Sat, 05/06/2017 - 18:44
I have been following this star in its ascending portion of the light curve since January. It seems to me that S UMI is diplaying an hump. Although the star has not reached the maximum brightness yet, I can see a sort of hump at all passbands (BVI). Currently I am the only observer to observe this star with CCD and filters.
Gianluca (RGN)
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Well, looking at the lightcurve over the past 10 years, there are a few other times it has shown a "hump" or hiccup or "standstill" on it ascending branch. Definitely a similar one in mid-2015, one in Jan 2011. But other years do not show such behavior in the same way, though some years like 2014 and 2016 show a brief "standstill" just before maximum.
From cycle to cycle the behavior it's different. Sometimes the light curve shows humps but in other cycles it's very similar to a double maxima.
S UMi is already on the LPV Hump list. So, this behavior was already known or suspected. I think you can say that this is a confirmation.