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(cba:news) FY Per, WZ Sge, IGR1955-00, finis; new stars for Oct-Nov (Joe Patterson) [2017-10-26T22:26:35Z]


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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