SSPM21. Summary of Recent New Moon Weekends at Wiruna
By Scortt Mellish, 1999
With the weather this year at Wiruna being so patchy it is very hard to do a specific post mortem on a particular month. So I have decided to just do a summary of some of the objects I have observed over the last couple of new moons at Wiruna.
As regular Wiruna visitors would know, if you get one good clear night you can do a whole years' observing in one go. But when there is only the odd 2 to 4 hours observing it is difficult to get motivated enough to begin a good observing session, especially when the dreaded clouds are hanging around like the plague.
Still, some good rewarding observing can still be had by the more persistent people, usually the ones who have their scopes out during rain hail or shine. You have to at Wiruna, as the weather has been known to clear at the drop of a hat. So it always pays to be vigilant, ready to man the trenches at a moment's notice.
Despite all the trials and tribulations, I have observed a fair few objects, so I will cover some of them in this post mortem with more to follow in later editions of Universe.
Here we have a regular little galaxy in Pavo. In the 16-inch at 210x mag. there is a nice sprinkling of stars to add contrast to the field. The galaxy itself is not particularly well defined, being a soft featureless smudge with the barest of cores visible only as a slightly denser central portion.
It is large enough though to be an interesting enough object to warrant some studies, especially with its much smaller and less conspicuous companion tagging along.
The halo of IC 4901 fades away from the denser central region, which suggests that the galaxy is much larger than what can be seen. I would suggest that IC 4901 is a face- on spiral galaxy. When I checked it on Mega Star it was quite large, then when I overlaid Real Sky on top of that it showed a lovely twirling spiral, face-on with the most vivid spiral arms that were very artistic in appearance.
IC 4901 would be around 5' x 4' in size and about mag. 13 in brightness. Its companion is known as ESO 142-51, and lies some 10' to the east-northeast. Diffuse and featureless ESO 142-51 is probably not a true companion, but the Real Sky photo shows some distortion in its odd shape, though I could not see any obvious filaments between it and the larger IC 4901. So whether the two are gravitationally bound is a question I cannot answer.
Visually ESO 142-51 is very diffuse at around mag. 14, and quite small at some 1' x 0.9' in size.
There is little hint of any core region, though it does seem to be a dense little galaxy. This is portrayed in the Real Sky photo, which shows a dense little ball with two measly little spiral arms protruding out. To finish off, these two galaxies in the 9mm Nagler at 210x make for interesting viewing. IC 4901 / ESO 142-51 R.A 19h 54' 23" DEC -58° 42' 50"
This nice little number in Pavo lies in a nice crispy star field in the 23' field of the 9mm Nagler at 210x mag. What we have in this object is the classic edgewise spiral. NGC 6810 is a very dense object in appearance and the central region is very bright for such a small galaxy. The whole object is quite compressed and very tight, with little or no wispy halo apart from the soft outer edges at each end of the object. This would be a very nice spiral if seen face on, as I would say that its core would be very luminous and dense, more so than the visual perspective seen here.
At some 3' x 0.8' in size it is fairly small, but on occasions these sorts of galaxies can be some of the more interesting ones, especially when there is more than one in the field.
The Real Sky photo does not show much more than can be seen here, other than a tight spiral tilted sharply to our line of sight. There are numerous galaxies in Pavo and this is one of the more curious ones that you can come across. At mag. 12.3 it should be visible in most telescopes. NGC 6810 R.A 19h 43' 34" DEC -58° 39' 21"
So what is so special about ESO 234-21? Absolutely nothing! What we have here is the usual run of the mill ESO Galaxy, with no particular claim to fame, having just been something that I thought might be worthwhile popping in for a look at. I do not usually prepare an observing schedule to any great extent, so when I get onto a page of a star atlas I am just as likely to observe anything that's on it. ESO 234-21 appears in the 16-inch at 191x as a ball shaped object of around 13th mag. Its core region is the predominant feature of this object as it is quite dense, but small. It has a faint outer halo that is very ghost-like but smooth and featureless. I would hazard to guess that this is a face on spiral of some description, with a very dense and probably active core.
The Real Sky photo does not give away much more than can be seen in the sketch. The picture is actually over exposed, which can make visual observing and sketching all the more rewarding, as sometimes the plain view with the eye can be just as good, if not better.
ESO 234-21 would be around 2' x 2' in size and all on its lonesome in the 18' field. This object was one of the first I observed with the new 10mm radian eyepiece, and on first impressions it would rate alongside the 9mm Nagler as one of the best for observing galaxies. ESO 234-21 R.A 20h 24' 20" DEC -49° 41' 04"