(cba:news) HP Lib (only) (Joe Patterson) [2019-07-05T12:18:09Z]

Hi CBAers,

The HP Lib campaign is almost finished.  The main result has emerged: 
0.08 mag superhump and 0.003 mag (peak-to-trough!) orbital signal, with 
the latter certified as orbital because of its high phase stability 
(over at least 4 years).  And amazingly low erratic variability on long 
(night-to-night) and short ("flickering") timescales.  A true twin of AM 
CVn in all these respects (and others).

This was the most difficult measurement I have ever made.  The 
sought-after signal is down by 30x in amplitude (and thus 900x in power) 
from the nearby superhump signal, which inevitably is surrounded by aliases.
Often a long campaign ends on a note of "we'll do better next year". 
This time, it ended - or shortly will end - on a note of "Wow!"

We need 2 more weeks to lengthen the baseline now, to connect to next 
February's time series, which will put the yearly cycle count beyond 
doubt (for that 2020 observation, we need only measure the *phase*, not 
an independent period).  Right now there's an obvious best candidate for 
the precise period, but we'd like to upgrade from "best candidate" to 
"proven".

So... two more weeks - and at lest two northerners (Tonny and Shawn D.) 
have successfully coped with the evening twilight and southern dec, and 
contributed important time series.  So think about it.  And for 
southerners: get thee to a telescope (although, granted, you already 
have; Berto, Gordon, and Josch get the Medal of Honor on this one).

joe

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