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

CC BY-SA 4.0
2021-09-17T06:43:44.587Z
2021-09-17T06:43:44.587Z
TazAstroSpacial
<p>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?</p>

<photometry><magnitude>
Is there a difference between Vis and V when analyzing the magnitudes of stars?
requiemman
# Is there a difference between Vis and V when analyzing the magnitudes of stars?

(Asked by: username_0 on 2021-09-10)

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?

**Tags:** photometry, magnitude


---

## 1 answers

### Answer by username_1 on 2021-09-17. Score: 3 | Accepted answer

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).


---

