Datamining the Variability Sample Catalogue from SOGS

[Martin Nicholson (NMR)]

The Variability Sample Catalogue from SOGS (Fresneau+, 2009) has two
parts each listed in Vizier:

Objects detected along meridian l=330°
and
Objects detected along the galactic equator


There is some overlap between objects in these two surveys but when
you compare the quoted V and B band magnitudes for such objects the
results are somewhat strange.

In the V band (based on 100 stars) the average difference is 0.0009
(range +0.23 to -0.16) BUT in the B band the average difference is
0.3289 (range +0.79 to -0.2)

I would have expected the average difference in the magnitudes to have
been close to 0 and I cannot think off the top of my head of an
explanation for the B band figures.

Any thoughts?