We present an investigation of the USNO-A2.0 Catalog positions. We have compared USNO-A2.0 positions with the Astrographic Catalogue-Tycho, with improved HST Guide Star Catalog positions in the ACT frame, and with International Celestial Reference Frame source positions and observational data from Valinhos CCD Meridian Circle, covering all the USNO-A2.0 magnitude range within 7 ≤ V ≤ 22. We report striking, peculiar features first found for the USNO-A2.0 catalog positions, which are different for its northern and southern parts.
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Assafin et al. (2001) studied this question.
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