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We study the number density distribution of a sample of K and M dwarf stars,matched North and South of the Galactic plane within a distance of 2 kpc fromthe sun, using observations from the Ninth Data Release of the Sloan DigitalSky Survey. We determine distances using the photometric parallax method, andin this context systematic effects exist which could potentially impact thedetermination of the number density profile with height from the Galactic plane--- and ultimately affect a number density North-South asymmetry. They include:(i) the calibration of the various photometric parallax relations, (ii) theability to separate dwarfs from giants in our sample, (iii) the role of stellarpopulation differences such as age and metallicity, (iv) the ability todetermine the offset of the sun from the Galactic plane, and (v) the correctionfor reddening from dust in the Galactic plane, though our stars are at highGalactic latitudes. We find the various analyzed systematic effects to have anegligible impact on our observed asymmetry, and using a new and larger sampleof stars we confirm and refine the earlier discovery of Widrow et al. of asignificant Galactic North-South asymmetry in the stellar number densitydistribution.

The Stellar Number Density Distribution in the Local Solar Neighborhood is North-South Asymmetric