Wednesday, April 6, 2016

Galaxies in Leo

Last weekend the weather cleared and the moon dwindled down to a waning crescent which left the skies clear and dark enough for my favorite objects, which are galaxies. Unfortunately, I am noticing that the sky glow from Mobile's getting steadily worse, galaxies that should be easily in reach of a 15-inch are either impossible from the club's darker sky site or very hard to see through my Dob. Nevertheless, the weather was pleasant, the humidity low and the brisk wind earlier that day gave way to light breezes after nightfall. Once I set up and collimated the telescope before darkness fell, I went to work on some old favorite objects such as the Crab and Orion Nebula, which looked spectacular through an Orion O-III filter and a 30mm Explore Scientific 82 degree eyepiece. Other objects I visited included the large and rich open cluster M-46 and it's planetary nebula, the emission nebula NGC-2359 known as Thor's Helmet, the globular clusters M-3 and NGC-2419, and the galaxies M-65, M-66 and NGC-3628, which are known as the "Leo Trio." Also examined were the galaxies NGC-2903 in Leo and M-51 along with NGC-5194 in Canes Venatici.

My main goal was to observe some Leo galaxies, including the very distant lenticular system NGC-3196, which is over 700 million light years away. Unfortunately, the seeing and the sky meant that galaxy will have to wait for a better night at a darker location. However, I had much better luck with the interacting galaxies NGC-3226 and 3227, which showed up easily at 227X. I could see how they are canted with respect to each other as well as the nearby galaxy 3222. NGC-3226 is oval with rapid brightening towards what appears to be a star like nucleus. NGC-3227 is more diffuse, larger and much more elongated with a bright inner region, It clearly is a spiral galaxy from its appearance through the telescope while NGC-3226 is an elliptical galaxy. NGC-3222 comfortably fit into the view at 227X with the other two. This E or S0 lenticular system I never noticed before until now, but it showed up as a lens shaped object with a brighter core. This galaxy is quite faint at a magnitude of 12.8, the other two galaxies shine at magnitudes 11.4 and 10.8 respectively. In one view, one can see a spiral, a flattened lenticular and an elliptical galaxy at one time. The interacting pair is 80 million light years away from us.

Another galaxy in Leo I was hoping to get a look at was the peculiar galaxy NGC-3239, but even though I was looking at it location it simply was not visible. Thus I will have to try for this one from a much darker area than the local club's observing site. I had much better luck with the NGC-3190 galaxy group which is also known as Hickson 44. Straight away the elliptical galaxy NGC-3193 and the inclined spiral galaxy NGC-3190 appeared in the field of view at 227X. With a few seconds more of scrutinizing the field, NGC-3185 soon appeared. Finally the very faint galaxy NGC-3187 revealed itself as a slash if light between three field stars. All four of these galaxies are related to one another and lie 60 million light years from Earth. NGC-3190 shines at magnitude 11.1 and shows an elongated oval shape in keeping with it's orientation with respect to our line of sight. I did glimpse a hint of its dust lane and saw it has a bright inner core. There is another galaxy superimposed on the outer reaches of NGC-3190 that shows up as a enhancement of the disk
s brightness known as NGC-3189. Very small and faint, it helps to make the dust lane more visible. NGC-3190 is also known as Arp 316 due to the very disturbed structure seen in photos. Nearby the elliptical galaxy NGC-3193 shines at 11.2 and shows a bright inner core and an oval outline. Also near NGC-3190 is the challenging barred spiral galaxy NGC-3187, which was seen only intermittently with averted vision. It shines at magnitude 12.7 but it's low surface brightness makes it look like a galaxy that is magnitude 13 or fainter. Finally the oval barred spiral galaxy NGC-3185 revealed a brighter core and a diffuse disk. It shines at magnitude 12 and shoed a brighter center surrounded by a fainter halo. This was the first time I noticed all five members of Hickson 44, though I did not know about the presence of NGC-3189.
Soon after observing Hickson 44, I tool the telescope down and drove home. Although the skies were not as clear as I hoped, they were much better than usual given the very rainy and cloudy weather during the past few years. I look forward to this weekend to look at more Leo galaxies as well as other objects.