(cba:news) targets for mid-April

Joe Patterson jop at astro.columbia.edu
Fri Apr 20 06:53:18 EDT 2012

Dear CBAers,

I hope/expect to see you a bunch of you (I think ~10-12) at the Big 
Bear/AAVSO meeting.  As usual, we'll have a few meals together and 
perhaps meet once to discuss common issues.  Enrique and I have been 
scrambling to get our papers submitted (basically on ER UMa and BK 
Lyn)... and I haven't managed to dig up all the authors' addresses.
(Since it's a 20-year campaign, it's not that easy.)  In a few days I'll 
send the submitted version to authors.  Partly because the time-series 
data is so rich, I've decided to postpone the detailed analysis and 
highlight the glamor points (only short-period novalike, only novalike 
to morph into a dwarf nova, oldest recovered nova).

The long-term campaigns are all going well.  The Sun's relentless 
eastward march has reduced ER UMa and BK Lyn to evening-only status, but 
they're still good targets for another few weeks.  The other really 
long-term campaign targets, CR Boo and V803 Cen, deserve a continued 
high priority.  In a few days I'll have 'em analyzed enough to give a 

Then there's AM CVn. It's *definitely* time to get some long runs on 
that star.  MANY long runs.  This is definitely the month, when it 
transits near midnight and the nights are still decently long.  Since 
it's always near 14.2, it's bright enough for everyone and at all tmes 
(even the Moon stays away from Can Ven).  I had thought we had a secure 
orbital-period decrease through 1992-2010, but made the mistake of 
wanting to confirm with 2011 data.  Great was my chagrin when I saw the 
2011 timings of orbital minimum occurring 0.10 cycles late.  Was this 
just a fluke, to be quickly overcome by the 2012 timings?  Or was I just 
too quick on the draw before that?  This coming season should 
determine... and will constrain the angular-momentum loss rate of the 

Finally, and potentially a real gem, there's the bright Seyfert nucleus 
of MCG-6-30-15.  Encarni Romero Colmenero is about to start a long 
spectroscopic monitoring campaign ("reverberation mapping") from SALT, 
and needs daily V magnitudes for a couple months, starting now.  She'll 
write to this address and specify details... but it looks like a really 
good fit for us.  At a dec of -34, I assume this is strictly a southern 
object, though some of you borealites might be feeling adventurous. 
Anyway, read up on this fascinating galaxy and its central object, make 
a chart, find a comp star, and measure a few magnitudes - through V, or 
Sloan g, or unfiltered.  Try to figure out how you would observe - which 
filter, how to cope with galaxy background, etc.  Measure *vastly* more 
more than one magnitude per night; that will improve knowledge of 
errors, and help define the true, unknown timescales of variability. 
I'm sure Encarni will send information on these matters.


More information about the cba-public mailing list