I'm impressed by your efforts. I mentioned this
type of thing briefly in a chat note a day or so ago. In 30 years' of measures
at Auckland Observatory we found the sky was littered with red variables of low
amplitude and rather irregular habits. But the GCVS required that you gave some
indication of the type of variability and a decent light curve before listing so
these were merely consigned to a list of stars unsuitable for visual
comparisons. There were other more important objects. But I notice that there
are a number of objects now listed in the GCVS where this criterion has not been
followed - or where the details show some imaginative interpretation of the
data.
How reliable is the Hipparcos photometry? I
compared it with one or two known low amplitude objects and was surprised by the
results. Sigma Octantis was one of these where the Hipparcos data showed a much
lower amplitude than ground-based results. Maybe it picked all the times when
the beat period amplitude was low? We're only talking 4-7% again.
Your mention of AG Carinae made me look at the
JAAVSO but I found that it was AG Ceti that Marinova and Percy analysed. But
they had some interesting ideas about what the Hipparcos data showed, fitting
several possible periods from 1.3 to 5.5 days to the measures. So I wonder about
the period of 2.91 days you mention. It's not in a good position at the moment
but I night try some BVRI photometry next season.
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