When the comet is near the Sun in its orbit and is brightest, the nucleus warms up. Contrarily, when the comet is far from the Sun, it is a very faint object that can only be observed with the largest telescopes. It literally drowns in a sea of stars, rendering observations with Earth-based telescopes extremely difficult. The telescope followed the comet's motion and the stellar images in the field are therefore seen as trails. The field of view measures about 17 x 15 arcsec 2 .
North is up and east is left.
Comet Wirtanen is now approaching its farthest point in the orbit, the aphelion , and the coma is therefore expected to be thin, perhaps completely absent. It is thus a good time to attempt to observe the faint nucleus and to learn more about its properties. The telescope was set to track accurately the comet's motion - this went very well, demonstrating the excellent performance of the telescope optics, mechanics and control system, already at this early stage of the commissioning phase. It was located in a dense star field in the southern constellation Sagittarius. The white lines are the trailed images of background stars in the field.