North polar sequence
Star sequence defining magnitudes and colors
From Wikipedia, the free encyclopedia
The North polar sequence is a group of 96 stars that was used to define stellar magnitudes and colors.[1] The cluster of stars lies within two degrees of the Northern Celestial pole.[1] That fact makes them visible to everyone in the northern hemisphere.[2]
Originally proposed by Edward Charles Pickering, the system was used between 1900 and 1950. Today it has been replaced by the UBV photometric system.
