stars for early July

From: Joe Patterson <*jop_at_astro.columbia.edu*> Date: Sat, 03 Jul 2010 20:46:36 -0400 · jop_at_astro.columbia.edu

                                                             July 3, 2010.
Dear CBAers,

    Time to clear the decks for new stars.  V699 Oph and TY Vul have faded
back from outburst, and are no longer worth tracking.  V795 Her is showing
some weak periodic humps, but the amplitude and phase coherence are pretty
low - too low for us to improve on our result from the 1990s.  Let's
give up on it.  V841 Oph has been worth a look, but no periodic signals
are popping up; let's abandon that one too.

    V1084 Her = RX1643+34 is a tough case.  A lot of good data on this
star... but the star's behavior is *extremely* similar to what we described
in our 2002 paper, and we're not actually improving on it.  This is hard
in the northern summer, because the European nights are so short.  So
I'm inclined to say: give up on V1084 Her too.

    OT2138+26 is a great new star for the CV zoo, and it gets 4 minutes
better every day.  HOWEVER, the eruption is almost all over, and it's
still about 1.5-2 months before we can crank up a good campaign at
quiescence.  So I'm inclined to say: leave the star until late August,
when we'll mount another campaign (presumably in quiescence).

    GW Lib really needs additional long time series now!  In about 10 days,
the waxing Moon will invade Libra again, and end the observing season for
good.  But until then, I hope that southern observers - and even southern
USA ones, who can bridge our usual South Africa -> NZ gap.

   We have a GW Lib paper nearly ready to send off, with great data from
2007 (the year of outburst) and 2008 (which showed the return of pulsations,
and a new 4-hour periodicity).  We just need to bundle the 2010 data in
there too; so far it's just a little thin, but another solid week of
coverage - with long time series - will bring it up to par.

   All these disappearing stars leaves room for new ones.  There are three
stars for which we want to mount campaigns starting *approximately* now.
These are V1315 Aql, HS1813+61 (Dra), and V603 Aql.  All of them have
rewarded our efforts in the past... but another solid season of observation
will make a much stronger paper.  I recommend waiting another ~3 weeks for
V603 Aql - it will make a great two-hemisphere target which will survive
any amount of moonlight.  The other two are ready for action now.  Pick
one and go as long as possible!  

   Finally, there's V4743 Sgr.  We only need a *few* decent runs on this -
just enough to verify that our yearly cycle count for Porb and Prot is
correct (which then establishes it for the full 2003-2010 series).  I'm
90% sure based on last year's work - but a little work now will get that
up to 100% (or, less likely, 0%).  Bob Rea has gotten ~2 runs; I think we
need ~5 more, as accuracy is hurt somewhat by the star's faintness and
crowded neighborhood.

   That's a good prescription for July, assuming so no startling new
dwarf novae pop off.

                       joe
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