Observers: Chris Lidman, Patrice Bouchet
Location: European Southern Observatory, La Silla, Chile
Date: August 5, 1995
This false-colour image of the newly discovered comet Hale-Bopp was obtained by Chris Lidman and Patrice Bouchet on August 5, 1995, UT 03:30, with the MPI/ESO 2.2-metre telescope at the La Silla observatory. It was registered with the infrared-sensitive instrument IRAC2 on a 256x256 pixel Nicmos3 detector and through a J-band filtre (wavelength centered at 1.5 micron) during an 8-minute exposure. The scale is 0.52 arcsec/pixel and the field of the image covers 2.2 x 2.2 arcminutes. The atmospheric seeing was 0.8 arcsecond. North is up and east is to the left.
Press Photo 21/95 shows the bright nucleus located in a well resolved dust coma with diameter around 2.5 arcsecond. There is also an approximately 1 arcminute long extension towards NW (upper right). It represents the beginnings of a dust tail, produced by the pressure of the sunlight on the dust particles in the coma.
At the moment of this exposure the comet was located in a crowded stellar field in the constellation Sagittarius (i.e., in the general direction of the Milky Way centre). The distance to the Earth was about 860 million kilometres; the distance to the Sun was approx. 990 million kilometres (corresponding to a location between the orbits of Jupiter and Saturn). The object was unusually bright for a comet at this large distance; a photometric measurement on this frame gives the integrated magnitude J = 11.2 through an aperture of 10 arcsec.
ESO Press Photo 21/95 may be reproduced, if credit is given to the European Southern Observatory. It was first published (in a rotated version) on the ESO WWW page on August 11, 1995.
ESO Press Information is made available on the World-Wide Web (URL: http://www.hq.eso.org/) and on CompuServe (space science and astronomy area, GO SPACE).
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