The nucleus of comet Wirtanen

The image reveals a false-colour composite image of the nucleus of Comet Wirtanen (the point of light at the centre), recorded on December 9, 2001, with the FORS2 multi-mode instrument at the 8.2-m VLT YEPUN Unit Telescope. It is based on four exposures and since the telescope was set to track the motion of the comet in the sky, the images of stars in the field are seen as four consecutive trails.

The measured brightness and the fact that the image of the comet's 'dirty snowball' nucleus is almost star-like indicates that it is surrounded by a very small amount of gas or dust. The diameter of the nucleus is about 1 km and the distance to the comet from the Earth was ~534 million km.

The comet was located in the southern constellation of Sagittarius, rather low over the western horizon. The first two exposures were made through a standard R-filter and lasted 300s each (airmass 2.4 - 2.5); they were followed by two V-exposures of 250 (airmass 2.7) and 200 (2.8) seconds, respectively. The seeing at this low altitude was 1.0 - 1.2 arcsec. The measured magnitudes of the nucleus were R = 22.6 and V = 23.4 (both ± 0.1). North is up and east is to the left. The field measures approx. 2.0 x 2.0 arcmin 2 ; 1 pixel = 0.2 arcsec.

Herkunftsnachweis:

ESO

Über das Bild

ID:eso0206a
Typ:Beobachtung
Veröffentlichungsdatum:26. Februar 2002
Dazugehörige Veröffentlichungen:eso0206
Größe:512 x 490 px

Über das Objekt

Name:Comet Wirtanen
Typ:Solar System : Interplanetary Body : Comet
Kategorie:Solar System

Bildformate

Großes JPEG
514,7 KB

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Farben & Filter

SpektralbereichTeleskop
Optisch
V
Very Large Telescope
FORS2

 

Siehe auch