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Comparison star missing magnitude label

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raymondhow's picture
Comparison star missing magnitude label

Hi guys, first post on the forum here.  Getting my feet wet with VSO, starting out with Delta Cep of course.  Have a question...

I generated chart X21538GHU with the VSP.  Nice chart, but it does not include a magnitude label for Zeta Cep.  Odd that it's missing, because the 10 Star Tutuorial labels it 34.  I was able to report my observation of Delta Cep anyway, and indicated 34 as my first comp star.

So why would the label for Zeta be missing?  In general, is there a way to force VSP to add a label for a particular star?

Clear skies!






Sebastian Otero
Sebastian Otero's picture
Zeta Cep, small amplitude variable

Hi Raymond,

At some point the star may have been removed from the comparison star sequence due to its variable nature. It has a 0.09 mag. range around V= 3.35. It is also rather red (B-V= 1.56).
It might not be a bad comparison star for visual use due to it being close and similar in brightness to delta Cep's maximum but it shows many disadventages.
Since charts for naked eye variables need a much larger scale than the one VSP allows, the 10 Star tutorial chart might be a good choice to use. The label may have been removed after the tutorial was published.
I don't think using it will cause a big issue but I would wait for other observer's comments.
Maybe keeping it with a note "Only for visual use" like we do with other low amplitude variables would do.



raymondhow's picture

Thanks Sebastian.  Looking at recent observations of Delta Cep, I see the 10 star tutorial chart is specified often.  So I'll run with that.

So in general, if a magnitude label is missing, sounds like there's probably a good reason for it.  Good to know.  Clear skies!


Unlabeled comps

If you think a particular star should be labeled (or if you are hoping for additional comps etc.), there is a link at to send your request to the AAVSO Sequence Team.  Sebastian is on that team, I believe, and they are very responsive to those messages. 

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