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The Horsehead Nebula was easy in my ED80

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#1 _Z_

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Posted 10 February 2013 - 06:16 PM

Last night I met two friends near Point Lookout, MD, where the sky at zenith and to the south is fairly dark being next to the Chesapeake Bay. The storm that just blew through gave us some of the best transparency we've ever had and skies were around mag 6 to 6.25.

I could only bring my ED80 with me, but I set out trying to observe some of the hardest things I could. After seeing the Horsehead in my friend's 25" obsession about the easiest we've ever seen it (h-beta used), I tried it in my ED80. I thought I was looking at the Flame Nebula at first. When I took the filter off, that nebula significantly dimmed and the faint flame nebula was visible on the other side of alnitak. Putting the h-beta back on at 60x it was unreal how bright the background nebulosity (IC434) was, it was as bright as M42 would be without a filter! I put in the ES 4.7mm for 127x and thought I might be seeing the Horsehead in the nebula, but I couldn't get Alnitak out of the 82º FOV without B33 so far off to the side as well. I opted for an eyepiece with few fans, the Celestron 4mm kit plossl. The narrow FOV at 150x was just what I needed. Alnitak was gone and the nebula easily revealed the Horsehead and even a hint of the direction it was pointing. Switching back to the 4.7mm it was easier to see the horsehead. Both of the people I was with confirmed this and it wasn't even difficult for them, which I still can't believe.

Next up I tried to find the California nebula. My 40mm Meade SWA gave me a 4.5º TFOV at 15x and with the h-beta filter again it was dim but it was definitely visible and was a great view seeing it all at once like that.

I also tried for the Flaming Star Nebula later that night. I hadn't observed it before, and I thought I was seeing a faint glow around one star, but the whole area seemed to have a glow to an extent. This morning I checked the deep images and learned that the entire area is full of nebulosity, so it looks like the Flaming Star Nebula and then some was also observed in the ED80!

One of the guys had a CPC1100 and likes to go after every galaxy he can. Tonight he found NGC 2493, which is mag 12 and was easy to see in his scope. He asked me if I could see the companion, 2495, which is mag 15.2. It was really tough but I managed to catch a few glimpses of it. We put the 25" obsession on it and it was a lot easier to see it. When looking through the obsession I noticed something else was there though, and it turned out to be galaxy CGC207-017, which is magnitude 15.6. Now that we knew where all 3 were in the obsession, we went back and were able to see the 15.2 galaxy more easily and we even managed to see the mag 15.6 galaxy in the CPC1100. Considering the limiting magnitude of an 11" is 16, i'd say we pushed that scope pretty far!

Overall it was a very productive night and we really went deeper than expected with some incredible transparency.

#2 IVM

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Posted 10 February 2013 - 07:37 PM

Nice observation! I haven't seen it with this kind of aperture, but the magnification used makes sense to me and I am guessing this was the key.

#3 _Z_

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Posted 10 February 2013 - 07:55 PM

Right, the low power really made IC434 extremely bright so B33 was easy to pick out. When we observed the horsehead in the 25" obsession, probably in the 200-250x range, the whole nebula was visible, but a much dimmer haze.

#4 GlennLeDrew

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Posted 11 February 2013 - 12:37 AM

IC434 through a filter as bright as M42 without filter?!? I'll have some of what you're smoking! :grin:

#5 _Z_

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Posted 11 February 2013 - 08:57 AM

IC434 through a filter as bright as M42 without filter?!? I'll have some of what you're smoking! :grin:


I didn't believe it was IC434 either until I took the filter off and saw the flame was on the other side of Alnitak. An 80mm under dark skies can show some impressive things.

#6 leviathan

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Posted 11 February 2013 - 01:02 PM

Congrats ! IC 434 in 80ED is of course very difficult object. I think transparency and H-Beta filter helped you.

#7 GlennLeDrew

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Posted 11 February 2013 - 01:35 PM

A nebula does not brighten nebulosity; it darkens the sky, thereby increasing contrast.

Actually, a nebula is brighter *without* the filter, for two reasons:
1) The filter is not 100% efficient, and so dims the nebula by as much as about 10%.
2) The nebula is seen through sky glow, and so its brightness is increased by that glow superimposed upon it. In daytime, IC434 is a *bit* brighter than the daytime sky.

To say an object whose surface brightness is perhaps 25 MPSAS, when seen through a filter, appeared as bright as the unfiltered view of an object having a surface brightness some 10 magnitudes, or 10,000 times brighter, goes well beyond exaggeration.

The filter improved the contrast by about 2.6 magnitudes, or a factor of 11. If we assume your sky was as dark as could be, or 22 MPSAS, and IC434 is 25 MPSAS (which might be a tad generous), sans filter the nebula is 3 magnitudes darker than the sky. If the filter darkened the sky by 2.6 magnitudes, the nebula now appears to be 0.4 magnitudes fainter than the sky.

Much of M42 has a surface brightness above 18 MPSAS, with the Huygenian region peaking at 14. Under even a not so dark sky of 20 MPSAS, much of M42 is at least 2 magnitudes brighter than the sky. And under a 22 MPSAS sky the difference is at least 4 magnitudes.

Unfiltered M42 is like day to filtered IC 434's night. Not only in terms of raw brightness, but contrast too.

#8 David Knisely

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Posted 11 February 2013 - 02:06 PM

GlenLeDrew wrote:

To say an object whose surface brightness is perhaps 25 MPSAS, when seen through a filter, appeared as bright as the unfiltered view of an object having a surface brightness some 10 magnitudes, or 10,000 times brighter, goes well beyond exaggeration.


I have to agree. I have seen the faint background glow of IC 424 in an 80mm f/5 refractor using the H-Beta filter, but almost never without it, and even with the filter, the nebula never appeared very bright. At most, it appeared as a very slight brightening of the sky background. A friend of mine says he saw the Horsehead with that same scope, but I wonder if he was mistaking a section of the Flame for the Horsehead itself. The smallest scope I have personally seen the Horsehead in is my 100mm f/6 refractor, but even then, it was far from obvious, although I could definitely tell it was there (mostly because I knew exactly where it was to begin with). Again, the H-Beta filter was the real game-changer, as it made the difference between seeing the Horsehead for certain and just seeing hints of a very faint diffuse glow in the area with some question as to whether the dark nebula was there or not. Clear skies to you.

#9 kansas skies

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Posted 11 February 2013 - 02:36 PM

I've never used a filter with the the Horsehead, but it sounds like it worked very well for you. I do think I'd hang on to that ED80, as it sounds like you have an exceptional scope there. Congratulations on a real accomplishment.

Bill

#10 IVM

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Posted 11 February 2013 - 02:39 PM

I could not see B33 with my 4" and it seems that the mistake was not going to higher powers than 70x. (It is difficult to use higher powers with the ancient Televue mount it rides on.) Note that the OP did not see it at 60x but saw it at 150 and then 127x. And on extended nebulous objects 80 mm is essentially the same as 100 mm, because at 4/5 the magnification in the latter the former will show the same surface brightness.

As far as the possibly exaggerated comparison with M42, Glenn's numbers are as always illuminating, but we should remember that the eye is not a photometer. It is attuned to what is before it at the moment. If the meager contrast of IC 434 is all it sees (and nothing outside the eyepiece at a real dark site), then it may appear comparable to M42 - at least I imagine it might. I am reluctant to compare apparent brightnesses of nebulae not seen simultaneously in the eyepiece except most casually.

#11 Dave Mitsky

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Posted 11 February 2013 - 02:40 PM

I was at the best "local" dark site (a 90 minute drive) on Saturday night with three fellow CAS members. At one point, an SQM reading of 21.4 (a NELM of ~6.3) was attained.

One of the guys was using a 10" f/4.7 Orion SkyQuest XT10 Dob. He was viewing NGC 2024 and remarked at how good it looked. (Orion was just a bit past the meridian at the time.) I took a peek and then moved the scope to IC 434. I was able to discern a bit of nebulosity and suggested that we give B33 a try. He didn't happen to own an H-beta filter and didn't want to borrow one so we used his 1.25" Orion UltraBlock. I further suggested employing an ocular that produced an exit pupil of around 5mm. He attached the filter to a 25mm Plössl eyepiece and inserted it into the focuser. After a bit, I was able to make out the Horsehead as an indistinct, darker region. He sat down at the eyepiece and was also able to see it. Even with a filtered 10" Newtonian from a very good site it was not particularly easy.

Later on, we observed B33 through the two big Dobs that were present, a 22" f/3.6 SDM and a 25" f/4 Obsession. The Horsehead was not a difficult target through those scopes.

Dave Mitsky

#12 _Z_

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Posted 11 February 2013 - 03:28 PM

I could not see B33 with my 4" and it seems that the mistake was not going to higher powers than 70x. (It is difficult to use higher powers with the ancient Televue mount it rides on.) Note that the OP did not see it at 60x but saw it at 150 and then 127x. And on extended nebulous objects 80 mm is essentially the same as 100 mm, because at 4/5 the magnification in the latter the former will show the same surface brightness.

As far as the possibly exaggerated comparison with M42, Glenn's numbers are as always illuminating, but we should remember that the eye is not a photometer. It is attuned to what is before it at the moment. If the meager contrast of IC 434 is all it sees (and nothing outside the eyepiece at a real dark site), then it may appear comparable to M42 - at least I imagine it might. I am reluctant to compare apparent brightnesses of nebulae not seen simultaneously in the eyepiece except most casually.


Thanks. You're right, B33 was seen initially at 150x and then at 127x after finding where it was located.

IC434 filtered is not the same brightness as M42, it was not meant as a mathematical observation, more of a remark about how incredibly easy it was to pick out IC434, you couldn't miss it at 60x.

Every time I push the ED80 or other scopes of mine to insane limits, I have larger scopes around to start with. Observing these faint objects in a big 20-25" scope, seeing where whatever detail (B33, pillars of creation, etc) is in the nebula and then being able to go over to the 80mm and compare it right away makes it significantly easier to spot faint details.

That same principle is why we had a tough time spotting a mag 15.2 galaxy in the C11, but when we viewed it in the 25" obsession, I was able to spot the 15.2 and the 15.6. Going back to the C11, we knew where both were and were more easily able to spot the 15.2 and could also make out the 15.6 galaxy.

Trying to spot that 15.2 galaxy the first time took a lot of work, whereas B33 was an obvious gap in IC434 with enough magnification, hence why I considered it easy to see.

It probably helps being half of your guys' age too. :getem:

#13 IVM

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Posted 11 February 2013 - 04:09 PM

Seeing something through a large telescope first (and immediately before) is a great trick indeed.

#14 RolandosCY

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Posted 11 February 2013 - 09:09 PM

Guys... This is an extract from one old observing report I posted here on 11/20/2009:

Before calling it a night, I did check the area with my 80mm refractor. Amazingly, I did manage to spot IC434 first with the H-beta filter and then without it – with direct vision (no Horsehead, but maybe I did not try hard enough!). Unbelievable what excellent conditions can produce.

http://www.cloudynig...Board=deep&N...

The 80mm refractor mentioned was a SkyWatcher ED80Pro. On a side note, last Tuesday (a week ago) I did locate IC434 without a filter (but with averted vision) in an AT 152 f5.9 achromat. At the same time the Flame Nebula was bright and easy. I tried to locate it in my Tak FS102 which was set up nearby, but within minutes high altitude clouds moved in and we could not even see the Flame for the next couple of hours (even through holes in the clouds) when we finally gave up. The visibility of IC434 (and consequently of the HorseHead) depends greatly on transparency.

My own experience shows that IC434 can be seen in a good 3-inch refractor. And once IC434 is visible, then the HH should be doable as well...

#15 _Z_

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Posted 12 February 2013 - 08:12 AM

Guys... This is an extract from one old observing report I posted here on 11/20/2009:

Before calling it a night, I did check the area with my 80mm refractor. Amazingly, I did manage to spot IC434 first with the H-beta filter and then without it – with direct vision (no Horsehead, but maybe I did not try hard enough!). Unbelievable what excellent conditions can produce.

http://www.cloudynig...Board=deep&N...

The 80mm refractor mentioned was a SkyWatcher ED80Pro. On a side note, last Tuesday (a week ago) I did locate IC434 without a filter (but with averted vision) in an AT 152 f5.9 achromat. At the same time the Flame Nebula was bright and easy. I tried to locate it in my Tak FS102 which was set up nearby, but within minutes high altitude clouds moved in and we could not even see the Flame for the next couple of hours (even through holes in the clouds) when we finally gave up. The visibility of IC434 (and consequently of the HorseHead) depends greatly on transparency.

My own experience shows that IC434 can be seen in a good 3-inch refractor. And once IC434 is visible, then the HH should be doable as well...


Thanks Roland. :) It's amazing what can be seen in an 80mm, just takes being more than an armchair astronomer speculating over the results to find out.

The fact that my setting up and tearing down the whole setup takes minutes makes observing with that scope easy and lots of fun every time.

#16 Widespread

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Posted 12 February 2013 - 04:11 PM

I saw IC434 last night for the first time, a dim hazy liver-shaped patch near Alnitak. I tried to spot the horsie, but alas.

I was using a 90mm f/7 refractor with 24ES68.

Good job on a tough target!

Best,
David

#17 leviathan

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Posted 12 February 2013 - 04:17 PM

H-Beta ?

#18 David Knisely

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Posted 12 February 2013 - 05:38 PM

H-Beta ?


H-Beta refers to filters which pass only the bluish Hydrogen-Beta (H-Beta) emission line at 4861 angstroms. A proper narrow-band nebula filter like the Lumicon UHC, Orion Ultrablock, or DGM Optics NPB will also pass the H-Beta line, but on the Horsehead, the contrast of the object tends to be quite a bit higher when using the H-Beta filter. The very first time I got to clearly see the Horsehead was around 1980 or so, using a 10 inch f/5 Newtonian equipped with the "brand-new" (at the time) Lumicon UHC filter. After seeing that, I went over to my own 8 inch f/7 Newtonian and put the UHC in that scope. Sure enough, I could just see the Horsehead, although not as well as in that 10 inch. On most decent dark nights now, I can get at least a glimpse of the Horsehead in my scopes using just a narrow-band filter, although again, it is far easier using my H-Beta filter. I have also seen the Horsehead without a filter in my 10 inch Newtonian, but the nights when that is possible are quite rare, and even then, I generally prefer the filtered view. Indeed, one night from my magnitude 5.6 driveway, I caught the Horsehead in my 9.25 inch SCT at 59x using the Lumicon H-Beta filter. Without that filter, there was no trace of it or of the background IC 434 nebulosity. Clear skies to you.

#19 blb

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Posted 12 February 2013 - 06:44 PM

I saw IC434 last night for the first time, a dim hazy liver-shaped patch near Alnitak. I tried to spot the horsie, but alas.

Widespread, Are you sure you are looking at the correct nebula? The Flame Nebula, NGC 2024, looks more like a liver or a heart shaped fan east of Alnitak to me, but IC 434 looks like a line of nebulosity running south of Alnitak. If you take some time and continue looking at the Flame Nebula, maybe with some averted vision, you will see the dark nebula that gives this nebula it's name.

Zeldaboy, It is my experance that the darker and more transparent the sky is, the easier the nebula, IC 434, is to see. There have been a couple of really good nights in the last ten years that this nebula, IC 434 did appear much brighter than you normaly think when you think of it. I attribute this to a great night. Maybe that is what you experianced. Anyway, good catch.

#20 george golitzin

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Posted 12 February 2013 - 08:31 PM

H-Beta ?


H-Beta refers to filters which pass only the bluish Hydrogen-Beta (H-Beta) emission line at 4861 angstroms. A proper narrow-band nebula filter like the Lumicon UHC, Orion Ultrablock, or DGM Optics NPB will also pass the H-Beta line, but on the Horsehead, the contrast of the object tends to be quite a bit higher when using the H-Beta filter. The very first time I got to clearly see the Horsehead was around 1980 or so, using a 10 inch f/5 Newtonian equipped with the "brand-new" (at the time) Lumicon UHC filter. After seeing that, I went over to my own 8 inch f/7 Newtonian and put the UHC in that scope. Sure enough, I could just see the Horsehead, although not as well as in that 10 inch. On most decent dark nights now, I can get at least a glimpse of the Horsehead in my scopes using just a narrow-band filter, although again, it is far easier using my H-Beta filter. I have also seen the Horsehead without a filter in my 10 inch Newtonian, but the nights when that is possible are quite rare, and even then, I generally prefer the filtered view. Indeed, one night from my magnitude 5.6 driveway, I caught the Horsehead in my 9.25 inch SCT at 59x using the Lumicon H-Beta filter. Without that filter, there was no trace of it or of the background IC 434 nebulosity. Clear skies to you.



David, I think Leviathan was asking the OP if he used an h-beta filter.

-g

#21 _Z_

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Posted 12 February 2013 - 08:34 PM

I saw IC434 last night for the first time, a dim hazy liver-shaped patch near Alnitak. I tried to spot the horsie, but alas.

I was using a 90mm f/7 refractor with 24ES68.

Good job on a tough target!

Best,
David


Congrats on IC434! To get the horsehead you'll want more than that 24mm, and a narrower FOV helps too. Get Alnitak out of the FOV and pump that mag up to 100-150x and the horsehead can be easier to see. Then backing the magnification back down you will recognize where the horsehead is at and will be able to pick it out much easier.

#22 _Z_

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Posted 12 February 2013 - 08:35 PM

H-Beta ?


H-Beta refers to filters which pass only the bluish Hydrogen-Beta (H-Beta) emission line at 4861 angstroms. A proper narrow-band nebula filter like the Lumicon UHC, Orion Ultrablock, or DGM Optics NPB will also pass the H-Beta line, but on the Horsehead, the contrast of the object tends to be quite a bit higher when using the H-Beta filter. The very first time I got to clearly see the Horsehead was around 1980 or so, using a 10 inch f/5 Newtonian equipped with the "brand-new" (at the time) Lumicon UHC filter. After seeing that, I went over to my own 8 inch f/7 Newtonian and put the UHC in that scope. Sure enough, I could just see the Horsehead, although not as well as in that 10 inch. On most decent dark nights now, I can get at least a glimpse of the Horsehead in my scopes using just a narrow-band filter, although again, it is far easier using my H-Beta filter. I have also seen the Horsehead without a filter in my 10 inch Newtonian, but the nights when that is possible are quite rare, and even then, I generally prefer the filtered view. Indeed, one night from my magnitude 5.6 driveway, I caught the Horsehead in my 9.25 inch SCT at 59x using the Lumicon H-Beta filter. Without that filter, there was no trace of it or of the background IC 434 nebulosity. Clear skies to you.



David, I think Leviathan was asking the OP if he used an h-beta filter.

-g


If that's the case, then yes I was, for all 3 of the h-beta oriented targets I went after (b33, california, flaming star).

#23 _Z_

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Posted 12 February 2013 - 08:36 PM

I saw IC434 last night for the first time, a dim hazy liver-shaped patch near Alnitak. I tried to spot the horsie, but alas.

Widespread, Are you sure you are looking at the correct nebula? The Flame Nebula, NGC 2024, looks more like a liver or a heart shaped fan east of Alnitak to me, but IC 434 looks like a line of nebulosity running south of Alnitak. If you take some time and continue looking at the Flame Nebula, maybe with some averted vision, you will see the dark nebula that gives this nebula it's name.

Zeldaboy, It is my experance that the darker and more transparent the sky is, the easier the nebula, IC 434, is to see. There have been a couple of really good nights in the last ten years that this nebula, IC 434 did appear much brighter than you normaly think when you think of it. I attribute this to a great night. Maybe that is what you experianced. Anyway, good catch.


That's exactly what we had, dark skies out over the chesapeake bay were easily mag 6 or better and transparency was a 5/5 after that huge front had just come through. We had one of the best winter milky ways naked eye views ever, with it clearly going down next to Canis Major and to the trees on the horizon.

#24 leviathan

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Posted 13 February 2013 - 01:09 AM

H-Beta ?


H-Beta refers to filters which pass only the bluish Hydrogen-Beta (H-Beta) emission line at 4861 angstroms. A proper narrow-band nebula filter like the Lumicon UHC, Orion Ultrablock, or DGM Optics NPB will also pass the H-Beta line, but on the Horsehead, the contrast of the object tends to be quite a bit higher when using the H-Beta filter. The very first time I got to clearly see the Horsehead was around 1980 or so, using a 10 inch f/5 Newtonian equipped with the "brand-new" (at the time) Lumicon UHC filter. After seeing that, I went over to my own 8 inch f/7 Newtonian and put the UHC in that scope. Sure enough, I could just see the Horsehead, although not as well as in that 10 inch. On most decent dark nights now, I can get at least a glimpse of the Horsehead in my scopes using just a narrow-band filter, although again, it is far easier using my H-Beta filter. I have also seen the Horsehead without a filter in my 10 inch Newtonian, but the nights when that is possible are quite rare, and even then, I generally prefer the filtered view. Indeed, one night from my magnitude 5.6 driveway, I caught the Horsehead in my 9.25 inch SCT at 59x using the Lumicon H-Beta filter. Without that filter, there was no trace of it or of the background IC 434 nebulosity. Clear skies to you.



David, I think Leviathan was asking the OP if he used an h-beta filter.

-g

Exactly. ;) My question was for Widespread, because IC434 in 90mm and without H-Beta is quite strange.

But thank you, David, for posting your experience.

#25 Widespread

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Posted 13 February 2013 - 07:24 AM

I saw IC434 last night for the first time, a dim hazy liver-shaped patch near Alnitak. I tried to spot the horsie, but alas.

Widespread, Are you sure you are looking at the correct nebula? The Flame Nebula, NGC 2024, looks more like a liver or a heart shaped fan east of Alnitak to me, but IC 434 looks like a line of nebulosity running south of Alnitak. If you take some time and continue looking at the Flame Nebula, maybe with some averted vision, you will see the dark nebula that gives this nebula .


I think you're right: it was the flame nebula that I saw. Sorry for the confusion.

Best,
David






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