(cba:news) FY Per, WZ Sge, IGR1955-00, finis; new stars for Oct-Nov

Joe Patterson jop at astro.columbia.edu
Thu Oct 26 18:25:46 EDT 2017

Hi CBAers,

We've reached season's end with several stars:

1) WZ Sge and IGR1955-00, because the runs are getting short now.
2) FY Per, because there's a LOT of data, and I want to study it 
carefully before resuming coverage.  It varies on the orbital timescale, 
and also apparently with some longer period that I haven't yet figured 
out.  What I haven't found yet is the 1.5 hour period that originally 
motivated our program.  To be continued after full analysis of the 
several hundred hours of data!
3) V339 Del, because its variability is really minuscule.  Very 
surprising for this recent nova... and interesting, but further coverage 
would probably just improve the no-periodic-signal (and hardly any 
variability at all) result.

here's a menu of juicy Oct-Nov-Dec targets.

OY CAR, Z CHA, U GEM.  All famous eclipsing dwarf novae.  We've had a 
lot of recent success with tracking eclipsing stars... and, more 
arguably, with interpreting their orbital-period variations.  So let's 
try that with these guys.  U Gem should be an easy target; OY Car and Z 
Cha are harder (esp. since the critical data occur near mid-eclipse).

BT Mon (a 1939 nova).  Same comments.  Faint in mid-eclipse, BUT the 
eclipse is long and symmetrical, so mid-eclipse can be timed even with 
lousy data near the bottom.  The orbital period is almost exactly 8 
hours, so for some observers, there may be no night-time eclipses for 
many weeks.

V959 Mon, RR Pic, T Pyx.  Classical novae which we are studying for 
their orbital-period signals (and variations).  T Pyx is slightly 
off-season, but plenty suitable since the period is sufficiently stable 
to make full use of relatively short runs (2-3 hours).

BY Cam and "Paloma" (RXJ 0524+42).  Apparently "asynchronous polars"... 
and we're devoted to following their (slowly) wandering periods.

DQ Her stars (intermediate polars).  V418 Gem, V1033 Cas, V902 Mon, BG 
CMi, and V598 Peg.  Except for the last (of which I'm not sure), these 
are all pretty straightforward targets - not requiring long runs 
(thought profiting from length) and not requiring every-night dense 
observation.  The objective is to string together a bunch of timings 
(say 10-20) each observing season, to derive a long-term ephemeris.

Finally, ES Cet.  We're about to fire off our paper on this 10-minute 
binary... but each observing season form now on will have significant 
impact, because sensitivity to period change increases with the SQUARE 
of the baseline.  So it remains a fine target. It's the first CV to 
demonstrate the controlling influence of gravitational radiation in 
evolution - and we didn't even have to smash the stars together to do it!

joe p

p.s. I've not said much about priority in this long list.  I will after 
seeing some of the data.  Also, you can get a pretty good idea from 
looking at your own data - except for the faintest stars, which usually 
only yield their secrets after a lot of teamwork.
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