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I have a dataset of a binary star system's magnitudes taken over the past decade, obtained from AAVSO. These magnitudes are reported in B,V,R,I, and so on. Some magnitudes have their V magnitudes given, which are the Johnson V magnitudes. Other magnitudes, however, are taken in the 'Vis' band. Aren't these two bands the same? Doesn't the V in Johnson's classification stand for the visual band, centered at 551nm? AAVSO's website differentiates between Vis and V without providing an explanation. How do I resolve these magnitudes? Is there a way to convert a V magnitude to a Vis magnitude?

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For AASVO, Vis refers to estimates made visually by an observers eyeball. The best observers get to 0.1 magnitude accuracy, but mostly 0.2. V is for the V band in the Cousins/Johnson system.

If you have a lightcurve with both measurements, there will be just an offset between the 2 measures , Unless the variables' color changes at lot. I have not heard of anybody that bothers doing a full transformation.

Note Red stars are trickier to estimate visually. The longer you look the brighter they look (the Purkinje effect).

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