Friday, 24 February 2017

Near but so easily overlooked

Some astronomical objects receive far less attention than they rightfully deserve. There may be many reasons for this, as for example that the object in question's too challenging. But that's a real pity because sometimes even the more difficult objects can turn out to be extremely rewarding. 

NGC4236 is a galaxy that resides in the tail of Draco, the dragon. It's a member of the M81-M82 group and therefore it lies only 11,7 million lightyears away from us. In astronomical terms, that's our backyard. Actually, NGC4236's only slightly smaller than our Milky Way and therefore it's by far the largest group member, significantly bigger than it's two famous neighbours. We also see this galaxy under a shallow angle, meaning that its light isn't dispersed over such a large area as is the case with galaxies we see face-on, like M33 for example. In short, NGC4236 has all that it takes to become one of the most popular astronomical objects. And yet, it isn't as it's surprisingly dim and contrary to smaller M81 and M82 it's unsuitable for small telescopes. The reason for this is unknown to me... I suspect that much of its light must be absorbed by a cloud of interstellar dust. Strangely enough NGC4236's located well above our galactic plane so its light doesn't have to plough through a lot of Milky Way matter, but it's the only explanation I can think of. All I can say is that it's a real pity because NGC4236 has so much to offer if you take the time for it. 

As I expected, this galaxy didn't "leap out" of the eyepiece at all when I turned my binoscope at it. The central bar was easily visible, but not more than that. Quite disappointing, but I didn't give up so easily. I tried to focus, used a bit of averted vision and let my eyes adjust fully to the telescope view. Little by little... I started to see more. The central bar wasn't homogeneous at all, but showed some interesting brighter knots. Eventually also most of the faint spiral structures slowly revealed themselves to me. What a beauty it was! A perfect barred-spiral galaxy under a perfect viewing angle... 

So please, next time that you're out and the sky's dark enough, give this one a try. I'm sure that you won't be disappointed!

But... wait a minute! I'm not finished yet! I didn't know this at the time of observation and discovered it only when I was doing some research for this blog post. But look on the right-hand side of the bright central bar. You'll notice that above the end of this bar there are two small, brighter patches. The middle one of which is... another galaxy!!! Yes! It's a dwarf galaxy that accompanies its big sister, just like M32 and M110 accompany Andromeda. But in this case PGC39369 lies right in front of the main galaxy and this makes it a thousand times harder to see. But it's there!!! I saw it, even without knowing it existed! 

How about that for a satisfactory emotion? Oh well... I know, I'm just a geek... :-)

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