(cba:news) new moon, new stars

Joe Patterson jop at astro.columbia.edu
Thu Feb 10 10:08:55 EST 2005

Dear CBAers,

Time for updates re target stars.

Mostly from Greg Bolt's initiative (and tenacity), we've accumulated a
nice bundle of data on PU CMa.  I include the "pre-whitened" (mean and
trend roughly removed from each night) time series of the first nine
nights.  This is the series you'll want to inspect for period-finding
issues.  Have fun with it!  However, I notice that the power spectrum is a
little odd - as if the star suddenly changed properties within the time
series, or there is a timing error within it.  I didn't study it closely
enough to pin this down... but since many of you are interested in this, I
thought I'd send it out.

Despite this oddity, which may be real, there's decent coverage of two
previous outbursts - so I'm inclined to call an end to the PU CMa
campaign.  Maybe not right away, though - a few more nights would be

Bob Rea has been observing T Pyx, and his data shows the 110 min signal
we've been following for lo these many years.  We have a pretty good
timing on it.  Time to quit on T Pyx until April/May.  (We've been trying
for early/late season coverage.)

The remaining bright southern target is AH Men, dutifully covered mainly
by Berto, Tom Richards, Bill Allen.  This one definitely wants a few more
weeks of coverage.  It's got a big negative superhump, worth considerable
close study.

Two new southern targets deserve to be tossed into the mix.  The first is
WX Pyx.  This is very faint, at 17.7, but it has a large-amplitude
photometric signal - likely to be due to magnetically channeled accretion.
We'd like to track the period sufficiently closely to establish a
long-term ephemeris... and I think that good 2005 coverage will accomplish
that.  Since the target is faint, you'll want to reserve good nights for
this one.

The other is RX1039-05 ("Com").  Even fainter, but it has a *huge*
infrared signal, which you probably can track with any sort of
red/infrared filter.  It's also OK for white light, though the amplitude
is less.  You'll need long integrations for this 18th mag star - but will
likely profit from learning more about your system performance at 18th

I realize these are ambitious!  But hey, there's AH Men - a piece o' cake
at 12.7 or so.

In the NORTH, I propose to replace BH Lyn; the first run by Dave Messier
showed no obvious superhump, and I'm inclined not to pursue it further.
I'd like to elevate the other two existing targets: FS Aur and HS 0728+67.
Jerry Foote has been doing yeoman service on FS Aur, and his data show
that 2004-5 has been unusual, with the photometry showing the orbital as
well as the "mysterious" 3.5 hour period.  I dunno when we'll figure this
out... but we need to keep looking.

HS0728+67 has been on our books for a few weeks... but so far, no takers.

The other northern target we need to cover is RX0625+73 ("Cam").  We did a
good job last year, and another good season will get us to critical mass
for publication.  Plenty bright, an easy target! Very nice totational and
orbital signals.

Now for something different.  My assumption for a long time has been that
CBAers are best equipped for time-series study, since that requires just
one setup, plus an automated data reduction.  We've never tried the CCD
versions of the visual outburst seekers... with the exception of a few
individuals (Berto, obviously).  I'd like to design such a program -
say with 50 important stars essentially too faint (or in a few cases
too new) to have a known outburst behavior.  But how many CBAers would
be interested in this (likely much more laborious) program?


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