How is UGC NET cut off

The dwarf galaxy UGC 5470, also known as Leo I, is only 20 arc minutes north of Regulus, the bright main star of the constellation Leo. Leo I is very difficult to photograph because Regulus with its great brightness always shines into the picture and brightens the background at the bottom of the picture. I cut off the bottom of the image where Regulus shone in to get the image background reasonably evenly light.

UGC 5470 has a total brightness of 11.2 mag, which is spread over the stately size of 11.7 x 8.5 arc minutes. Even if it doesn't seem so at first glance, the galaxy is one of the spherical dwarf galaxies. At a distance of about 820,000 light years, it is one of the most distant companions of our Milky Way. Despite the great distance, it appears to be little more than a collection of single stars. But these are only the old, bright red giant stars. The mass of the stars are faint main sequence stars that provide a diffuse background. UGC 5470 has no more gas today, so that star formation has come to a standstill. In contrast, it experienced phases of violent star formation around 6 billion years ago and around 2 billion years ago. These were probably due to a close flyby of the Milky Way, so that the gas (and dust) still present at the time could clump together and form new stars.

As is so often the case when photographing the constellation Leo, a few minor planets sneak their way into the picture. In this case it is the 13.8 mag bright minor planet Hildburg that drew the bright trail, and a little deeper the 17.4 mag bright (19418) 1998FL49. Since I had to discard three frames towards the end of the recording due to tracking errors, the Hildburg trace in particular shows a visible gap. From this the direction of movement of the minor planet can easily be read, namely from southeast to northwest.

In order to have a guiding star, I unfortunately had to move Leo I to the edge of the picture. On the other hand, it brought a few more beautiful galaxies into the picture. When you click into the picture or here, the picture is displayed in full size and with the lettering of the brighter galaxies.

Date: 02/21/14, 10:52 p.m. CET

Optics: f = 750mm f / 5.4

Tracking: TVGuider with Watec 120N at 90mm f / 5.6

Total exposure time: 84 min (single images: 180 seconds)

Camera: Atik 460EX