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Lightcurve data for Europa has been very hard to interpret, so much so for a long time its period of rotation was in dispute (5 and a half, or 11 hours?) despite many observations<sup>[[#Zappala83|[8]]]</sup>. It has now been determined that Europa is a prograde rotator, but the exact direction in which its pole points remains unclear. The most detailed analysis indicates that it points either towards about [[ecliptic coordinate system|ecliptic coordinates]] (β, λ) = (70°, 55°) or (40°, 255°) with a 10° uncertainty <sup>[[#Michalowski04|[2]]]</sup>. This gives an [[axial tilt]] of about 14° or 54°, respectively.
Lightcurve data for Europa has been very hard to interpret, so much so for a long time its period of rotation was in dispute (5 and a half, or 11 hours?) despite many observations<sup>[[#Zappala83|[8]]]</sup>. It has now been determined that Europa is a prograde rotator, but the exact direction in which its pole points remains unclear. The most detailed analysis indicates that it points either towards about [[ecliptic coordinate system|ecliptic coordinates]] (β, λ) = (70°, 55°) or (40°, 255°) with a 10° uncertainty <sup>[[#Michalowski04|[2]]]</sup>. This gives an [[axial tilt]] of about 14° or 54°, respectively.
It has been found that the star CV Aquarii found in 1934, was actually an incorrect misidentification of 52 Europa<sup>[http://www.aavso.org/publications/ejaavso/v28n2/103.pdf]</sup>.
It has been found that the star CV Aquarii found in 1934, was actually an incorrect misidentification of 52 Europa<sup>[http://www.aavso.org/publications/ejaavso/v28n2/103.pdf] {{Webarchive|url=https://web.archive.org/web/20060214091638/http://www.aavso.org/publications/ejaavso/v28n2/103.pdf |date=2006-02-14 }}</sup>.
== References ==
== References ==
# <div id="IRAS">[http://www.journals.uchicago.edu/AJ/journal/issues/v123n2/201433/201433.web.pdf Supplemental IRAS Minor Planet Survey]</div>
# <div id="IRAS">[http://www.journals.uchicago.edu/AJ/journal/issues/v123n2/201433/201433.web.pdf Supplemental IRAS Minor Planet Survey]</div>
# <div id="Michalowski04">T. Michałowski ''et al.'' [http://www.rni.helsinki.fi/~mjk/Micha.pdf ''Photometry and models of selected main belt asteroids I. 52 Europa, 115 Thyra, and 382 Dodona''], Astronomy & Astrophysics, Vol. 416, p. 353 (2004).
# <div id="Michalowski04">T. Michałowski ''et al.'' [http://www.rni.helsinki.fi/~mjk/Micha.pdf ''Photometry and models of selected main belt asteroids I. 52 Europa, 115 Thyra, and 382 Dodona''], Astronomy & Astrophysics, Vol. 416, p. 353 (2004).
# <div id="Michalak01">G. Michalak [http://www.edpsciences.org/articles/aa/pdf/2001/29/aa10228.pdf?access=ok ''Determination of asteroid masses II. (6) Hebe, (10) Hygiea, (15) Eunomia, (52) Europa, (88) Thisbe, (444) Gyptis, (511) Davida and (704) Interamnia''], Astronomy & Astrophysics, Vol. 374, p. 703 (2001) </div>
# <div id="Michalak01">G. Michalak [http://www.edpsciences.org/articles/aa/pdf/2001/29/aa10228.pdf?access=ok ''Determination of asteroid masses II. (6) Hebe, (10) Hygiea, (15) Eunomia, (52) Europa, (88) Thisbe, (444) Gyptis, (511) Davida and (704) Interamnia''] {{Webarchive|url=https://web.archive.org/web/20060307181251/http://www.edpsciences.org/articles/aa/pdf/2001/29/aa10228.pdf?access=ok |date=2006-03-07 }}, Astronomy & Astrophysics, Vol. 374, p. 703 (2001) </div>
# [http://www.psi.edu/pds/archive/lc.html PDS lightcurve data]
# [http://www.psi.edu/pds/archive/lc.html PDS lightcurve data]
# <div id="Dotto00">E. Dotto ''et al.'' ''[http://aa.springer.de/papers/0358003/2301133.pdf ISO results on bright Main Belt asteroids: PHT – S observations]'', Astronomy & Astrophysics, Vol. 358, p. 1133 (2000).</div>
# <div id="Dotto00">E. Dotto ''et al.'' ''[http://aa.springer.de/papers/0358003/2301133.pdf ISO results on bright Main Belt asteroids: PHT – S observations]'', Astronomy & Astrophysics, Vol. 358, p. 1133 (2000).</div>
# <div id="Sawyer91">S.R. Sawyer ''[http://adsabs.harvard.edu/cgi-bin/nph-bib_query?bibcode=1991PhDT.......105S&db_key=AST&data_type=HTML&format=&high=444b66a47d24766 A High-Resolution CCD Spectroscopic Survey of Low-Albedo Main Belt Asteroids]'', PhD thesis, The University of Texas (1991).
# <div id="Sawyer91">S.R. Sawyer ''[http://adsabs.harvard.edu/cgi-bin/nph-bib_query?bibcode=1991PhDT.......105S&db_key=AST&data_type=HTML&format=&high=444b66a47d24766 A High-Resolution CCD Spectroscopic Survey of Low-Albedo Main Belt Asteroids]'', PhD thesis, The University of Texas (1991).
# P. Schmeer and M.L. Hazen ''[http://www.aavso.org/publications/ejaavso/v28n2/103.pdf CV Aquarii identified with (52) Europa]'', Journal of the American Association of Variable Star Observers, Vol. 28, p. 103 (2000).
# P. Schmeer and M.L. Hazen ''[http://www.aavso.org/publications/ejaavso/v28n2/103.pdf CV Aquarii identified with (52) Europa] {{Webarchive|url=https://web.archive.org/web/20060214091638/http://www.aavso.org/publications/ejaavso/v28n2/103.pdf |date=2006-02-14 }}'', Journal of the American Association of Variable Star Observers, Vol. 28, p. 103 (2000).
# <div id="Zappala83">V. Zappalà, M. di Martino and S. Cacciatori ''On the ambiguity of rotational periods of asteroids - The peculiar case of 52 Europa'', Icarus, Vol. 56, p. 319 (1983).</div>
# <div id="Zappala83">V. Zappalà, M. di Martino and S. Cacciatori ''On the ambiguity of rotational periods of asteroids - The peculiar case of 52 Europa'', Icarus, Vol. 56, p. 319 (1983).</div>
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