NGC 6803 and NGC 6804

[WaveSoarer]

The night of 12/8/13 turned out to be extremely clear and Mrs WaveSoarer and I went out to see if we could spot any of the Preseids meteor shower. I also set up the telescope to do some DSO observing. After picking out a few of my favourites I went to look for NGC 6803 (the Ghost of the Moon) and NGC 6804, which are planetary nebulae a good deal smaller and dimmer (Mag. 11 and Mag. 12 respectively) than I'd previously managed to find.

I star hopped from Altair to mu Aq1 and then up to NGC 6804. Although this is the fainter of the pair it was surprisingly easy to find as it's set between the mag. 8.85 HIP 96056 and another Mag. 9.25 star. It's distinctly fuzzy and quite unmistakeable. Happy with seeing this I then moved on to NGC 6803. Although the brighter of the pair, this proved more difficult as it's much smaller than NGC6804 and has a quite stellar appearance. I could pinpoint its location with Stellarium but I couldn't convince myself that I wasn't just looking at another star in the right vicinity. I later continued looking at other DSOs while also trying to catch up with Mrs WaveSoarer's impressive total of Preseids - she got nearly twenty in the half hour she was outside.

I did a little more reading up on NGC 6803 the next day and as the evening also turned out clear again I set up the telescope and I had another go. One tip I found on the web was to get set up on the position of the nebula and then place an OIII filer in front of the EP. By switching quickly between the filtered and unfiltered view then it should be possible to pick out the nebula as this will not dim significantly while the neighbouring stars become much less bright. I was cautious to avoid getting the filter dirty but, sure enough, this technique did actually work and it was almost immediately apparent which of the candidate points of light was the nebula. With the position clearly indicated the nebula did take on more of a fuzzy appearance at higher magnification - though the perception of fuzziness may have been more wishful thinking on my part. By contrast NGC 6804 was much more obvious and I took time to view it at reasonably high magnification. I used my 5 mm EP, without the OIII filter, and found that it had a fairly mottled appearance with just hints of small points of light with averted vision.

It was rather pleasing to observe this pair of planetary nebulae and NGC 6803 was certainly quite a challenge.

[cotterless45]

Lovely report full of the sort of detail to enable observers to put some trousers on and leap out to view these beauties,

Nick.

[andrew63]

Enjoyed reading your observations - it makes you realise just how much there is to see...

andrew

[WaveSoarer]

Thanks Nick. These more challenging objects can be very satisfying once you've found them.

[WaveSoarer]

Thanks Andrew. There is a lot to see indeed.

[acey]

Well done on seeing these. I attempted both in September 2009 with my 12" f4.9 Flextube at a dark site and only managed NGC 6804. Here's what I wrote then:

NGC 6804

Asymmetric, star at northern tip, somewhat fan-shaped from there. 2 or 3 other stars involved, seen with averted vision at x250 (one of these is the central star but I couldn't hold it with direct vision). UHC filter makes the stars disappear and gives a generally poorer view (at x150).

NGC 6803

Luginbuhl and Skiff's Observing Handbook says this object is stellar in apertures less than 25cm (10"). I hunted with all magnifications, with and without UHC, but there are lots of stars in the field and I couldn't find it.

Obviously I need to try that one again. I'm intrigued that it should be nicknamed "ghost of the Moon". The famous "Ghost of Jupiter" got its 19th-century nickname because it has about the same apparent diameter, but NGC 6803 is the sort of view of the Moon that you'd get from Pluto! Clearly a name that came from somebody looking at a photo rather than the real thing.

Edit: I just Googled it, and the only reference I can find to a "ghost of the Moon" is NGC 6781, also in Aquila, and a much easier target. I viewed it with an 8" in September 2003 and from what I wrote then I can see that the nickname is appropriate: "Very pale and ghostly, but large enough to be conspicuous at x60. UHC greatly enhances contrast, but revealed no detail I could see. Hardly visible at x150 without filter; with UHC I lost it altogether."

[WaveSoarer]

Thanks for that Acey. A very good report and much in line with what I observed - though the extra aperture will certainly have helped picking out features within NGC 6804. I'll now go looking for NGC 6781 when I next get the chance.

[cotterless45]

Yep, got NGC 6781 at mag. 11.1, really ghostly !

Other planetary nebulae of interest here ;

NGC 6741

NGC 6751

NGC 6788

NGC 6807

Aquila is very well placed at the moment and it's worth having a shot even at some fainter ones if the seeing is good. The other night I was surprised to see a mag 14 planetary. Not surprising that I forgot to record which one.

Too busy putting my socks back on, which had blown off in shock !

Nick.

[WaveSoarer]

Great stuff as ever Nick.

[WaveSoarer]

Despite the moon being just beyond first quarter I had a hunt for NGC 678, the real Ghost of the Moon (please forgive my misidentification of NGC 6803). After a bit of a struggle with the fairly bright viewing conditions, I managed to pinpoint its location in the finder and I could then view it with my 15 mm EP and the OIII filter. It sits on the long edge of an isoceles triangle formed by three ~9.5 mag stars which neatly fitted the field of view. The nebula had the appearance of a faint ring with averted vision and gave me the impression of a fainter but rounder (less elliptical) ring nebula. I think that the sky would need to be moonless to get the best view though. I was really pleased to find it nevertheless.

[WaveSoarer]

Doh! That should be NGC 6781. I'll get things right eventually, promise.