36th DPS Meeting, 8-12 November 2004
Session 18 Outer Planets
Poster I, Tuesday, November 9, 2004, 4:00-7:00pm, Exhibition Hall 1A

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[18.01] Long Term Changes in the Reflectivity of Uranus

R. W. Schmude, Jr. (Gordon College)

Photoelectric magnitude measurements of Uranus made during the last 77 years through the Johnson V passband (peak wavlength = 540 nm, bandpass = 85 nm) are presented. Hardie and Giclas (1955) applied color corrections to magnitude measurements of Uranus made before 1955; additional magnitude data for this study were taken from Appleby and Irvine (1971), from Schmude (2002) and from unpublished data. Between 1991 and 2003, Uranus dimmed by about 0.06 magnitudes. Larger brightness changes than in the 1990s were measured during the first 60 years of the 20th century. Since the polar flattening of Uranus is only about 0.02, it is concluded that the brightness changes measured on Uranus during the last 77 years are primarily due to changes in the reflectivity of Uranus' atmosphere.

Appleby, J. F. and Irvine, W. M. (1971) Astron. J. 76, 617; Hardie, R. H. and Giclas, H. L. (1955) Astrophys. J. 122, 460; Schmude, R. W. Jr. (2002) The Strolling Astonomer 44, 22.

The author(s) of this abstract have provided an email address for comments about the abstract: Schmude@gdn.edu

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Bulletin of the American Astronomical Society, 36 #4
© 2004. The American Astronomical Soceity.