Big Dobs M33 Triangulum Challenge. Ethos21 vs Night Vision

[alanjgreen]

Date: Friday 30th November 2018. 1930-2200hrs
Scope: 20” f3.6 Lukehurst Dob with Paracorr (fl = 2089mm & f4.1).
Eyepieces: Ethos 21mm (x100), Ethos 13mm (x150).
Night Vision: Plossl 55mm (f2 x38), Panoptic 27mm (f4 x77) attached to PVS-14 with Photonis 4g INTENS.

 

After five months of concentrating on nebula (Sharpless objects mainly), the time had come to return to my first love – Galaxies.

I have been waiting patiently for M33 to make its way into a prime spot over my observing shed and for the moon to go away. Finally the opportunity arrived after what seems like two weeks of clouds & rain!

I took two sets of eyepieces down to the shed

1. My Ethos case for conventional viewing...
2. My NV (Night Vision) case with longer focal lengths to attach to my PVS-14 NV device...

With the help of my Nexus, I soon had M33 centred and let the battle commence!

 

Ethos13.

First up was the Ethos13. Wow, the galaxy was much larger than the 100 degree fov allowed by the E13. I could see a large “S” shape clearly with no averted needed. I settled in and started to look for other arms or some of the many “patches” of bright nebula within the galaxy. As arms and nebula hot spots were seen, I moved to sketch them on paper. After a few trips, it was obvious that I was just “in too close” and needed to step back with the lower magnification of the Ethos21.

 

Ethos21.

In with the Ethos21 and peer in. Wow that’s better. The galaxy scale was sufficiently reduced to enable me to see the whole thing. M33 was dominating most of the 100 degree fov and nudging was still required to get around to focus on each section of the galaxy. The main arms were there and also decent snippets of the other arms. I could see several “hot patches” and once again I started to make a sketch of the view.

 

Plossl 55mm & PVS-14.

Now it was time to see what the PVS-14 and 55mm Plossl could do. (I have had my night vision since the end of April and learned on M101 that the key to seeing arms with NV is to get the focal ratio as fast as possible, this is achieved with the 55mm Plossl which acts as a x0.5 reducer).

I played with the manual gain setting while looking at the main arms to find the position where the arms were showing at their best (too much gain overpowers the view so it needs to be less than the max). Once I was happy, I started to look and sketch the view. What was immediately noticeable was how the arm that runs out to NGC604 was much less visible that with the Ethos. The arm at the other side was much more visible and the several bright Ha patches shimmered on the face of the galaxy. There were fewer snippets of other arms but several Ha hot spots stood out clearly.

[The dashed line shows an “assumed” arm rather than a “seen” arm. I got the impression that the arms were there but it contradicts the glass view]

 

Conclusions.

Welcome back to the mighty Ethos21! It provided the most enjoyable view and enabled me to get up close and personal with M33 in a way that the Plossl55 and Night Vision had not. The experience of seemingly hovering just over the surface of these large galaxies is just amazing and makes my day everytime! The amount of spiral arms on offer to the observer who is willing to spend time at the eyepiece is astonishing. Its hard to beat M33 and M101

 

Supplemental.

I found that I had really missed the E21 and headed on afterwards to the Pleiades to see more of what I had been missing . The Pleiades and the Ethos21 are made for each other, the view was stunning with great views of the nebulosity surrounding the bright stars on offer. After not using the E21 for nearly six months, I can only conclude that the Ethos21 is one hell of an eyepiece and I need to remember that

 

Clear Skies,

Alan

[Mark at Beaufort]

Alan another great report. Like you I have been waiting for M33 to be in a prime position. Not sure whether you have seen this article but a useful reference when viewing M33 - https://www.skyandtelescope.com/observing/triple-treasure-in-triangulums-pinwheel110320150311/?et_mid=796780&rid=249217521

[alanjgreen]

6 minutes ago, Mark at Beaufort said:

Alan another great report. Like you I have been waiting for M33 to be in a prime position. Not sure whether you have seen this article but a useful reference when viewing M33 - https://www.skyandtelescope.com/observing/triple-treasure-in-triangulums-pinwheel110320150311/?et_mid=796780&rid=249217521

Thanks, I use this image to identify the patches

http://www.seetheglory.com/star-clusters-and-nebulae-in-the-triangulum-galaxy-m33/

[Stu]

Nice report Alan, good to hear that the big dob and a great eyepiece is still up to the mark after all that NV.

One question (genuine!) what do mean by assumed arm? Was it just a faint something with averted vision, or where you know the arm should be? As said, genuinely am interested.

Stu

[GavStar]

I like the diagrams Alan! ?

A key disadvantage of night Vision is that higher magnifications don’t work very well due to the higher resulting f ratio. So the 21mm Ethos has the significant benefit of around 100x mag vs the 55mm NV plossl of 38x. When trying to extract detail on galaxies I think this has a major impact. (As well as galaxies being more broadband rather than focussed on the red spectrum unlike nebulae - NV works fantastically well in the red but not the blue bit of the spectrum - hence NV is no good on reflection nebulae)

But from LP sites I find NV works really well on the larger galaxies such as m31, m81 and m82. At dark sites not so much benefit...

I’m really looking forward to seeing what my new 16 inch dob will show with normal glass (Ethos 21mm) on the Isle of Wight, particularly galaxies...

[bish]

Very nice report.  Have to say I am more than a little jealous! I've heard that filters help with M33, but I guess you don't have to bother when using NV.

[alanjgreen]

47 minutes ago, bish said:

Very nice report.  Have to say I am more than a little jealous! I've heard that filters help with M33, but I guess you don't have to bother when using NV.

I have previously tried with a UHC on M33 but the results were inconclusive, I would not say it did not help, the view was different, if you own the filter then silly not to give it a go!

Nothing beats a big mirror and a dark sky for M33. I already knew from last year that the E21 would be great on M33 when paired with the 20”. What I did not know is how NV would fair? It has proved better at smaller face ons where the stars are more condensed meaning the arms stand out better in Ha. As M33 is so big then the stars are more spread out and the red is less intense. 

M100 is an example of a face on where NV wins, I was able to see the whole arm structure with NV but not with glass.

M51 was also great with NV revealing black dust lanes running within each of the arms, that glass could not see.

I think the same M33 test re-run with the Borg107 may yield a win for the NV as with the smaller scopes, NV can get more mileage from the limited light on offer to the eyepiece. I have tried it with NV already and I was able to see the whole galaxy patch but the whole “S” of the arms was not clear, just the upper section. I have not tried glass with the Borg yet as I am still focused on my Sharpless challenge..

The most disappointing galaxies with NV are the tiny grey smudges which all appear identical as just a core whereas with glass you generally get some extension and shape.

However, nothing compares to seeing Markarians chain with the 100 degree ethos21 and a 20” mirror, this is the ultimate galaxy experience IMHO. It’s jaw dropping to just keep tripping over galaxy after galaxy after galaxy. There are just so many in Leo!

Alan

[Telescope40]

Very nice read,Alan. 

Sounds like a dream set up either way you go - NV or Ethos. 

Love the “supplemental” section. 

Reminds me of one Mr J T Kirk!! 

Regards. John 

[bish]

6 hours ago, alanjgreen said:

I have previously tried with a UHC on M33 but the results were inconclusive, I would not say it did not help, the view was different, if you own the filter then silly not to give it a go!

Nothing beats a big mirror and a dark sky for M33. I already knew from last year that the E21 would be great on M33 when paired with the 20”. What I did not know is how NV would fair? It has proved better at smaller face ons where the stars are more condensed meaning the arms stand out better in Ha. As M33 is so big then the stars are more spread out and the red is less intense. 

M100 is an example of a face on where NV wins, I was able to see the whole arm structure with NV but not with glass.

M51 was also great with NV revealing black dust lanes running within each of the arms, that glass could not see.

I think the same M33 test re-run with the Borg107 may yield a win for the NV as with the smaller scopes, NV can get more mileage from the limited light on offer to the eyepiece. I have tried it with NV already and I was able to see the whole galaxy patch but the whole “S” of the arms was not clear, just the upper section. I have not tried glass with the Borg yet as I am still focused on my Sharpless challenge..

The most disappointing galaxies with NV are the tiny grey smudges which all appear identical as just a core whereas with glass you generally get some extension and shape.

However, nothing compares to seeing Markarians chain with the 100 degree ethos21 and a 20” mirror, this is the ultimate galaxy experience IMHO. It’s jaw dropping to just keep tripping over galaxy after galaxy after galaxy. There are just so many in Leo!

Alan

That's very interesting Alan. I assumed that NV would always win out. I haven't tried a filter on M33 with my scope. Years ago a had a look with somebody elses set up with a UHC but didn't get to compare without it.

Markarians chain with a 20", E21 and dark sky would keep me smiling all night. I agree that multiple galaxies in the same fov is probably the most amazing sight in astronomy. The Hubble deep field image is awe inspiring and probably my favourite image

 

 

[Littleguy80]

Excellent report, Alan. Your reports from last season picking out NGCs in M33 with the big dob were some of my favourites. The use of night vision almost gives you a composite view with the Ha regions being better in MV and the arms with the Ethos. 

[Littleguy80]

19 hours ago, GavStar said:

When trying to extract detail on galaxies I think this has a major impact. (As well as galaxies being more broadband rather than focussed on the red spectrum unlike nebulae - NV works fantastically well in the red but not the blue bit of the spectrum - hence NV is no good on reflection nebulae)

 

Makes me wonder if something along the lines of NV exists or could be developed that would give a similar effect in the blue end of the spectrum. It would be fascinating to see which objects would stand out then. 

[Olli]

Great report Alan,Surprised you had the chance to get out. Weather has been rubbish for the past two or so months!

[Eastman]

On ‎01‎/‎12‎/‎2018 at 10:39, alanjgreen said:

The amount of spiral arms on offer to the observer who is willing to spend time at the eyepiece is astonishing. Its hard to beat M33 and M101

Great report Alan, wow spiral arms. M33 I find very hard to see at all,