Planetary nebulae, EEVA-style

[Martin Meredith]

Great haul of PNs. NGC 2392 is really special as is the Medusa, hanging there in space like a ghostly crescent.

I thought I'd visited NGC 2392 in colour but apparently not (blue with a touch of pink?). Here's a shot showing far less resolution than yours.This is a single sub, possibly too long at 30s; stacking didn't really help (produced a smoother result, but not what is needed here).

Its impressive how you can get great results with a 15" scope and relatively small sensor (by today's standards). What system are you using for tracking?

Martin

 

[Bill S]

I could not resist having a look at my colour (LRGB) Jocular snapshot of NGC 2392. Tried out the various stretch options. With faint distant galaxies I usually settle on hyper but this object is a lot brighter (only 5 second subs). Anyway, I settled on either gamma or log. Log is the one below. Brings out a bit of detail. Mike JW's in mono with the bigger scope and more pixels shows more though. Always good to see different shots and compare.

[Martin Meredith]

Very good to see this planetary in colour. The electric blue is spectacular as is the slightly pink 'eyebrow' at the right in your shot. 

I often use log for bright PN and have even been known to use linear!

Martin

[Mike JW]

Last night (16/02/21)  I took a look at three more PNs in Gemini. They are rarely visited and I struggled to find out any information on them, so if anyone finds out something about them please add it into the thread.

First up K3-71 - a very distant PN lost in a lovely star field. Lost being the operative word - if it wasn't for Jocular plate solving the subs I would have had to spent ages checking to see if the star field matched - probably impossible.  It is there in the wide field shot but you have to know where to look. Just above centre and tiny.

 

 

The close up below shows hints of detail - is it bi-polar?, dark line through it.

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

NeVe 6 was easy to pick up in a crowded star field.  I saw somewhere the comment  'probably a PN'.  Latest data suggests it is a H11 region and not  a PN.

 

J 900 - at first I could not spot it until I realised it was  the rather bloated star. I guess the give away is, for its size it lacks diffraction spikes. Colour might pick it up easier?

https://www.nasa.gov/mission_pages/hubble/science/j900.html  - worth a look

Edited February 17, 2021 by Mike JW

[Martin Meredith]

Really interesting to see what these look like with your 15". I imagine they are very rarely observed, as you say. I've tended not to add the more obscurely-named PNs to my observing list but maybe I should. I've tried a few Ms and Ks in the past without a lot of joy. I'll definitely check out J 900 in colour next time I'm out. NeVe 6 doesn't look like a PN. I've seen at least one Arp that looks similar to that fuzzy nest.

Platesolving comes into its own for PNs. Browsing through some of my captures over the summer it has been interesting to see where some of them actually are (or missed in at least 2 cases).

Martin

 

[icpn]

I spoke with Mike about these. NeVe6 is an HII region not a PN. J900 may not be well known in some circles but it has been well known amongst visual PN observers for a long time. It even made the Webb Soc Deep SKy Observers Handbook  Vol 2 in 1978, along with J320 in Orion. It seems a shame that so much literature is ignored just because it is not  on the internet now. People need to look back at older references..

[Martin Meredith]

Here are a couple of many PNs I observed last night as part of a 4 hour session, making up for lost time. Both were discovered by William Herschel and, although I didn't realise it at the time, both are distinguished by astrophysically-interesting central stars.

First, the blue-green gaseous glow of NGC 1501 in Camelopardalis, which has a complex filamentary envelope in 3D that is well seen on the Hubble image. One can just about make out a few strands in my image. The easily visible central star is mag 14.3 CH Cam, an extremely rapidly-pulsating ZZ-type variable (not looked up what the ZZ means yet) with an amplitude of 0.1 mag in around 20 minutes, so is something that is worth observing over an hour or so. The PN itself is less than an arcminute across.

WH discovered NGC 1501 in 1787.

 

The second Herschelian PN of the night is NGC 2440 in Puppis. In contrast to NGC 1501, which has a healthy (for Northern observers at least) declination of over 60 degrees, this one is at around -18 degrees but just about clear of the murk for me.

 

 

Its central star is regarded as one of the hottest known white dwarfs. The central star is not visible here, at magnitude 17.7, being buried in the central pair of lobes.

WH discovered NGC 2440 on this very day, 4th March, in 1790. 

I must say that when I started this thread I was not sure whether EEVA and PNs were a good match, but I am now totally won over. My standard approach these days is a minute each in LRGB in 15s subs and this works well for many PNs -- except for most of the Abell PNs I've looked at! 

cheers

Martin

 

Edited March 4, 2021 by Martin Meredith

[Mike JW]

Hi Martin,

I have just checked my records for the big Dob - I never got around to viewing 1501 visually, so good to see it and in colour. I have just had a look at what ZZ means -'non radially pulsating' - which I think means one part of the star is expanding whilst another part is not (or contracting) - need to read some more.

2240 - too low for a worthwhile view for me. https://esahubble.org/images/opo9935e/ - great image and some more detail

Mike

[Bill S]

Hello Martin

A great couple of snapshots there. Beautiful and interesting objects. The central stars are fascinating. I had not heard about pulsating white dwarf stars before. More to follow up.

Good to hear your standard approach for getting reasonable observations for many PNs.

Bill

[Martin Meredith]

Thanks Mike and Bill. I was fortunate to have another lengthy session last night during which I observed 7 PNs which I need to sort through (since 3 of them are Abells one can predict a few failures to see much although Abell 21 is glorious). One of them was Jonckheere 900 (J900) that Mike posted a while ago. Here it is in colour -- distinctly greenish and slightly oval (I am always concerned about tracking when I see this shape).

 

[Mike JW]

J900 in colour - so much more obvious than my mono shot - nice.

Mike

[Martin Meredith]

Here's one that I found near impossible to see last night: Abell 33 in Hydra, discovered by George Abell in 1955. The labelled blue marker is in the centre of the PN and the near circular boundary just about intersects the bright star (mag 7.2 HD 83535).

 

The PN might just be easier to see in this negative image -- at least, I can convince myself that it is there. I think some new stretch techniques are called for to enhance local contrast... The central star, obscured by the blue circle in the image above, is very clear at mag 15.5/15.8 depending on the source.

 

Abell 33 has a listed magnitude of 12.9 but a surface brightness of 24.8, which just goes to show that magnitude is nearly meaningless for these extended objects. In contrast, as a bonus, there is a mag 17.9 quasar marked at 10 o'clock in the upper image (though the marking is a little faint -- still working on the automatic annotation).  This is pretty distant with a redshift of 1.9 (>8.5 billion LYs). It doesn't look clearly detected in the upper image but is definitely very obvious in the monochrome zoom.

 

I completely failed to see Abell 18 in Monoceros, also discovered by Abell in 1955 (Abell was one of 4 discoverers of the objects that ended up in his catalogue). This has an even lower surface brightness of 25.9 and a listed magnitude of 17.0, so it was crazy to even look (except I didn't check beforehand). Even the central star is shining at a dazzling magnitude of 20.9...

Nor did I spot Abell 31 in Cancer (SB = 26.6) although I did see the central star (no much by way of compensation...)

Unfortunately I didn't have my Oiii filter in the wheel but I plan to revisit these at a later date with the filter.

Next: more Abells...

Edited March 5, 2021 by Martin Meredith

[Martin Meredith]

Now to one that can be seen without narrowband filter: Abell 21 in Gemini. I've turned the saturation up on this one not only for the sake of the nebula itself but to better appreciate the very blue central star that looks like a hot pixel. All I can find on this is that it is mag 16.0 and type D0Z. 

I did happen to have an H-alpha in my filterwheel so I took a quick look using a L-H-alpha combination with the saturation turned up to a lurid level (must do something about those pink stars):

 

 

[Martin Meredith]

And here are the remaining 'blue period' PNs I looked at over these last two nights (relative scales not preserved). These are mainly 1 minutes (4 x 15s subs) in each of RGB and L. The faint outer wings of NGC 2371 are visible in the colour shot but more easily seen in the negative view. Thanks to Bill S's image above for motivating me to look at this strange object. I also find the delicate 'sliced lemon' structures of NGC 1514 and 2242 very appealing for some reason.  

[Bill S]

Martin - what a fine set of observations. I’ll be adding some of these to my lists for future observations and background reading. 
 

Some clear skies would help...

[roelb]

Thanks Martin for those fine planetary objects and your descriptive comments.

I add them also to my "planetary to do" observing list.

 

[Mike JW]

Martin - inspirational. It makes me wonder what details I would get if I opted into colour using the 15.

Thanks

Mike

[Mike JW]

IC 1747 in Cas is a small PN and easily missed in a crowded star field. (centre of the wide shot). Some folk call it the Holepunch Nebula - beats me as to why this name!.  The shot is with my 7" scope  and would be of more interest in colour , bigger scope and probably a small pixel camera.

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Close up indicates it may well be bi-polar.

 

Mike

[Mike JW]

PK69+3.1 (K3-46) in Cygnus is not an easy target and on my first attempt I failed to get it. Last night conditions were good enough to give it a go - success. It lies about 7,200 lyrs away and is thought to be about 20,000 years old. It has an hour glass shape with a bright equatorial ring. It is expanding much faster in the polar direction. It is easily missed in the concentrated star field - see my wide field image.

North is up in both views.

 

 

 

 

 

 

 

 

 

 

 

 

 

Mike

Edited June 2, 2021 by Mike JW
poor grammar again

[Martin Meredith]

Fascinating object, whose interpretation is much aided by the diagram. Definitely a candidate for the Spot the PN competition that we don't yet have.... 

I've only got one supposed observation of a 'K' object, K 1-13, which remains invisible in my shot (without filters).

Martin

Edited June 2, 2021 by Martin Meredith

[Martin Meredith]

I had a chance to observe a further 8 PNs last night, all in Cygnus. They came in various shapes and colours, and some of them are very hard to spot indeed in the 'wide' field images (0.34x0.44 degrees here).

Here's NGC 7026, which is a very pale pinky-blue. The bright star in the image is 63 Cyg, mag 4.5, which is double (sep 15") and slightly variable.

 

A closer  look at the PN shows two bright parallel bars, joined by wispy material at each end (the Hubble shot provides quite a bit more detail ;-). I also included the beautiful unequal double, Burnham 158, at the right of the shot, mags 7.5 + 12, sep 11" and turned up the colour saturation to better appreciate the contrast. 

 

 

Martin
 

 

[Mike JW]

Colour makes such a difference. I have this PN on my list for the 15.  As you know I just love a double star and great to clearly see the colour contrast in Bu 158.

Mike

[Mike JW]

PN:  M 2-54 in Lacerta.

Not much to say - if it wasn't for Jocular plate solving I would not have been sure I was in the right area. Really needs colour to locate it.

 

Mike

 

[Mike JW]

Abell 72 (PK 059+18) in Delphinus is tricky even in a large telescope (can be picked up in a 24" scope in good conditions). It lies about 3700 lyrs away and is about 3lyrs across. There are some beautiful images on the internet which pick up much detail. I was pleased just to get a hint of it.  The CS star is visible in my shot.  This PN is likely to be Bi-Polar. The obvious adjacent galaxy is 200 million lyrs away.

Mike

[Mike JW]

Last night I was wandering around Andromeda and I spotted  K 1-20  (PK110-12.1) in the Jocular DSO data base. At mag 16 I knew it was going to be a challenge so I experimented with different sub times. See below. It looks like I picked up the central star and a hint of structure. I have not been able to find any information about it. 

Mike