(cba:news) VZ Scl campaign

Joe Patterson jop at astro.columbia.edu
Sun Oct 29 11:47:54 EDT 2017

Hi CBAers,

Thanks to Berto and Gordon, we are accumulating a great campaign on VZ 
Scl this year... and it seems to be rewarding our efforts with deep 
eclipses (as always) and superhumps (that's new).  However, there are no 
actual time overlaps between the two stations (Australia and South 
Africa).  In some years coverage from these stations can bridge the 
Indian Ocean gap, but it just hasn't happened this year; and of course 
we can never bridge the Atlantic plus Pacific gap!

So we need coverage from the Americas.  Josch might be able to help us, 
but another possibility is North American coverage.  It's a challenge at 
this declination, but some of our southern USA observers might be able 
to handle it.  Shawn or Tut, perhaps?

We can calibrate* to within ~0.06 mag even without this help, but 
simultaneity of coverage reduces that error to ~0.02 mag.  That would be 
good.  But don't mess with huge variability in airmass, because that's a 
systematic error we really can't tame at all.


*BTW "calibrate" means reduce to a COMMON INSTRUMENTAL MAGNITUDE. 
That's pretty much what we always seek.  The more ambitious goal of 
arriving at a STANDARD magnitude (Sloan, Johnson, etc.) is usually
beyond our scope... and is basically irrelevant to our goal (periodic 
signal searches). Just for the record, though, our instrumental 
magnitudes are usually ~0.2 mag fainter than a Johnson V.  That's 
assuming you report so-called "CV" magnitudes, which most of you do.
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