(cba:news) April-May stars (Joe Patterson) [2020-04-26T13:14:21Z]

Dear CBAers,

Some shiny new targets for the southern fall.  Happens every year.

"Nova Sco 1437".  We have excellent data from 2018, but strangely missed 
coverage last year.  It's a deep eclipser, an IP, and possibly the 
remnant of an ancient nova.  Seems not to have a variable-star name yet. 
In southern Scorpius, it's for the australites only... but is worth 
pounding very hard on these long southern nights.

V407 Lupi (Nova Lupi 2016).  Another superb choice, with orbital and IP 
modulations.  Recently discovered (obviously).

IM Nor.  Yet another old (recurrent) nova.  Usually near 18th mag, so 
this might be a Gordon-only target.

V617 Sgr and WX Cen.  Two supersoft (according to me; there are 
dissenters) binaries with large dP/dt terms in their eclipse 
ephemerides. Easy targets; at -35 degrees, V617 might be available to 
some northerners.

V1223 Sgr.  At V=13 minutes and delta = -31, this one is available to 
most northerners.  We - along with everyone else - have neglected this 
famous IP, and it's time to establish a solid ephemeris.

- - - -
THE AM CVN STAR CAMPAIGNS.

I recommend continuing on AM CVn for another ~3 weeks, to give those 
superhumps a chance to change their periods (slightly but importantly!). 
 No need for very long runs, though.

I recommend backing off on V803 Cen... and somewhat on CR Boo (latter is 
debatable).  These stars are in their oscillating states ("dwarf-nova"), 
and those are very, very difficult to analyze.  Should either star get 
very faint (V>17), then they become high priority targets.

HP Lib.  Definitely.  Very good target!  Long runs highly recommended, 
although all runs will be helpful.

SDSS J141118.31+481257.6.  Back in the sky, perfectly placed.
- - - -

MAXIE (J1820+070).  Keep watching.  Short time series, unless it erupts.

V1494 Aquilae.  We have to keep tracking this very bright and eclipsing 
1999 nova.

DQ Her .  Time to resume our watch.  Timing of the eclipse is of 
interest, but try to get a timing on the 71 sec oscillation.  This is 
not difficult to do in a lengthy time series, but requires a cycle time 
(time between mid-integrations) of 25 seconds or less.

OV Boo. This is a definite reach, at V~18 and eclipsing.  But just a few 
eclipses this year will get the binary ephemeris nailed down, and the 
paper finished at last.

joe

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