[vsnet-chat 3031] RE: [vsnet-obs 28038] ETA CARINAE - Two years of observations

[Sebasti若n Otero <varsao@fullzero.com.ar>]

Hi,Bish and VSNET friends:
                                                 It's great that we can
share data and comments about this star.
                                                 I hadn't paid attention to
the one-year period and it's true that it can be caused by the star's
altitude: it seems brighter when low, which is exactly what would happen to
a red star in a more illuminated sky. When I say "red" I mean, of course,
star and envelope together, which appear orange to me.
                                                 Given the circunstance that
we are looking not at a punctual source but a combination of nebulosity and
star (noticeable even in binoculars), the visual estimates are not the same
as with other stars. I know that different observes use different ways of
observing these stars. Some use averted vision, some look straight to the
stars and others apply the defocusing method. Personally I don't like the
latter because the stars must be of the same color for a reasonable
comparison. The more you defocuse the image, the fainter it becomes and then
the blue stars appear brighter as we approach the limitting magnitude of our
instrument (See Hallett,P., Human nocturnal spectral sensitivity and
photoelectric V, JAAVSO,vol.26,1998).
So each observer has its own way of dealing with Eta. That's why it gets
tough to merge everyone's observations. But if we take all the observations
for the same individual, I notice that most of them are watching the star
fade. It's a challenge to prove if our eyes are being cheated or if we are
witnessing a real fade. We must keep observing to find out. The range is
small but I'd bet that the star has declined a liitle bit.
                                                   If something happens
around September 2000, according to Bish's predictions, that would be a good
chance but the worst period of the year for Eta Carinae observing, since
it's low in the South. (You know Murphy's Law...) That would be a great
opportunity for southernmost observers to do their homework. And of course,
for HST to do it as well.

Best regards,
Sebasti睹 Otero.

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