29 Jan - Big Dob enjoys Orion's nebulas and reveals a surprise in M37/M35 (Night Vision)

[alanjgreen]

Date: Tuesday 29th Jan 2019. 2015-2315hrs
Scope: 20” f3.6 Lukehurst Dob with Paracorr (fl = 2089mm & f4.1).
Night Vision: PVS-14 with Photonis 4g INTENS.
Eyepieces: Plossl 55mm (f2 x38), Panoptic 35mm (f3 x60).
Filters: Chroma 5nm Ha filter.
Moon: 0%

 

Make Hay While The Sun Shines.

The Weather forecast changed and was now showing as two clear cold nights coming my way. I have had a couple of sessions already but we all know that you must “make hay while the moon is away” in this game!

My plan was to hit Orion hard and make up for the disappointment of the windy night last Sunday which kept me inside until Orion had passed the drop-down side of the shed.

Tonight I also planned to bring the Panoptic 35mm into play for a little more magnification (x60) on my chosen Ha nebula targets.

 

An Initial Run with the 55mm Plossl.

I had myself setup (in the shed) and aligned (Nexus 2-star) by 2015hrs and loaded the Chroma 5nm Ha CCD filter onto the Paracorr2. Then inserted the 55mm Plossl and attached the PVS-14 Night Vision Device to it using the TNVC a-focal astronomy adapter.

Flaming Star – First up was the Flaming star. It provided a decent view with some wispy fine detail including the two right angles of the back corner and multiple bright fuzzy lines at varying angles within). The 3D view of “my best outing” was not repeated on this occasion so I determined that the sky was not “at its best”.

IC410/417 – I nudged over to IC410 which was looking good with three black holes on one side and another large black hole on the other side. The nebula was more lush than the Flaming star and I enjoyed the view. Over to IC417 where the “spider” was visible but again not “at its best”.

M1 Crab – I headed down to the Crab and was rewarded by 5 nice ovals shapes interlinked in a bubble like structure. It took time and averted to tease out the outer bubbles whereas the central bubbles were much easier.

NGC2174 Monkeys Head – Over to the Monkeys Head and I was greeted with a very bright and “in your face” view of a neanderthal man. The edges of the facial features showed several bright areas. There was a tiny nebula spot set away from the mouth and a bright spot around the “ear”. The larger right patch to the neck (that I have seen previously) was there but took some averted to see it.

Sh2-269 – small bright “angels wings” shape.
Sh2-267 – medium sized faintish patch.
Sh2-268 – Faint and large. Like an upside-down pear drop. I could see black detailing inside around a line of bright stars.

Sh2-270 – FAIL. I am missing this Sharpless object and I failed to find it once again! I found a “candidate” but internet research this morning says that it was not it. I have compared sky safari location to an image and it seems they are slightly out so I have added a marked into sky safari ready for my next attempt. This object is only 1’ x 1’ size so maybe I need more magnification?

HorseHead IC434 – Up to IC434 and Wow it’s really wide and bright.  I nudged above Alnitak and there was a lovely shapely horse head. The head showed the snout and neck but I was also attracted to the bright white line that was running through IC434 as it was really standing out. As I nudged around, it really was amazing to see just how long and wide IC434 actually is. The whole of this region is just full of a faint nebulosity glow.

Flame – I nudged down to the Flame and at last it was a view to savour. My last couple of visits have been underwhelming but tonight it was standing out bold as brass. I could make out many wispy black details to the RHS and see the small black circle to the LHS. It really was nice but I had to go back to the horsey as it was probably “beating it” for loveliness tonight!

M42 – Fantastic. I swore out loud as M42 swung into view. God its bright and God its lovely. The swirling, looping nebula behind the fish head is overwhelming. The ray of black hydrogen spewing out of the mouth of the fish head is like an “oil leak”. There is so much to see that I settle in on my chair and let it float across my fov several times as I try to tease out a detail that I have not noticed before. Tonight I settled on a couple of black areas to the LHS lower of the fish head. I even though that I could see the Candle Star sitting in the fishes mouth. I could see all 4 trapezium stars clearly so maybe the transparency was improving…

Running Man NGC1975 – Time to get into Orion and start with my on-going challenge to see the Running Man. I am gradually building up more mental notes to help with seeing this difficult target. I could easily see a very bright patch sitting over three stars below M43. I could see a black finger coming down the LHS of the 3 stars. I got distracted by further nebulosity down underneath an open cluster below and became confused as to where the black legs of the running man actually are?

Sh2-278 – Triangular kite shaped nebula but faint and time needed to get to grips with it.

 

Time to Increase the Magnification with the 35mm Panoptic.

The image presented by the 55mm Plossl (when used with Night Vision and a fast focal ratio scope) leaves a lot to be desired especially around the edges of the fov. The 35mm Panoptic does not suffer from these issues and provides a sharp edge-to-edge view. However, the 35mm only acts as a 0.7x reducer so some image brightness is lost compared to the 55mm Plossl. Therefore, you need to use more “gain” (a knob on the PVS-14) to compensate for the darker image. From my experience the 55mm Plossl seems to always win out because the brighter image just shows more stuff and I just ignore the outer edges of the FOV.

 

Flaming Star – Back to the Flaming star and I could see some nice texture and details within. The larger image scale meant more nudging was needed and I felt that I preferred the 55mm on this object.

IC410 – Very nice and the extra brightness of the nebula meant that nothing felt lost on this target. I felt the 35mm was the winner here.

M1 crab – A nice view. The bubbles were now a little larger but I felt that I was not seeing more than with the 55mm so I will call this one a tie.

Fox Fur/Cone – With the 35mm loaded, I wanted to see if I could get more from the Cone than the other night. I started at the central star cluster and nebulosity was showing all around except for near the bright stars which seemed to have cleared a nice black patch over them. I nudged up and right to the Cone. It was pretty obvious as it came into view and a decent size too. It felt like it was an inch long and both sides were clearly visible running to a sharp multi colored double at the point. (With NV I cannot see colors but I can see shades and it was noticeable that the double stars were not the same color). I played with the gain control trying to get more out of the cone with not much success. It’s a difficult target and although I could see it easily, if the same view had been presented to my wife then she would have said “where is it?”. I nudged left and right in long sweeps for a while as I tried to cover the area of the Fox Fur nebula (Huge) and see the many lanes of bright nebula within. There was plenty to see but I prefer the Fox Fur view in the Borg107 where I can more easily take it all in.

Rosette – Holy Cow, the highlight of the night! I would have to say this must have been my “best ever” view of the Rosette even allowing for the fact that I had to nudge around it thanks to the extra scale of the 35mm Panoptic. The Nebula was so lush and large. The extra magnification really allowed me to get deeper into the many intricate black lanes that run within the lower and left sides of this nebula. I found further black areas to investigate in the upper RHS. And I noticed three small nebula patches embedded within the centre star cluster (RHS) which I have not noticed previously.

Sh2-280 – Nudge down to a large nebula patch with two black eyes. The RHS edge was brighter and also below.
Sh2-282 – Nudge down to a triangular patch on its side. 4 stars were carving out a black area behind the tip.
Sh2-283 – A tiny bright patch (located at star HD291952 in Sky Safari).

IC434 – Over to view the horse head with more magnification and I was not disappointed. The Horse was there in all its glory – snout, neck and an ear. I let it drift across the view a few times. I also noticed that if I turn the “gain” down then the outer edges of the horse head took on a brighter glow? A win for the 35mm here.

Flame – Up to the Flame which was big and bright. I think that the 55mm Plossl view was slightly more feature-ridden and the loss of focal ratio had taken something away. It still looked great though, don’t get me wrong!

Running Man – Back to the nemesis that is “the Running Man” and unbelievably I was able to tease out some black edge detail. I could see a vertical piece LHS and a longer horizontal piece under the three stars (more RHS). The black lane seemed to reach up and touch the middle of the three stars too. Another win for the 35mm.

M42 – You have to don’t you? A great view but with diminished resolution compared to the 55mm Plossl IMHO.

Medusa – An easy black crescent. It had a very bright tip at the bottom and also a less bright tip at the top. The Crescent sides seemed incomplete and I chalked this as another win for the 55mm.

Sh2-241 – A small bright patch with a central star and a black area within.
Sh2-242 – A mid-size patch with an off-centre bright star within.

 

What Happens when you View an Open Cluster with a 5nm Ha Filter?

By now I was getting cold and Orion was passed the drop down side of my shed. I headed up towards the zenith and decided to view M37 with the 5nm Ha CCD filter still loaded on the Paracorr2.

 

M37 – A lovely bright open cluster fills the fov of the 35mm Panoptic. As I turn the gain down on the NVD something interesting happens… A black lane structure appears running in some of the gaps between the stars of the cluster. It takes on an appearance more reminiscent of Caroline’s Rose with conventional eyepieces. I continue to play with the gain. It seems some stars are within nebula lanes/patches and some stars are within or next to these black (Hydrogen) lanes. I stood there pondering whether the stars were clearing the nebula to reveal the blackness or the blackness was somehow connecting lines of stars within the cluster?

M35 – Onto another nearby cluster M35. Once again, the same thing. With the gain down then black snaking lanes appear within the cluster. But there are lanes/patches of nebulosity too (or is it reflecting dust?)

 

IC443/444 – I finished with a short hop over to one of my favourite objects, the Jelly fish, IC443. Wow, the detail showing within the pancake of the Jellyfish was great. The flat head had two clear sides and dimmer/blacker areas within. There were some shimmering brighter bits too. The outer edges had clear definition as it steps down and curves away. I could see a single thread heading away from the pancake head towards IC444 and followed it away from IC443. I eventually ran into four thick parallel lanes of nebula near the strangely named “Tejat Posterior” star. I went back to IC443 and followed the tentacles running away to the left this time.

 

Thoughts of the observer.

• It was nice to get some use from the Pan35 at last. I seem to robotically load up the 55mm Plossl these days. I did prove on several targets that the extra magnification of the 35mm Plossl cannot compensate for the loss of focal ratio provided by the 55mm Plossl. BUT I did also see some benefit on several targets notably the Rosette, Horse Head & Running Man. Looks like I need to use both.
• The dark lanes in the open clusters M37 & M35 were an unexpected bonus and I think I will be trying the 5nm Ha filter on other non-nebula targets (M45 & M13 for instance) in the near future. I have looked on the internet for some Ha images of the open clusters but nothing was immediately found that showed what I was seeing? Perhaps one of the NV phonetography guys can get a shot of this feature?
• Its forecast clear again tonight so I packed up early so I could get some sleep in preparation.

 

Hope you are getting some clear skies too?
Alan

[mikeDnight]

By gum Alan, that's a great session! You almost have me wanting a 20" Dob. That's very naughty!! 

[Peter Drew]

35 minutes ago, mikeDnight said:

By gum Alan, that's a great session! You almost have me wanting a 20" Dob. That's very naughty!! 

We've got one just "up the road" from you Mike. Not trying to tempt you or anything.  

[mikeDnight]

58 minutes ago, Peter Drew said:

We've got one just "up the road" from you Mike. Not trying to tempt you or anything.  

I might just take you up on that offer Peter. 

[oldfruit]

A great report. I always enjoy reading of your sessions with the big dob. Your reports are very descriptive and it almost feels like we are there with you. Thank you and keep them coming!

[Littleguy80]

Great report, Alan. Does night vision work better with a narrower FOV? I noticed it’s plossl and panoptic rather than Ethos or Nagler? Or is that simply a side effect of needing a long focal length EP?

[alanjgreen]

43 minutes ago, Littleguy80 said:

Great report, Alan. Does night vision work better with a narrower FOV? I noticed it’s plossl and panoptic rather than Ethos or Nagler? Or is that simply a side effect of needing a long focal length EP?

Thanks Neil.

The night vision device can only ever show you the centre 40 degrees of fov, it does not matter which type of Televue EP I use. I have used my device with the Ethos 13mm and it worked fine, you just get the centre 40 degrees, it’s a well corrected 40 degrees and of course if the better quality EP can pick up something extra then you will see that too. 

I find that below the 18.2mm focal length of the DeLite then the image gets too dark and shows less that you can see with “less magnification but brighter image” of the longer focal lengths.

The DeLite works well for supernova spotting where the extra magnification provided can reveal fainter stars. The view is sharp and well corrected. It’s pretty good on globular clusters too.

The Panoptics offer a sharper view than the Plossls with nicer stars around the outer fov. It’s a shame the 41mm Pan is so big! The 35mm is a nice size/weight compromise.

The 55mm plossl offers the brightest image although it’s a bit soft around the outer 10 degrees of the fov in my fast scopes. This fastest speed generally reveals more galaxy arms or nebula dust so you have to put up with the soft edges. The 55mm can feel a little washed out too so needs the gain turning down a bit to darken up the background. 

The main thing is that the view through any EP with night vision does not feel like the traditional 40 degree view ( ie. looking “down a straw”), the magnification is lower and therefore the tfov is wider and packed with stars etc to keep your eye busy.

I am still using the Ethos in the traditional way and it’s a wow every time you return to the 100 degrees, the “space walk” view especially of the large face on galaxies is something I never tire of and “in your face” when switching directly from the NVD. 

- Although I have now found that a walk through Leo at x38 with only 40 degrees gives the same “galaxies everywhere you look” experience as I can now see anything down to mag 16 with decent brightness directly!

The bottom line is that at least you can save on EP cost as you look to buy additional EPs/filters for use with a night vision device. 100 / 82 degree EPs could be sacrificed to raise funds for other purchases without fear of losing out.

- I found out that some early NVD were 60 degrees fov but they were huge and heavy so the military demanded smaller and lighter units be created.

I have to be honest and say that the 40 degree fov is pretty irrelevant to the NV experience. My wish list is for Televue to make an 80mm EP!! (or just redo the 55mm Plossl to work better with ParaCorr and faster scopes).

Alan

[Littleguy80]

Thanks Alan. Very interesting insight. I didn’t realise night vision was restricted to 40 degrees, although that doesn’t sound as limiting as one might expect. Having said that, I enjoy using my orthos and they’re only 40 degree of course.