[AZ-Observing] Re: [Fwd: Re: Re: Rapid motion binary stars]

>>  REU 1   12:33.5 +0901, 12.6/12.6, 15.9 year period, max 1.2", min 0.2"

     The first thing I do when I ponder an object like this is to
find out where it actually is:

12 33 17.41 +09 01 15.7  (J2000)

That position is for the year 2000, and it is moving 1".7 per year
to the west-northwest.
     The magnitudes:  it happens to be a Landolt standard, a star that
people use to calibrate photometry.  Landolt gives mean V mag of 12.(5
(rounding off), so if the components are exactly equal, they are
mag 13.2 and 13.2, actually visually a couple tenths fainter,
because the pair are so red (B-V = 1.85 --- as red as Betelguese).
     The faint magnitudes and very close separation (mostly under 0".5)
indicates the pair will be visible only in maybe 24-inch and larger
scopes with great optics and perfect seeing.  I'd stick to naked-eye
stars for such objects.


>>  LDS 838 01:38.8 -1758, 12.45/12.95, 26.5 year period, max 2.3", min 0.3"

     Another very well-known nearby binary, in this case moving twice
as fast as the first pair, about 3".5 per year proper motion.  The position
as of 6 years ago was:

1 39 01.52 -17 57 01.7  (J2000)

    Similar comments about the visibility as above apply to this pair.


     A better, more general approach might be to grab the entire
orbit file from USNO, linked from here:

http://ad.usno.navy.mil/wds/orb6.html


I would delete everything that has components fainter than mag 7 or so.
Then delete everything that has orbit grade of 4 or 5 (all the lousy
orbits).  Then I'd delete everything that has a semimajor axis 
less than an arcsecond.  Just as a guess, that'll leave at most 50 
pairs (whole-sky) that are bright enough to see when close and have
some fairly significant motion.  Might be only a dozen in the north.


\Brian
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