Photometric asymmetry between clockwise and counterclockwise spiral
  galaxies in SDSS
  While galaxies with clockwise and counterclockwise handedness are visually
different, they are expected to be symmetric in all of their other
characteristics. Previous experiments using both manual analysis and machine
vision have shown that the handedness of Sloan Digital Sky Survey (SDSS)
galaxies can be predicted with accuracy significantly higher than mere chance
using its photometric data alone, showing that SDSS photometry pipeline is
sensitive to the handedness of the galaxy. However, some of these previous
experiments were based on manually classified galaxies, and the results may
therefore be subjected to bias originated from the human perception. This paper
describes an experiment based on a set of 162,514 celestial objects classified
as clockwise and counterclockwise spiral galaxies in a fully automatic process,
showing that the source of the asymmetry is more than the human perception
bias. The results are compared to two smaller datasets, and confirm the
observation that the handedness of SDSS galaxies can be predicted by their
photometric information, and show that the position angle of counterclockwise
galaxies computed by SDSS photometry pipeline is consistently higher than the
position angle computed for galaxies with clockwise patterns. The experiment
also shows statistically significant differences in the measured magnitude,
according which galaxies with clockwise patterns are brighter than galaxies
with counterclockwise patterns. The magnitude of that difference changes across
RA ranges, and exhibits a strong correlation with the cosine of the right
ascension.
