ESO-Comet Wirtanen
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.Relevantní články
Wirtanen46P/Wirtanen je kometa s oběžnou dobou 5,44 roku, která byla objevena 17. ledna 1948 americkým astronomem Carlem A. Wirtanenem, 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. .. pokračovat ve čtení