I have been observing the R CrB-type variable, Z UMi for a few months now. I have a question which concerns the 12.5 comparison star on the AAVSO preliminary chart. Is this star variable? I have noticed what appear to be small changes in magnitude with this star. (about .3 of a mag) These alleged changes are occurring independent of seeing conditions, Moon phase, etc... Have any other observers noticed or commented on this? I know the chart is preliminary, which is subject to change but, I have had some problems with accurately estimating the variable when one star in the comparison sequence is suspect. On a different note but still dealing with Z UMi: Were there any recently published articles concerning the possibly reclassification of Z UMi? I have spoken with another observer who believes there is but does not recall the specific journal. Any assistance/guidance you can give me would be greatly appreciated. Thank you.
Lance Shaw (SQN)
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