(cba:news) The month of HP Lib

Joe Patterson jop at astro.columbia.edu
Thu Jun 11 17:26:14 EDT 2020

Hi CBAers,

I'm getting plenty of data now on DQ Her, and have some very accurate 
pulse timings - enough to establish a very accurate phase during June 
2020.  It's time to put the star aside until october  (late-season 
timings make it possible to ascertain a unique cycle count between one 
season and the next).

The urgent need now is HP Lib.  We are getting good coverage from Berto 
in South Africa, and from several European observers.  But you 
norteamericanos - other than Tut Campbell - seem to be averse to that 
southerly declination.  How scary can -14 degrees be?  At mag 13.8 and 
with a 0.05 mag rapid oscillation, it's a pretty easy target for every 
observer.  Long runs are nice of course, but anything >2.5 hours would 
be useful.

As with AM CVn, HP Lib's main signal is a superhump - in itself, not all 
that interesting.  But with a really strong campaign, we can subtract 
the superhump and find the weak orbital signal in the residuals.  In 
addition, we can search for a negative superhump, like in AM CVn.  It is 
such a dead ringer for AM CVn... I bet that negative superhump is in 
there, happy to emerge once our detection limits get just a little bit 

Later in the night, V1494 Aql and V1974 Cyg are definitely juicy targets 
for you northerners.  More in a few days.

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