[vsnet-chat 7478] Re: [AAVSO-DIS] Antares (and delta Sco) faint

[Sebastián Otero]

Thom,

>    Thanks for your post.  It was of great interest!   I can not make
> very accurate visual estimates, but I have noticed that delta Sco
> is much fainter lately.  Also, Antares seemed a lot fainter to me,
> but I couldn't be sure because there are no good comp stars
> visible from here.  I'm glad to hear my casual observations are
> confirmed!


The three main comparison stars now are three multiple systems with a beta 
Cephei component!! That's all we have but due to the small amplitude of 
those variations and the intrinsic scatter due to the color differences, 
that's not a problem for visual use.
It is not an easy star though.
Those 3 stars with their mean values are:

Spica (alp Vir) V= 0.98 (also the recently discovered EA with 0.005 mag. 
eclipses ;)
Mimosa (bet Cru) V= 1.26
Shaula (lam Sco) V= 1.62

When Antares is at maximum, I use Acrux (alp Cru) as the comp star (V= 0.75)

Northern observers can replace it with Altair (alp Aql, V= 0.77) but at 
minimum there are few useful (or close) comp stars to the North.


Best wishes,
Sebastian.