(cba:news) ASASSN-18ey... and AM CVn

Joe Patterson jop at astro.columbia.edu
Tue Mar 12 09:02:32 EDT 2019

Hi CBAers,

Joe U's discovery of the rebrightening of our old friend from last year 
is posted on ATel 12567 (they post these things in <15 minutes, so be 
careful when you send!).  Let's brave those cold March mornings to find 
what's going on with Maxi.  With that long period of 17 hours. we can't 
cover an orbit (except by splicing data from several longitudes).  But 
with a V filter, you can start well above our usual limit of 2.0 
airmasses (even to 3.0), because the extinction is fairly low and 

And let's go after AM CVn with similar intensity.  March is a great 
season for this star, and although the raw light curve doesn't look like 
much, it is flashing at least two superhumps (positive at 525.6 s - the 
first overtone - plus the 1028 s orbital signal.  With enough time 
baseline, we get to see those periods *change* - minutely but with great 
consequences for the star's structure and evolution.  LONG time series 
are needed, but stick with a clear or minus-blue filter (so adhere to 
the <2.0 airmass convention).

joe p

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