noun
planisphere; star chart wheel
A rotating star chart used to see which constellations are visible at a given date and time.
星座早見を使って今夜の星空を調べた。
I used a planisphere to check tonight's starry sky.
星座盤 is a more general term for a star chart or constellation board, while 星座早見 specifically refers to a rotating planisphere.
Compound of 星座 (constellation) and 早見 (quick reference chart). The term 早見 is used for various quick-reference tables or charts.