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RY Ursae Majoris

RY UMa is a semiregular variable of type SRa, meaning it has reasonably stable pulsations over part of its history, but with lower amplitude than their Mira-type cousins.  In this case, RY UMa has a well-defined pulsation period around 310 days, but it also has a supercycle of several thousand days during which the pulsations apparently cease.  It's not clear why this is the case.  RY is a bright variable for the northern hemisphere, well within range of most observers including binocular observers.

AAVSO 49 Bay State Rd. Cambridge, MA 02138 617-354-0484