Wirtanen
46P/Wirtanen je kometa s oběžnou dobou 5,44 roku, která byla objevena 17. ledna 1948 americkým astronomem Carlem A. Wirtanenem (jehož jméno nese), při jeho pozorování na Lickově observatoři. Kometa náleží do Jupiterovy rodiny komet s krátkoperiodickým oběhem a průměr jejího jádra byl stanoven na cca 1,2 km.
Kometa 46P/Wirtanen měla být původním cílem sondy Rosetta, avšak kvůli technickým problémům při vypuštění sondy byl vybrán náhradní cíl v podobě komety 67P/Churyumov-Gerasimenko.
Nejbližšího dalšího perihélia dosáhne 12. prosince 2018.
Externí odkazy
Obrázky, zvuky či videa k tématu Wirtanen na Wikimedia Commons - O 46P/Wirtanen na stránce Hvězdárny Barona Artura Krause
- 46P/Wirtanen Pozorování a perihélia (anglicky)
Média použitá na této stránce
Autor: ESO, Licence: CC BY 3.0
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.