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Littleguy80

Flame Test

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I recently posted some observations on the Flame nebula in Orion. My report described a failed attempt to see the Flame using an OIII filter then success with an H-Beta filter later on. The main difference was a larger exit pupil when using the H-Beta. The Flame nebula is a reflection nebula and should therefore be more prominent without a filter, as a generalisation. My observations gained some attention as they didn't seem to corrolate with expected results. Last night, I carried out some testing to see which filter/eyepiece combination would deliver the best results.

The tests were carried out at my local dark site at Seething, home of the Norwich Astronomical Society. Testing took place over 40 minutes starting about 11:30pm. The test of each combination below was fairly short as I didn't want sky position to skew the results. Orion was rising so the the later tests in theory had better conditions.

The Eyepieces

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Explore Scientific 82 30mm. Exit pupil of 6.35mm in my 10" dob.

APM HDC 20mm. Exit pupil of 4.23mm in my 10" dob.

APM HDC 13mm. Exit pupil of 2.75mm in my 10" dob.

The Filters

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Baader Neodymium, Astronomik, UHC, Lumicon OIII and Astronomik H-Beta. 

Dark Adaption

Before testing, I observed Comet 46P/Wirtanen, NGC1 (Galaxy in Pegasus), NGC1300 (Galaxy in Eridanus) and California Nebula (in Perseus). The California Nebula was close to the prominence seen on Friday when I made my original observations.

Test 1 - No Filter

Both the 30mm ES82 and the 20mm APM gave clear views of the Flame with direct vision. The 13mm APM also gave clear views but seemed to suffer a bit with glare from Alnitak. 

Test 2 - Baader Neodymium

The Flame was visible but noticeably fainter with all 3 eyepieces. Both APM eyepieces seem to suffer with glare from Alnitak when using the Neodymium filter.

Test 3 - Astronomik UHC

Both the 30mm ES82 and 20mm APM gave improved views with the UHC filter compared to the Neodymium but fainter than no filter. Nothing was seen with the 13mm APM.

Test 4 - Lumicon OIII

With the 30mm ES82, the flame was faintly seen, on the edge of requiring averted vision. The 20mm APM required adverted vision and the 13mm showed nothing.

Test 5 - Astronomik H-Beta

The 30mm ES82 showed the Flame with direct vision and noticeably brighter than the OIII. The 20mm APM showed it much more faintly, again being on the line between requiring averted vision to observe. The 13mm again showed nothing.

Below are the notes I made during observations. I was wearing two pairs of gloves so please excuse my handwriting!

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Conclusions

The 20mm APM with no filter gave the best results though the 30mm ES82, also no filter, was a close second. Sky conditions weren't quite as good as Friday night when the original observations were made. You'll notice some moisture on the eyepieces in the picture above. Friday night all my equipment was completely dry at the end of the session. The OIII underperformed compared to what would be expected. I have found that the Lumicon OIII gives a darker image than the Astronomik OIII when observing objects such as the Veil. Had I used the Astronomik OIII then perhaps this would be closer to the expected results. Based on my results, I'd suggest keeping the exit pupil above 4mm, whether or not you choose to use a filter. For those wondering, unlike Friday night, I didn't see the Horsehead last night. I did feel little flat driving home last night after the excitement of seeing the Horsehead on Friday but then it wouldn't mean as much if you could see it every time you tried!

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Neil that is a very interesting review of several different filters and EPs.  I must admit that I never liked my Lumicon O-III filter, as much, when I compared it to my Astronomik O-III. I always found it a little too dark. My Lumicon filter came from the original Livermore factory in the United States.

I don't believe I have ever used my H.Beta filter on the Flame mainly because I thought it was a Reflection Nebula and therefore should be viewed with no filter - I must give this a go sometime.

Your report does show that your observing site must be pretty good - so well done again on a brilliant review.

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5 minutes ago, Mark at Beaufort said:

Neil that is a very interesting review of several different filters and EPs.  I must admit that I never liked my Lumicon O-III filter, as much, when I compared it to my Astronomik O-III. I always found it a little too dark. My Lumicon filter came from the original Livermore factory in the United States.

I don't believe I have ever used my H.Beta filter on the Flame mainly because I thought it was a Reflection Nebula and therefore should be viewed with no filter - I must give this a go sometime.

Your report does show that your observing site must be pretty good - so well done again on a brilliant review.

Thank you, Mark! The discovery of the Flame with the H-Beta was purely by accident by definitely an interesting result. 

The Lumicon OIII is quite an interesting filter. It’s definitely darker than the Astronomik OIII but I do find it can draw out the fainter nebulosity better. When I look at the main Eastern and Western Veil, the Astronomik OIII gives a great bright image. If I go for Pickering’s Triangle then it’s more prominent with the Lumicon. I intended to sell the Astronomik when I got the Lumicon but now I’m leaning towards keeping them both. 

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It is interesting that The Flame Nebula is referred to, colour coded in Interstellarum Deep Sky Atlas, as a Reflection Nebula. Close by is NGC 2023, which is a bluish reflection nebula, the Flame NGC 2024 is an emission nebula, perhaps with an element of reflection nebula properties.

A broad analysis

The Flame nebula is integral to the Orion Molecular Cloud Complex, which consists of Lambda Orionis, Barnard's Loop, M42 Orion Nebula and M43. Emission nebula are HIII, stellar forming regions, the hydrogen gas is ionised by ultra violet radiation by hot closely associated stars. The star formation of a very young open cluster is contained within the central of region of the Flame. The supergiant Alnitak is illuminating the gases of the Flame Nebula.

Reflection Nebula are dust particles reflected by starlight producing within images a bluish glow. Within the Orion Complex, there are M78, NGC 2071, NGC 2023, the Running Man Nebula NGC 1977 and the extremely faint IC 2118 Witch Head Nebula (considered to be illuminated by supergiant Rigel) among others.    

I have encountered quite easily M78 and NGC 2071 with my H-beta filter and low power eyepiece, positioning for an attempt to determine the, considered brighter section, northern portion of Barnard's Loop, by drifting along to open cluster NGC 2112. In pursuit of reflection nebula, as often mentioned no filter is considered applicable, yet all nebulae structures by their compositional complexity are worth experimenting with and without varied filter types and eyepiece focal length / exit pupil variations.       

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Excellent info, Iain. On Sunday night, following my testing on the Flame, I had a go at Barnard’s loop. Starting at M78 and NGC 2071 and moving across in the direction of the loop. I thought I could a detect a slight contrast change when moving across but when static I struggled to see it. The best I could say was maybe! M78 and NGC 2071 were both visible through the H-Beta filter. 

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Maybe is a good initial assessment Neil. Should you gain further opportunities then you ought be able to verify this observation. Drifting along between M78 and NGC 2112, there is no discernible structure or features, a very fine grey veil or curtain diminishing any background stars implies that you are located visually tracking across this selective portion of nebulosity. That's how I found it, approaching it repeatedly, a fine grey veil gained in certainty. We each know that the NV guys report on amazing and decisive observations, however that is not to underestimate the ability of our own eyes and optical glass to extract considerable subtleties even in some instances that perhaps NV assisted cannot resolve.

Barnard's Loop is a feature that I wish to return to this Winter, though so far not having any opportunity to do so. My approach though is to use a wide field refractor at a dark and remote wild camp site, a bit of a dream scenario should it come to fruition. Anyhow look forward to your further reports Neil and yes perhaps next time, who knows, you could with some certainty highlight Brainard's Loop as well in your account.    

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Great thread chaps. Most of this stuff is a pipe dream for me with our skies here, unless we get a chance at Bignor, although I'm not sure the skies there are good enough. It is still very interesting to read about the results and experiences, so thank you for that.

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With further regard to Reflection Nebula, The Merope and other associated nebula within M45, The Pleiades, is established for its potentially fine visual engagement. Much less known is the 'mini-Merope', or Barnard's Merope Nebula IC 349 a small and bright reflection knot just below Merope. Very difficult to see due to the glare of Merope and requires high power and aperture to stand a chance. Never attempted this myself, would make a fine challenge for anyone determined enough. Search for Bob King's article in Sky & Telescope - The Merope Nebula and its Well Kept Secret, concerning more information on this.

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19 minutes ago, scarp15 said:

With further regard to Reflection Nebula, The Merope and other associated nebula within M45, The Pleiades, is established for its potentially fine visual engagement. Much less known is the 'mini-Merope', or Barnard's Merope Nebula IC 349 a small and bright reflection knot just below Merope. Very difficult to see due to the glare of Merope and requires high power and aperture to stand a chance. Never attempted this myself, would make a fine challenge for anyone determined enough. Search for Bob King's article in Sky & Telescope - The Merope Nebula and its Well Kept Secret, concerning more information on this.

Thanks Iain. That’s a new one for me. I still feel like a have some work to do on the Merope Nebula. I have a good start but I think with more practise there’s more to be seen. 

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On 11/12/2018 at 05:42, scarp15 said:

It is interesting that The Flame Nebula is referred to, colour coded in Interstellarum Deep Sky Atlas, as a Reflection Nebula. Close by is NGC 2023, which is a bluish reflection nebula, the Flame NGC 2024 is an emission nebula, perhaps with an element of reflection nebula properties.

A broad analysis

The Flame nebula is integral to the Orion Molecular Cloud Complex, which consists of Lambda Orionis, Barnard's Loop, M42 Orion Nebula and M43. Emission nebula are HIII, stellar forming regions, the hydrogen gas is ionised by ultra violet radiation by hot closely associated stars. The star formation of a very young open cluster is contained within the central of region of the Flame. The supergiant Alnitak is illuminating the gases of the Flame Nebula.

Reflection Nebula are dust particles reflected by starlight producing within images a bluish glow. Within the Orion Complex, there are M78, NGC 2071, NGC 2023, the Running Man Nebula NGC 1977 and the extremely faint IC 2118 Witch Head Nebula (considered to be illuminated by supergiant Rigel) among others.    

I have encountered quite easily M78 and NGC 2071 with my H-beta filter and low power eyepiece, positioning for an attempt to determine the, considered brighter section, northern portion of Barnard's Loop, by drifting along to open cluster NGC 2112. In pursuit of reflection nebula, as often mentioned no filter is considered applicable, yet all nebulae structures by their compositional complexity are worth experimenting with and without varied filter types and eyepiece focal length / exit pupil variations.       

Excellent Iain.

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On 10/12/2018 at 15:45, Littleguy80 said:

My observations gained some attention as they didn't seem to corrolate with expected results

Great report and I have seen a filter work, not optimum but work on the Flame nebula. I think what  happens is that the Hb filter reduces glare or scatter from Alnitak seen in the eyepiece and the Hb lets just enough through to see it.

A technique I fall back on is the use of a narrow FOV eyepieces with widish field scopes on the Flame- like the other night with the 90mm frac. One of the reasons for such great success I have with the 15" f4.8 dob is the narrow FOV the focal length gives with superb hyperwides. Even then I can go with the 84deg Docter 12.5mm UWA narrowing up more and this eyepiece series gives such good contrast. It is not needed however as my 18mm ES 82, 18mm BCO etc show it very well too.

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Great observation and notes on filters Neil. Because of Alnitak the flame is a challenging object. I saw the flame only once through my Tak FS128 using a H-beta filter and from a dark out of town site. Then a year or two back I observed is from my garden observatory using my FC100DC and no filter, but I was very well dark adapted. On that night using the 100mm fluorite, I also picked out IC434 unfiltered, and a dark notch which I took to be the position of the Horse Head, though it didn't look much like a horse's head. The smallest aperture I've ever hear of being used for successfully seeing IC434, but not the Horse Head, was a 2.4" refractor used by Larry Krumenaker from New Jersey. He must have had excellent skies!

I feel sure I remember in Walter Scott Houston's Deep Sky Wonders articles from my old Sky & Telescope issues, mentioning the H-Beta filter as being the Horse Head Filter. The book below is worth having if you ever get the chance to grab a copy!

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Posted (edited)
On 07/01/2019 at 14:03, mikeDnight said:

I also picked out IC434 unfiltered, and a dark notch which I took to be the position of the Horse Head, though it didn't look much like a horse's head.

Thanks Mike. That’s some good going with relatively small aperture. I thought my Horsehead sighting with my 10” dob was at the bottom end of required aperture, apparently I wasn’t even close! I attributed my success on that night to quality of the sky. I was using low power to get the maximum exit pupil for the H-Beta filter. I thought the Horsehead looked like a little black sock puppet against IC434. I’d start at Alnitak where I could see the Flame and slowly move up and when I hit right point the black notch of the Horsehead would appear with averted vision. I had really low expectations of being able to see it so it was a bit of a shock when it appeared.

Thank you for the book suggestion. I’ll try and hunt down a copy of that :) 

Edited by Littleguy80
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30 minutes ago, Littleguy80 said:

Thanks Mike. That’s some good going with relatively small aperture. I thought my Horsehead sighting with my 10” dob was at the bottom end of required aperture, apparently I wasn’t even close! I attributed my success on that night to quality of the sky. I was using low power to get the maximum exit pupil for the H-Beta filter. I thought the Horsehead looked like a little black sock puppet against IC434. I’d start at Altinak where I could see the Flame and slowly move up and when I hit right point the black notch of the Horsehead would appear with averted vision. I had really low expectations of being able to see it so it was a bit of a shock when it appeared.

Thank you for the book suggestion. I’ll try and hunt down a copy of that :) 

I love the idea of the horse head nebula being called the Sock Puppet Nebula. Perhaps we should get together and rename every dso visible in amateur telescopes. I'm sure we'd come up with some hilarious titles. 

From now on though, it will always be the Sock Puppet Nebula to me! :icon_biggrin:

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On ‎07‎/‎01‎/‎2019 at 14:03, mikeDnight said:

 On that night using the 100mm fluorite, I also picked out IC434 unfiltered, and a dark notch which I took to be the position of the Horse Head, though it didn't look much like a horse's head. The smallest aperture I've ever hear of being used for successfully seeing IC434, but not the Horse Head, was a 2.4" refractor used by Larry Krumenaker from New Jersey. He must have had excellent skies!

 

That is quite astonishing Mike, my own encounter with IC434 /  B33 has been in NELM 6.33 skies (SQM-L: 21.4 mag) with a 14" dob, H-beta filter and employing averted vision (Orion being quite high in the South).  Do you have any further clarifying details to include for this? 

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