Planetary nebulae, EEVA-style

[Bill S]

I had another look at  NGC 2022 in Orion about a week ago. It's OK but nowhere near the detail Martin got in his shot on 14 January. (Martin, do you think this is this largely because you are using the ASI 290MM whereas I am using a Lodestar?)

I did find that I could not a get a stacked colour image at all to start with but the guidance to shuffle the subs solved that problem.

 

Anyway it is a pretty colour.

 

Bill

[roelb]

Those are my NGC 2022 images:

Evo 8 @ F/4.9     Lodestar X 2 Mono     2 x 30 s

Evo 8 @ F/4.7    ASI290MM    11 x 8 s   BIN 2

 

[Mike JW]

Bill - still good to see colour for 2022 but as you indicate it lacks the detail.

Roelb - the detail is there, in the second shot, just need to zoom in.

I have put it on my target list but so few clear spells.

Mike

[Martin Meredith]

Lodestar or ASI 290? Good question! I think perhaps seeing was better when I took my short of NGC 2022.

What's is certainly true is that the ASI 290s smaller pixels are much better suited to my focal length than the Lodestar and this really helps for PNs if the seeing supports it. The downside is fretting about gain. The last few sessions I've left it on unity gain (110) which I think will be my default setting until I understand what if any advantages of upping or downing the gain are. 

[Bill S]

Martin - I'll watch your experience with the ASI 290 with interest!

Meanwhile I thought I would try something different with lenses. I normally use a 0.5x reducer to make my scope faster than its normal f/5. I thought I would try going the other way. I replaced the reducer with something called a Magnimate Magni-Max. It is something I bought years ago to go with a binoviewer  so that I could reach focus. It's more or less a Barlow but it has a 1.25 inch thread and so I screwed it into a short C/CS adaptor on my Lodestar. It's marked 1.6x but due to the short adaptor I found it was more like 1.45x and made my scope set up about f/7.

This gave a bit more detail in NGC 2022.

 

Of course I then wanted to look at some other planetary nebulae. I think these have been shown earlier in this thread by Martin and others.

I liked NGC 1514 a good outer ring and really quite large.

This Eskimo Nebula (NGC 2392) is an old favourite but I managed to see a bit more with the increased magnification so was worth a look.

NGC 2346 was a break from the blue.

A return to blue came with NGC 2371. The outer lobes show up faintly. It does look a bit like a sweet in its wrapper. Hence its nickname The Candy Nebula. (Also The Bow-tie Nebula.)

 

Wikipedia tells us that NGC 2242 was thought to be galaxy until 1987 when it was shown to be a planetary nebula. I find that difficult to believe. But here's the paper (or at least the first page):

https://www.jstor.org/stable/40678863

I'm sufficiently old that 1987 does not seem very long ago.

And finally here's one that is not blue and would perhaps have been better with less magnification. This is also called the Medusa Nebula. It's an old planetary which is why it is so large - the shell has expanded so much. It was regarded as a supernova remnant at one time but shown to be PN in 1971.

An interesting night's viewing.

Bill

 

Edited February 7, 2022 by Bill S
Corrected name of supplementaty lens to 'Magni-Max'.

[Mike JW]

Bill/Martin Interesting to follow your experimentation. Visually on the nights that allowed for it, then to up the magnification on PNs, detail would be revealed - so Bill going to f7 is probably the right approach.

Mike

[Cosmic Geoff]

I have read this thread with interest as I have been imaging a number of the same PNs and recently have tried re-imaging a number of PNs recorded with 102mm f5 achro and ASI224MC camera, this time using a CPC800 (8" f10 SCT) and ASI224MC.

Examples of NGC 2392 are attached. These are single images (for other objects I achieved live stacked images) The more populated image is taken with the 102mm.  The images taken with the 8" SCT generally show more detail of these very small objects but the exposures are much longer.  The results seem limited in exposure by the Bortle 6 sky-glow and in resolution by the bad seeing.  For instance I have not been able to image NGC246 (pictured in this thread) at all.

I have not decided what combination of telescope and sensor works best or what upgrade of equipment might be worth considering.

[Martin Meredith]

Hi Geoff

Is your 8" f/10 scope reduced or operating at its native focal length (and if so, are you guiding?). If native, you might also have issues with the small FOV (0.14 x 0.1 degree) for that combination in terms of getting enough stars to stack (or platesolve, if you do that). Under the right circumstances (great tracking and seeing) there are PNs that ought to turn out well with that setup, but much of time I imagine it will be a struggle.

Martin

[Cosmic Geoff]

1 hour ago, Martin Meredith said:

Is your 8" f/10 scope reduced or operating at its native focal length (and if so, are you guiding?). If native, you might also have issues with the small FOV (0.14 x 0.1 degree) for that combination in terms of getting enough stars to stack (or platesolve, if you do that). Under the right circumstances (great tracking and seeing) there are PNs that ought to turn out well with that setup, but much of time I imagine it will be a struggle.

Noted. I am thinking that I may buy a 0.63 focal reducer.

[Mike JW]

Hi Geoff,

I have used a C9.25 and a C11 for EEVA and found working at f6.3 (i.e. using a focal reducer) worked well for capturing all sorts of DSOs including PNs. I did once try the f3.3 reducer but that introduce too much coma. 

Mike

[Cosmic Geoff]

I have acquired a f6.3 focal reducer and tried it out last night. First results indicate that it is a very worthwhile purchase. Images of the same PN with three different setups are shown below. 

Unfortunately the extra length of the reducer causes the imaging train to hit the forks base at altitudes above 70 degs - a major problem. I will have to figure out a workaround - can I find objects without the flip mirror diagonal while maintaining the backfocus in the recommended range, or find a more compact adaptor to connect the flip mirror and reducer (that would be T2 to SCT thread)?  

 

Edited February 12, 2022 by Cosmic Geoff

[Mr Spock]

Great looking planetary, nicely imaged too 👍

[Mike JW]

Hi Geoff, progress indeed. I once used  a flip mirror and for me it was a waste of time. I soon sold it. I found/find that if I align accurately and two star sync, then sync to a known star or DSO in the region of interest then the DSOs I am planning to hunt down are always in the fov. If I then go off to a different area of the sky I will GOTO a bright (ish) star in that region, sync to it, then maybe head to a bright (ish) NGC to check the sync and then head off to the really tricky targets that interest me.

Have fun,

Mike

[Cosmic Geoff]

On 15/02/2022 at 19:15, Mike JW said:

I found/find that if I align accurately and two star sync, then sync to a known star or DSO in the region of interest then the DSOs I am planning to hunt down are always in the fov.

Good suggestion. I intend to try doing without the flip mirror at the next observing opportunity. 

[catburglar]

Been tinkering with my EEVA setup over the last few weeks- between storms.- trying out an F3.3 reducer with the ASI290 mini (bin x2) in a 10inch LX200. Current spacing seems to give a focal length of about 750mm instead of the native 2500mm and a sampling rate of 1.6 arcsec per pixel.I got a couple of hours tonight to get the backspacing and focus sorted...although I've still got a little bit of work to do on collimation and sorting out some tilt (vignetting/coma is a little excentric- more pronounced towards the lower right (although cropped in this image).

I chose to look at the Eskimo as a first target because it was well placed away from some local light pollution. I might look to add in a filter wheel to get some colour in the mix, but might have to sacrifice the zero image shift microfocuser or the backspacing will be too long.

Edited February 22, 2022 by catburglar

[Mike JW]

I will be interested to see if you get on well with the 3.3 reducer - I never properly succeeded - way too much coma and as you have discovered tilt is also critical.

Mike

[catburglar]

At present I’ve got a usable FoV of about 0.4 deg x 0.24 deg - but if I can sort out the tilt I think I’ll get a bit more width because the left side of the FoV shows minimal vignetting out to the edge and a few flats should hopefully sort it out. 
 

I could also reduce the spacing a little to bring it closer to 800mm fl, but I’ll still lose FoV and I won’t gain much from the increased sampling rate. 
 

I think what I have is quite usable if I can’t get it any better- so I’m nearly ready for galaxy season.

[Cosmic Geoff]

Further to my previous post, I dispensed with the flip mirror assembly, using a star diagonal to give some spacing.  It is fairly easy to manage without it. The widened field of view also helps... Using Celestron's 'Precise Goto' the 'PG' aligning star sometimes appears in the camera field, and if it doesn't, the 9x50 RACI finder can be used to correct the aim. 

I also found out that it was possible to do a plate-solve on a rich starfield with this setup, with Sharpcap/ASPS

NGC2440 was quite low, so low that the 'precise Goto' star was behind a building and I had to manage without.

[Mike JW]

Great to see your progress at sorting the set up.  As my C9/C11 scopes were equatorial mounted I dispensed with a diagonal as well but that is not an option for you on a fork mounted scope.

Have fun,

Mike

[Mike JW]

Abell 30 is real challenge. I was only just able to detect this PN. It is however a fascinating object to read up about. It is a rare type of PN that has been reborn. It also has a binary central star. - https://www.nasa.gov/mission_pages/chandra/multimedia/nebula_abell30.html

Mike

[catburglar]

I had a go at a couple of planetary nebulae last night...before the moon rose too high in the sky.

I took a shot at Abell 21. I was surprised to get so much detail in this one given it's relatively large size and correspondingly low surface brightness. There are even fainter filaments in the area to the top right of this shot, but I couldn't capture them last night. I'd also like to try and get a bit of colour in this as well because the image by @Bill S shows both the red colour of the nebula and a couple of nice golden orange field stars which makes an attractive contrast. As Bill notes- this was thought to be a supernova remnant until recently (I tend to use the term recently for any new knowledge that's accrued in my lifetime, but I should probably rethink that definition since I'm mid-way through my 6th decade 😉 )

My second PN of the evening was M97 (NGC3587)- many of us will have observed this visually- surely there's nothing much new here? A bit of googling shows that all is not what it seems with the Owl- now the prototype for a new class of strigiform (owl like) planetary nebulae characterised by multipolar cavities in highly evolved planetary nebulae (https://academic.oup.com/mnras/article/479/3/3909/5037934?login=false ). I suspect many of us assumed that the owl eyes where the result of bipolar dynamics presented at a slightly oblique angle as seen in many "dumbell" style planetary nebula. But apparently that's not the case in M97. The dynamic modelling suggests a multipolar structure is required to create this visual appearance that includes both the "eyes" and some more complex structures at the periphery of the inner shell. The good news- there are other PN's that share similar features- Abell 33 and Abell 50 (although this might be a bit tricky due see any details because of it's small apparent diameter) and for the more southerly observers PN K 1-22 (ESO 378-1).  Give them a shot on your next clear night- I'm sure it'll be a hoot.

 

[Cosmic Geoff]

Here is an image of NGC3242, taken with my CPC800 and f6.3 focal reducer, processed in GIMP.  Camera is ASI224MC. The sky was hazy.

Edited April 2, 2022 by Cosmic Geoff

[Mike JW]

Hi Geoff, that has worked well.

Mike

[Cosmic Geoff]

Here is an image of the M97 Owl Nebula.  Taken with 102mm f5 achro, ASI224MC camera, live stacked, 10 frames x 30 sec, processed in GIMP.  Bortle 6 skies.

Edited April 3, 2022 by Cosmic Geoff

[Cosmic Geoff]

Two elusive planetary nebulae in Sagittarius: I tried to image these with my CPC800, but it was a total fail.  I tried again last night with my 102mm achro, ASI224MC camera, EQ5 Synscan + platesolve and resync.   For some reason the NGC6537 field refused to platesolve but the target was in field anyway.   The starfield around NGC6567 is exceptionally rich.  I had to look at online images today to pick out the planetary nebulae.  Both were low down in a hazy sky.