(cba:news) More on AH Men = Tafelberg
jop at astro.columbia.edu
Mon Nov 23 06:05:40 EST 2020
Hi (mostly southern) CBAers,
Working through the 2020 data on AH Men, I note one feature that really
helps in the period searches. The star has somewhere between 3 and 5
identifiable periodic signals, but there's hardly any of the
night-to-night nonperiodic variability ("noise" to us) which hampers the
study of virtually all CVs. The mean nightly brightness hardly changes
at all. This means that you can breezily append nights together for a
many-night period search, without some intermediate mathematical
adjustment (e.g. subtract the mean) which can possibly hide a true
signal or reveal a bogus signal. Nice!
And, in particular, it means that you can merge data sets from the three
major land masses in Earth's nether regions: South Africa, South
America, Australia. And we have ace observers in all three!
But since we do differential photometry, it's important that we not
change comparison stars during a year's campaign.
Except for the last, these are not recommended practices in general.
Cataclysmics will eat you alive if you assume that magnitude 15.73 on a
Monday means the same thing as 15.73 on a Tuesday. Night-to-night
erratic variability is usually much stronger than the small periodic
(and therefore interpretable) signals we like to study.
David Buckley reminded me that we once called this star "Tafelberg", and
i used that alluring name in talks I gave about it, and in my 1995
paper. I'm not sure quite why, but i certainly like the practice of
stellar nicknames. I know Algol, the Demon Star... and 61 Cygni, the
Flying Star. Can you write and tell us of others you know?
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