A Quartet of Planetary Nebulae in the Moonlight

[John]

I've been using my ED120 refractor tonight with a bright full moon rising in the SE sky casting it's glow over much of that side of the sky.

The seeing was rather "ho-hum" so I gave up trying to split really close double stars and, recalling success with this scope in picking up the planetary nebulae NGC 6210 and IC 4593 in Hercules a few nights back, I decided to have a look for some more, despite the moonlight.

I started with the easy one of Messier 57 - the famous "Ring Nebula". It was easy to find but rather washed out. Still it's a DSO so that's a start.

Next I went to NGC 6826, the "Blinking Planetary" in Cygnus. A lot smaller than M57 and dominated by it's mag 10 central star but the small halo of nebulosity surrounding the central star was quite nicely defined at 150x. I was a little surprised that the blinking effect was minimal tonight with the nebulous halo constantly visible but I wasn't complaining - it looked rather nice and it seemed to be surviving the moonlight wash in the sky rather better than the larger M57.

Next up was my old favourite in Draco, the "Cats Eye Nebula" NGC 6543. Again well defined nebulosity with the characteristic oval "eye" form. Central star just about visible gleaming through as well. Pale blue tint to this one I thought.

Then I decided to go back into Cygnus and try for something that I'd not seen before. NGC 6884. This one is a challenge for the smaller scope. It is magnitude 10.8 but has a diameter of just 7.5 arc seconds so quite difficult to separate from a background star. With the help of Stellarium I was able to pinpoint a suspect at medium magnification then use 200x plus to examine it. A tiny and faint halo of nebulosity around a concentrated central area (but no central star) showed and a nearby triangle of magnitude 11-12 stars helped me to be sure that this was the planetary nebula correlating accurately with the Stellarium high power (and refractor flipped) view.

NGC 6884 is thought to be around 6,000 light years away, but maybe more, and quite a young object - thought to be around 1,000 years old maybe ?. It was discovered by Pickering in 1883 but he seems to have catalogued it twice, also noting this object as NGC 6766. Due to a mix up over co-ordinates, NGC 6766 was "lost" for over a century until an astronomer named Dave Riddle (apt name !) worked out that these were one and the same object !

Nice to be able to pick out this very small planetary nebula with the 120mm scope.

Clouds intervened so that's that for tonight but the session did demonstrate that planetary nebula are good targets for smaller apertures even with some moonlight in the sky and also that the smaller ones seem to get less affected by the "moonwash".

Incidentally, I did not feel the need to use a filter, of either UHC or O-III flavour. These particular little nebulae seemed to "pop" out quite well on their own this evening

 

 

 

 

[Sunshine]

Great string of targets! I made a note of these for future sessions.

[John]

1 hour ago, Sunshine said:

Great string of targets! I made a note of these for future sessions.

Thanks !

I have not really followed planetary nebulae all that much during my observing to date but I'm lately becoming aware that there are plenty out there and that they are worth seeking out, even with smaller aperture scopes.

Each one seems to have an individual character as well

 

 

[michael.h.f.wilkinson]

Lovely report. I love hunting planetaries, they are a highly diverse group of objects that often take a lot of magnification and survive moonlight if using a UHC or O-III filter. The brighter ones are about the only DSOs to show colour at the EP (the Saturn Nebula with Olly's 20" was a stunning blue green). Many really look like low surface brightness variants of Uranus and Neptune. One great weapon I have for the tiniest is the Denkmeier FIlter-Switch Diagonal, which allows you to slide a UHC or O-III filter in and out of the light path, causing the planetary to "blink" (actually, it is the stars that blink, and the planetary that stays roughly constant).

[Kon]

Excellent report and some really nice nebulas you got there; I will have to visit some of the planetaries in your list. Was the nearly full moon not an issue with the planetaries? Seeing last night was not great here with clouds coming in all the time.

7 hours ago, John said:

Next I went to NGC 6826, the "Blinking Planetary" in Cygnus. A lot smaller than M57 and dominated by it's mag 10 central star but the small halo of nebulosity surrounding the central star was quite nicely defined at 150x. I was a little surprised that the blinking effect was minimal tonight with the nebulous halo constantly visible but I wasn't complaining - it looked rather nice and it seemed to be surviving the moonlight wash in the sky rather better than the larger M57.

With regards to the NGC6826, with my 8" Dob I could see it 'blinking' with averted vision and a low power EP, but nebulosity was always visible with higher magnification. In your case you mentioned that you were surprised to be visible all the time; Is that because of aperture difference?

[Mark at Beaufort]

Well done John a good list of objects. I have been a bit lazy of late especially since we lost astro darkness. Most of my time has been solar observing. Sunday looks promising so I will try and stay awake.

[John]

1 hour ago, Kon said:

...In your case you mentioned that you were surprised to be visible all the time; Is that because of aperture difference?

Yes, I think so. I have observed this one with my 12 inch dob some years back and it didn't "blink" with that but I thought the smaller aperture might cause it to. I was observing at high power (150x plus) mostly though. I had forgotten how small NGC 6826 is - quite easily overlooked as a slightly bloated star at low magnifications. NGC 6884 even more so.

Apparently the mix up over cataloguing of 6884 / 6766 was caused by Pickering (or one of his team) discovering it in 1883 and then Ralph Copeland discovered it again in 1884 and designated it 6766 !

 

 

Edited May 27, 2021 by John

[John]

16 minutes ago, Mark at Beaufort said:

Well done John a good list of objects. I have been a bit lazy of late especially since we lost astro darkness. Most of my time has been solar observing. Sunday looks promising so I will try and stay awake.

Thanks Mark.

I must do some more white light solar observing now that there is some solar activity worth observing

 

[Epick Crom]

Nice report John! Planetaries are great to observe, each has its own character as you said. Happy you got some observations done despite the full moon

[Paul73]

Nice report John. The ED120 is truly a versatile scope!

I haven’t had a decent session on the nebulas for ages. Must get out under the moon rather than not bothering because I can’t see faint galaxies.

Paul 

[Jiggy 67]

Planetary nebulae are a bit of an obsession of mine, they can be beautiful and also challenging requiring an OIII or UHC filter to really bring them out. I have a few favorites, all the famous ones but amongst the best, but pretty low at the moment I think, are NGC7662, The Blue Snowball and NGC7009, The Saturn Nebula which actually does bare a remarkable resemblance to the planet

[John]

53 minutes ago, Jiggy 67 said:

Planetary nebulae are a bit of an obsession of mine, they can be beautiful and also challenging requiring an OIII or UHC filter to really bring them out. I have a few favorites, all the famous ones but amongst the best, but pretty low at the moment I think, are NGC7662, The Blue Snowball and NGC7009, The Saturn Nebula which actually does bare a remarkable resemblance to the planet

I have Lumicon and Astronomik O-III and UHC filters and they do work very well on quite a few planetary nebulae I agree.

Last night though I was happy with the unfiltered views

 

[Voyager 3]

14 hours ago, Jiggy 67 said:

Planetary nebulae are a bit of an obsession of mine, they can be beautiful and also challenging requiring an OIII or UHC filter to really bring them out. I have a few favorites, all the famous ones but amongst the best, but pretty low at the moment I think, are NGC7662, The Blue Snowball and NGC7009, The Saturn Nebula which actually does bare a remarkable resemblance to the planet

In fact after discovering Uranus , Herschel found them resembling Uranus and called them "Planetary nebula " . Cracking report John ! 

Edited May 28, 2021 by Voyager 3