Click on the images for full size

M 57

NGC 6765

Min 1-46

St 4-1

K 3-27

Abell 46

All images were downloaded from the Digitized Sky Survey (Second Generation) and red and blue channels were combined to produce nearly proper colour images. The green channel was a combination of the red and blue channel. M 57 was overlayed an inverted image of my own to show the inner details of this nebula.

Planetary Nebulae in Lyra

In the fall of 2001 I found that I wanted to observe all planetary nebulae in the constellation Lyra. I do not remember the reason for starting the project, but I quickly found out that the planetaries in Lyra are very diverse. From the well known Messier 57 to the quite faint Abell 46.

Initially I found that there were seven planetaries, but it seems that one of them really is a galaxy catalogued in the LEDA database. In Hynes' book one more was listed, but this is an M star, so the count was six. When posting this article Brian Skiff suggested I include the new discovery Si 1-2, so the count then is again 7 nebulae. Using a 10" Dobson telescope (Orion XT-10) I've observed and drawn five of them, still missing Abell 46. I'm not sure if this last one is even possible with the 10" but I'll have to try. If nothing else, I've learned that the only way to see wether something is possible to see is to try it.

Well, here's the list of the objects mentioned:

This is partly from DSDB on Messier45.com and partly from the excellent book "Planetary Nebulae" by Steven Hynes. Colour images of all these nebulae are to the right.

Kohoutek 4-9 is the first one dropped, since it's an M star and with such an uncertain position it is impossible to spot in the DSS image. Not even a filter will help identify it.

Messier 57 we all know as the Ring Nebula and is one of the objects all amateurs have started with. The central star is not easy with a visual magnitude of 14.7v, but with pristine quality skies I've seen it with the 10". I've never tried the outer shell around M 57, and I'm not sure I will ever see it in the 10". Moving down the list from here will demand much more from the observer than M 57 do. Some are real tests in proper usage of maps and of observing skills.

The next planetary I observed was Minkowski 1-64, by some called "the other ring nebula in Lyra". However, observing this nebula will not reveal any ring structure. At least not under the conditions I observed it with. CCD images (this one by Odd Trondal) will show the ring (see also images on Google). The nebula is hard to locate. There are very few easy way points for star hopping. But using a UHC, UltraBlock, O-III or similar filter will quite easily reveal it in your field. The map in Hynes also helps, even if those maps tend to be a bit misleading at times.

The next was NGC 6765, which is more difficult than I though it would be. This has to be one of the most difficult NGC planetaries? It lies inside a triangle of stars and is very mottled in its appearance. I believe to have read that it is a bipolar planetary. It is very nice under good conditions and you will see a thick rod NE-SW with more nebulosity around it on both sides.

On the same evening I tried Kohoutek 3-27 which was much more difficult. Though it was a challenge to spot, it was quite easy to locate. Even with mediocre skies it was spottable as a very faint but defined round annular nebula using averted vision. The DSS image shows a nice little ring, hence you may call it "the third ring nebula in Lyra." I'll observe this one often.

Stephenson 4-1 (St 4-1 in Hynes, Sp 4-1 in Acker et al. 1992) was not difficult when conditions were good, but the first time I tried it I was very uncertain on identification. For the next try I had a better map and better conditions. It's only a stellar nebula right next to a brighter star. Using my UltraBlock filter removed all doubt. Guide gives a slightly erroneous position, but the position in the list above is correct.

Now it toughens up! Abell 46 is a faint planetary nebula with a total visual magnitude of 14.3v smeared out on an area with diameter greater than 1 arc minute. No easy task at all for a 10". The first and only time I've tried it I did not have a proper map and I had only a few minutes before it dropped behind a tree. So I do not have a positive id on this one yet. I did however believe to see something in the general area were it should have been, so I have a faint hope of spotting this one. With a good 12" or larger I believe it should be readily spottable.

Earlier I thought Kohoutek 2-6 to be a planetary nebula but checking a DSS image revealed nothing on the given position. However there was a nebulous object close by that looked somewhat like a planetary. In Guide this was identified as the galaxy LEDA 166555 with unknown magnitude. The DSS image shows a possibly skewed spiral galaxy. Even though this probably isn't a planetary, it should be fun to try and spot it.

Si 1-2 is a new addition. More on this nebula later! Suffice it to say this nebula is probably beyond any amateur telescope.

Summarising I would say that only Abell 46 (and possibly K 3-27) requires perfect conditions with a 10" telescope. The others are easier. I've also seen NGC 6765 in a C8. I would guess that the rest are possible with good telescopes from 6-8" and up. But this requires training and persistence. Remember that there is no shame in trying! I've seen Abell 4 in an uncollimated 10" when my friend claimed it would be impossible. He had barely seen it in a 16" Meade DS-16 a few minutes earlier.

Ranging the planetaries after difficulty I would give this list: M 57, NGC 6765, Min 1-64, St 4-1, K 3-27 and Abell 46.