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R scuti

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#1 Otto Piechowski

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Posted 29 June 2013 - 12:08 AM

I was scanning the Milky Way from Cygnus to Sagittarius with binoculars and decided to look at the Wild Duck cluster. When I found it, I wasn't sure I had found it, because the four star asterism containing R Scuti next to the cluster looked so very strange. What made it appear strange was that it only seemed to be a three star asterism; caused by the dimmest I have ever seen R Scuti, right around magnitude 8.

Otto

#2 Ben Therrell

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Posted 29 June 2013 - 02:05 AM

AAVSO chart on Wikipedia shows it as faint as 7.5. Why don't you keep track of it for a while?

#3 Hubert

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Posted 29 June 2013 - 05:39 AM

The latest observations of R Sct are around magnitude 8.5
It has reached magnitude 9 and somewhat fainter. The faintest observations in decades.

#4 BrooksObs

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Posted 29 June 2013 - 07:47 AM

Indeed, the little asterism that includes R Sct currently does look a bit peculiar with the variable as faint as it is. However, minima as deep as the present one the variable is exhibiting aren't really all that uncommon. The most recent instance came back in 2005 and a series of similarly deep dips were recorded between 1993 and 1995.

R SCT-type variables are not known for replicating their lightcurves cycle-to-cycle like MIRA-type variables do. Most minima of R Sct are fairly modest and one can never really anticipate just when the next very deep minimum is likely to occur. In fact, R Sct occasionally even displays periods of near inactivity, where little in the way on any clear cyclic pattern has been evident at all!

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#5 Hubert

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Posted 30 June 2013 - 05:51 AM

If you plot a lightcurve for the last 80 year you can see that this minima is the faintest in the last 80 years. So a minima like this does not occur very often.

I agree the minima are often but never seems to reach that faint as this one.

#6 BrooksObs

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Posted 30 June 2013 - 08:20 AM

Hubert - Speaking as someone who has closely followed R Scuti for some 50 years as a member of AAVSO, I can vouch that the star's current minimum is actually no deeper than those occurring most recently in 1996, 1987, and previously. What we happen to have in the current instance are a handful of estimates of rather poor quality scattered well below the mean of the rest of the data. While a simple, long-term, plotting (say 80 years) of the lightcurve does suggest this to be an unusually deep minimum, if one calls up a plot of just the past 100 days the erroneously faint data becomes strikingly obvious.

Unfortunately, being a very bright and easily located variable, R Scuti is heavily observed by newbies and rather poor observers, often leading to distortion in its overall lightcurve.

BrooksObs

#7 Hubert

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Posted 30 June 2013 - 11:31 AM

Hello Brooks,

I can't argue that R Sct is indeed a star followed by many newbie's. It's also on the starters program from the Belgian workgroup variable stars.

I go along with your conclusion.






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