[Aavso-photometry] 94 star near GW Lib

[arne]

After my reply to Barbara, several people mentioned that
this star (GSC/TYC 06766-01577, HD 136234)
is also found in the Washington Double Star Catalog,
with components about V=9.4 and V=11.8, with separation of
2arcsec at position angle 160 degrees.  It appears that
Tycho2 was able to split these two stars; at least, the
magnitude listed in the main Tycho catalog appears to be
just the primary star, with the secondary star magnitude
given separately in the Tycho Double Star Catalog.

Most observers (including Sonoita) will see this pair as a
blended object, and report the sum of the magnitudes.
Slawson et al., 1992, ApJS 82, 117, did a large photometric
project of stars in the Sco-Cen association, including
HD136234.  They quote:

   V = 9.194  +/- 0.007
B-V = 0.308  +/- 0.009
U-B = 0.236  +/- 0.013

or equivalently,
U = 9.738
B = 9.502
V = 9.194

ASAS gives V=9.21 +/- 0.03, in agreement with the value above.

My Sonoita B-band images show the object as blended, with a slight
elongation to the south.  The untransformed B magnitude is 9.51,
in agreement with Slawson.

Therefore, I would suggest that people use the Slawson magnitudes listed
above for this comparison star.  We'll get Rc/Ic as soon as Arizona
has clear weather.

Sorry for the confusion on this one.  Luckily for CCD observers,
you can reprocess your data and resubmit, once the field is properly
calibrated.  Visual observers should start using 92 instead of 94
for this star and report the change in the comments.
Arne