In general，the most effective period for observing star...
单项选择题In general，the most effective period for observing stars and planets occurs during the darker limit of（）.
A.sunset B.civil twilight C.nautical twilight D.astronomical twilight
