Comparison star missing magnitude label

American Association of Variable Star Observers (AAVSO)
Wed, 11/15/2017 - 18:33

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!






American Association of Variable Star Observers (AAVSO)
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.



American Association of Variable Star Observers (AAVSO)
Re "large scale" charts

You mentioned "large scale" in your reply above.  As a new member, I was wondering about those large scale charts in the 10 Star tutorial.  The Star Plotter only goes up to 1200 arc min.  I assume those very wide area charts are done by AAVSO using a different software program other than VSP.  I really would like to be able to do wider area charts as finder charts/educational purposes but I suppose we don't have that ability through VSP.  Any suggestions? 

I have used "" sky atlas to some limited success.  They only have "bright-intermediate-faint" filters so the inability to set magnitude limits is a serious liability.  The dots/stars don't seem to agree sometimes with AAVSO's VSP but again likely due to a "magnitude mystery limit" in In-the-Sky's tool.

I also found some of the finder charts using the AAVSO Atlas cluttered and confusing.  The Bayer Greek letters only are hard to read in smaller scales, dim light, bad eyes, etc.  It just looks cluttered.  I realize they don't use Flamsteed desig because so much is crammed into so little space so they keep the designation to a minimum.  I prefer names with some magnitudes, helps locate key areas where your search can have a starting point for patterns, asterisms around your target.  

Thx, Bob 

American Association of Variable Star Observers (AAVSO)

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!


American Association of Variable Star Observers (AAVSO)
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.