September 8, 2012: a night of planetaries

[michael.h.f.wilkinson]

Last night was clear, but the transparency of the sky was not that good, so bad actually, that I could not pick up the supernova in Bootes, and surrounding mag 13 stars, despite being able to see that a few nights ago with a gibbous moon. The humidity was very high indeed. After showing some guests the Ring, Dumbbell and the Great Hercules Cluster, I almost decided to pack the scope in, but after they had left, the haze seemed to be a bit clearer at zenith, so I decided to go on a little hunt for planetaries.

NGC 7027 was first. This showed up after a fairly easy star-hop south of zeta Cygni. It is a very odd object, very compact, with a very high surface brightness, and elongated with a 2:1 aspect ratio. It stood up to 205x magnification easily in the XW10. Using the UHC filter dimmed the stars but not the object.

NGC 7048 was just a bit further north. This was much harder to find. After many changes of EP, I noticed a very diffuse glow, similar to glare near one mag 9-10 star in the 31T5. It was not glare, however, as it was not symmetrical, and retained its brightness in the UHC filter in the 22 and 17mm Naglers. It reminded me of a fainter, smaller edition of the Dumbbell. I must go back to this under better conditions.

NGC 7026 followed. This is quite easy to find, just north of 63 Cygni. This star forms the base of an asymmetrical V, one arm longer than the other. Just to the inside of the longer arm lies a roughly circular glow, which maintains its brightness in the UHC filter. Easily spotted in the 17T4 at 119x.

NGC 7008 (the Foetus Nebula) was almost due north of the previous one. This was diffuse, elongated just to the north of a mag 10-11 star. Best seen in 22T4 with UHC.

After this the corrector plate started fogging up, so I called it a night. Nice haul in awkward conditions.

[acey]

Very nice report, thanks for that. Like you I had misty conditions last night and therefore aimed near the zenith, and I also happened to observe a PN in Cygnus that was new to me: NGC 6766 (aka NGC 6884, having been independently discovered by Copeland and Pickering). In my 12" it was exactly like an 11th magnitude star except for the fact that when I looked at it directly it faded considerably, like the Blinking Nebula but so much smaller that this was the only way I could tell what it was. A UHC filter confirmed it but didn't make it any bigger. An easy object if you know where to look - finding it in the first place was the tricky part.

[Double Kick Drum]

A nice collection of planetary nebulae there.

I did manage NGC 7027 but it was at the limit of my resolution. Very small but very bright.

NGC 7048 is on my to do list and will be a real stretch but the others are beyond my scope (at least from my back garden).

Clear skies!

[michael.h.f.wilkinson]

Very nice report, thanks for that. Like you I had misty conditions last night and therefore aimed near the zenith, and I also happened to observe a PN in Cygnus that was new to me: NGC 6766 (aka NGC 6884, having been independently discovered by Copeland and Pickering). In my 12" it was exactly like an 11th magnitude star except for the fact that when I looked at it directly it faded considerably, like the Blinking Nebula but so much smaller that this was the only way I could tell what it was. A UHC filter confirmed it but didn't make it any bigger. An easy object if you know where to look - finding it in the first place was the tricky part.

Thanks, Acey. I tried NGC 6884 yesterday, but I hadn't drawn up accurate maps with stellarium, so was rather lost amongst the myriad mag 11-12 stars. You really need detailed charts for these near-stellar PNs. Better luck (and preparation) next time.

[michael.h.f.wilkinson]

A nice collection of planetary nebulae there.

I did manage NGC 7027 but it was at the limit of my resolution. Very small but very bright.

NGC 7048 is on my to do list and will be a real stretch but the others are beyond my scope (at least from my back garden).

Clear skies!

Thanks, Martin. NGC 7026 should be OK for your scope, It has very good surface brightness. If 7048 is on the todo list, try 7008 as well, as I found it easier. In my experience, It is quite difficult to estimate the difficulty of a PN, was estimated brightnesses vary quite wildy in lists, and surface brightness is really the key. Quite often, the key is making a very good star chart, and comparing the views with and without UHC filter, as many PNs are nearly stellar. If you can see a mag 12 star with your scope, these stellar PNs at mag 12 are visible as well (but often not resolved. Once you know this, you can find dozens more.

Happy hunting

[acey]

Thanks, Acey. I tried NGC 6884 yesterday, but I hadn't drawn up accurate maps with stellarium, so was rather lost amongst the myriad mag 11-12 stars. You really need detailed charts for these near-stellar PNs. Better luck (and preparation) next time.

Yes, it's a devil to find. I used Great Atlas Of The Sky, which goes down to mag 12. TriAtlas C should have the same level of detail, which is the level you need. I located the exact spot and could see a star where the PN was marked, I looked directly at that star and it faded weirdly so I knew I'd got it. Apparently Pickering discovered it by using a diffraction grating or prism at the eyepiece. It's no big deal to look at and maybe not worth a great deal of effort but good luck if you feel like giving it another go. The ones you bagged are a lot more interesting!

[michael.h.f.wilkinson]

Yes, it's a devil to find. I used Great Atlas Of The Sky, which goes down to mag 12. TriAtlas C should have the same level of detail, which is the level you need. I located the exact spot and could see a star where the PN was marked, I looked directly at that star and it faded weirdly so I knew I'd got it. Apparently Pickering discovered it by using a diffraction grating or prism at the eyepiece. It's no big deal to look at and maybe not worth a great deal of effort but good luck if you feel like giving it another go. The ones you bagged are a lot more interesting!

I draw maps using the ocular plug-in of Stellarium, this limits the magnitude to the scope used. Interesting suggestion to use a grating. I wonder if the (quite affordable) star-analyzer EP gratings would work.