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European Southern Observatory

A near-parabolic orbit with perihelion passage in April 1997
25 August 1995

Harvard's IAU

Comment on the 1993 Observation of C/1995 O1 (Hale-Bopp), by Brian G. Marsden
21 January, 1996

Harvard's IAU

PRESS INFORMATION SHEET: Comet C/1995 O1 (Hale-Bopp), by CfA
16 February, 1996

A single, apparent image of the comet was found by astronomer Robert H. McNaught of the Anglo- Australian Observatory from a wide-field photographic plate taken in late April 1993 (when the comet was about 13 AU from both the sun and earth). This observation has strengthened the orbital calculations by greatly extending the arc of observation. It allows one to say that the comet has an orbital period of a few thousand years and extends out to some ten times the distance of Neptune at its furthest point.