(cba:news) Stars for April/May

Joe Patterson jop at astro.columbia.edu
Mon Apr 28 19:46:06 EDT 2003

Dear CBAers,

Well, Rod reports that V551 Sgr faded fast.  Probably a normal outburst...
there's some chance it'll trigger a super, but usually not.  Off the menu.

The two really good southern targets now are EX Hya and the newly
discovered DQ Her star 1RXSJ154814.5-452845 (periods probably 11 min and
either 9.4 or 6.7 hours).  We should be able to define these periods very
precisely and get long-term ephemerides for such a friendly star (14.5)
located at -45.  The only catch is a 13th mag star just east of the
variable.  If you search the CV catalogue for "Lup", you'll see the
situation.  Doesn't look too difficult, maybe 9 arcsec or so... you should
be able to manage, but just need to be aware in case of very bad seeing or
jumpy drives.  Looks like a winner!

In the NORTH...

If you can reach RX0625+73, it's definitely worth covering for a few
weeks.  Then we pick up again after it comes out of the Sun (ha!). Could
get a year of coverage with no systematic substantial breaks... now
there's a way to beat aliases!

In the morning sky, it's worth starting a new campaign now on MV Lyr.
This star waffles around between 12.5 and 18... bounces around so much and
so fast that it's been awfully tricky to analyze time series.  We found it
around 12.7 ten years ago, and obtained a brief campaign showing marginal
evidence for superhumps.  Borisov (92) did the same - also marginal
evidence, but at least near the same period.  Who knows?  Anyway, we can
do a MUCH better campaign now.  It's a little early for these coords
(1907+44), but I'm afraid the star might not stay near 12th mag very long.
So let's do it.

Earlier in the night, we need to keep going on HZ Her for at least 20 more
days, to cover the full 35-day precession cycle.  Great data coming in on
that, from Dave Messier, Jerry Foote, Tom Krajci, Tonny Vanmunster, Bob
Fried.  And before that, try GZ Cnc again.  It just jumped back into
eruption, and might finally show the waves that have eluded us in
quiescence.  About 13.5 I think.

Time to retire CR Boo.  And give a rest to V533 Her; it'll still be there
in 1-2 months, whereas MV Lyr could be a fleeting proposition.

Finally, IM Nor, the eclipsing recurrent nova.  This is a difficult star
but is I think the most important of the southern targets.  With small
apertures (like most CBA), it needs quite good conditions - little moon
and good seeing.  Berto got one good run - let's see if we can get another
half-dozen and patch together a good eclipse timing (by the way, it's a
*shallow* eclipse - "dip" might be a better word).


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