(cba:news) AM CVn - take it to the bank! (Jonathan Kemp) [2025-05-11T19:54:36Z]

---------- Forwarded message ----------
Date: Sun, 11 May 2025 15:45:44
From: Joe Patterson <jop@xxxxxxxxxxxxxxxxxx>
To: cba-news@xxxxxxxxxxx
Subject: AM CVn - take it to the bank!

Hi CBAers,

Your diligence on AM CVn has royally paid off.  I now see that the star's three
periods are clearly delineated - the two superhumps at 1051 and 1011 s - both
specified to high precision... plus the true Porb at 1028 s.  All consistent
with what we thought in 2019, along with the dPorb/dt which is the best treat of
all, since it probably specifies the basic nature of the binary (wd + helium
star).

So: no need to continue on AM CVn/  Instead let's turn to CR Boo, a close
relative and, at a dec of +8 degrees, available to both hemispheres.  It has
some low states (17th) but is otherwise a close relative... and the desired
observing technique is the same.  I especially hope that our non-USA observers
can be active on Mr. Boo.

Then there are the Hercules boys - V1674, DQ, and V533.mainly.  At 18.7 ot so,
V1674 wants long runs on dark nights .  DQ is much more forgiving... but
integrations must be short, and watch out for the eclipse (not a threat, but the
star DISAPPEARS very briefly every 4.6 hours).   Finally, V533 Her is quite a
long shot - hasn't been seen to pulse since the 1980s - but practically no one
is looking!  63 s, so keep integrations short (and durations long).

More on other  targets later today...

joe

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