Evropská jižní observatoř

Kategorie: Sluneční soustava, Zpět na celou fotogalerii.

Popis (v anglickém jazyce):

This negative photo shows the faint image of periodic
comet Halley (in the circle) at the record
heliocentric distance 18.82 AU (= 2,820 million km,
about the distance of Uranus). It was obtained with
the SuSI CCD camera at the ESO 3.58 m New Technology
Telescope (NTT) during the night of January 10--11,
1994.

Nine individual exposures, each lasting 25 minutes,
were used to produce this picture. They were cleaned
to remove various sky and instrumental noise, shifted
according to the predicted motion of the comet and
then co-added. This ensures that all recorded light
from the comet is concentrated in one place. At the
same time, the images of the other objects that do
not share the motion of the comet, are not superposed
and will therefore be seen as long trails. The
non-uniformities of these trails arise because of
varying sky conditions and also due to the time
intervals between the individual exposures.

In addition to the comet, the picture contains the
images of three very different types of objects:
stars with relatively sharp trails (e.g. the
comparatively bright one, just below the comet
image), several extended (diffuse) galaxies, and an
artificial Earth satellite which happened to cross
the field during one of the exposures (its trail
extends from the middle of the left edge to the lower
edge).

The measured magnitude of P/Halley is V = 26.5
+-0.2. The position in the sky is less than 1 arcsec
from that predicted on the basis of the comet's very
well-determined orbit.

Technical information: The CCD frames were cleaned of
cosmics and flat-fielded, but they were neither
filtered, nor smoothed. Total exposure time: 13,500
seconds. The seeing varied from 0.6 - 0.9 arcsec. One
pixel = 0.13 arcsec. Field size: 310 x 430 pixels or
40 x 56 arcsec. North is up and East is to the left.

Odkaz na další informace na www.eso.org (stránka v AJ)