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Davesellars

Horsehead Nebula questions

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OK..  So i'm intrigued from a couple of recent threads ;)  Perhaps I may attempt to go for this one this year if only to improve my observation / technique of faint nebulae!

First up: What's the approximate SQM-L or NELM of sky to begin to attempt this nebula or rather the starting points around it (Flame nebula and then IC434 before going on to attempting to see the HH "notch").  Dark adaption being paramount obviously although there are some local lights a few hundred yards away from my site I can block them out completely with a cloak to protect the eyes.  NELM on a really good transparent night will be 5.5 but normally around 5 to 5.2.   This would be observing with the 12" dob.

I do have a site I've visited but not observed from as yet that should be considerably darker as it's 5 or 6 miles away from the north of Oxford and no local lights within a mile.  The only catch is I'd be using much less aperture and would travel with my 120ST.  Still, for this kind of nebulae, darker skies are more important than significantly more aperture?  At this time of year I'd rather not be observing here though as I have to go by bike and with the icy conditions is most likely a really bad idea..... :p  So I think to start at my normal site with the dob and put up with protecting myself a bit more from any LP to garner better dark adaption.

er..  Any other tips?  I'd be interested to know your sky conditions for observing the Flame and IC434 and filters used etc

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I've tried many times for the HH dave. Thus far I've stuck to using my 12" dob. The HH has been seen with scopes as small as 4" I believe but the sky conditions have to be superb, no LP, very transparent, and the observers vision highly dark adapted.

Other than that I believe using an effective exit pupil, the right true field (cutting out the bright stars), a H-Beta filter to enhance the background nebulostity and knowing just where to look (important !) can all play a part in the whole thing.

I've been following this advice and got quite close on Saturday night (after many futile attempts with and without an h-beta filter):

http://www.skyhound.com/observing/archives/jan/IC_434.html

Here is another great observing link for this object:

http://www.perezmedia.net/beltofvenus/archives/000379.html

I love Jeremy Perez's description: " ....it's like trying to see a little bit of nothing with a little bit of less than nothing resting over it ...." :icon_biggrin:

Good luck and if you catch it before me I'll be very pleased for you :angryfire::smiley:

PS: I have another H-Beta filter on the way. I tried the Lumicon but gave up but that was me not trying hard enough and my skies rather than the filter I think. I'm going to try an ES H-B filter this time and see what gives with that one.

My best skies are around NELM 5.5. I can see quite a bit of the Milky Way and M31 / the double cluster naked eye on a good night.

 

Edited by John
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Many thanks John!  Both look great articles I'll give them a thorough go over.

Do you know what was your approx NELM?

Good luck yourself!  ...  I think this may be a long journey... :) It sounds like you're getting very close though so maybe next time!

 

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I've added what I think is my best NELM to the post above Dave - about 5.5. I might get a touch better overhead and on a great night. I did manage to see the East part of the Veil Nebula with my 11x70 bins and no filter once when it was right overhead.

What I need to do is to go somewhere where Orion's belt is overhead !

 

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Thanks.  That's good to know for a bit of reference.

Yes, we're somewhat disadvantaged in the UK with Orion really being too low down to make it that much more difficult!

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Hi Dave

My tips. Don't put too much emphasis on using a "horse head" eyepiece like some do. I have observed the HH with eyepieces from 12-31mm.

I have found the H-Beta is the best filter but an UHC will also work. It is doable with no filter from dark enough transparent skies.

It also is not as small as many expect looking more like a bay in the nebulosity that the 'notch' I've heard it described as. Look for a large bay not a tiny notch. 

I have only seen it from VLM6 skies or darker, thats not to say it cannot be done from poorer skies it's just I have not managed it......yet

Lastly, have fun. :) 

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7 minutes ago, swamp thing said:

Hi Dave

My tips. Don't put too much emphasis on using a "horse head" eyepiece like some do. I have observed the HH with eyepieces from 12-31mm.

I have found the H-Beta is the best filter but an UHC will also work. It is doable with no filter from dark enough transparent skies.

It also is not as small as many expect looking more like a bay in the nebulosity that the 'notch' I've heard it described as. Look for a large bay not a tiny notch. 

I have only seen it from VLM6 skies or darker, thats not to say it cannot be done from poorer skies it's just I have not managed it......yet

Lastly, have fun. :) 

Steve, is the reason that you place less emphasis on the eyepiece focal length related to the fact that you are using a 20" scope? Or have you seen it in smaller scopes?

I'm guessing that SQM and transparency are the key factors above all else?

Personally I've never even attempted it because I've never been in a position with the right scope and conditions for it to be worth it. One day perhaps...

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I got my first glimpse of the HH last night, using astronomik 2" Hb filter with my binos.

scope was CPC1100.

I first glimpsed it using delos17.3, the gas cloud was easily visible. I did try the previous night but had found the gas more of a challenge.

HH came in and out, had to keep starting again and tracing the gas path, there is a darker lane running within it that passes through the HH.

HH was larger than I imagined. Think I had been looking for something too small previously!

Also got some glimpses with the panoptic24 but the gas was less visible than with the Delos.

Surprisingly, I moved to try with the Hb filter on the Borg 89 and the gas lane seemed fairly visible with the Ethos13. I changed to a Delos10 for more mag but the clouds rolled in. Definitely will try this again to find out what the Borg is capable of?

Alan

 

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14 minutes ago, Stu said:

Steve, is the reason that you place less emphasis on the eyepiece focal length related to the fact that you are using a 20" scope? Or have you seen it in smaller scopes?

I'm guessing that SQM and transparency are the key factors above all else?

Personally I've never even attempted it because I've never been in a position with the right scope and conditions for it to be worth it. One day perhaps...

 

Perhaps using a 20" scope is one reason, BUT I have altered exit pupil many times observing this object and it does not disappear if one does this. It isn't that faint. It is tough but not as tough as some may think.

Yes dark sky and transparency is everything but then again........... it always is. ;) 

 

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I think Steve's experience results from the fast 20" and also very good skies, even using a 12mm eyepiece he still has an exit pupil of 3mm and huge image scale.He is also a very experienced observer that has "locked on" object recognition with this target.

My 15" also shows it very easy, and in this scope I prefer a UHC, my 10" likes a 25mm EP/Hb. I typically observe in 21.6+ skies with good transparency, but I have checked the HH down to about 21 mag in the 15", still do able. Personally I like lower mags and have tried higher ones- my opinion is that observer experience accommodates lower  exit pupils...and so do large fast scopes.

For someones first tries an exit pupil of 4.5mm-5.5mm might be good with a Hb and most importantly -dark transparent skies,IMHO.

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just for the record, i seen it the first time with my 14" dob, using a 13mm e and uhc filter. as steve says its a lot bigger than you think

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I have only seen the HH once and that was with a 16" Dob, Panoptic 19mm and 24mm EPs and a Hb Astronomik filter. I saw HH at Lucksall at a SGL star party. The skies at home are the same as Lucksall and I have always failed with my 10" Dob. Since last year I bought a 12" f5 Dob so I am hoping to try again.

I have a Thousand Oaks H.Beta and I am going to try with the 24mm end of my TeleVue zoom. I will also try with the Lumicon UHC.

I know I have listed this diagram before but it is what I use to try and the see the HH.

HH.location.jpg

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Great responses guys.  Many thanks.  I have an Astronomik UHC filter and a few suitable eyepieces. I'm on the lookout for the Astronomik Hb to add as well.

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I did try the Omega DGM NBP filter out on this target on Saturday night (the session where I thought I was close without a filter). The Flame neb stood out a little more as did NGC 2023. IC 435 looked fainter and I could not see the very faint elongated IC 434 any better than without the filter. I believe that seeing this nebula is the key to spotting the Horsehead because it's basically a bay that intrudes into / overlies IC 434 as I understand it.

I found the 24mm Panoptic (exit pupil 4.5mm) and the 17.3mm Delos (EP 3.26mm) effective on Saturday but I'm happy to experiment.

What a lot of fuss over seeing a bit of "nothing" ! :grin:

 

 

 

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33 minutes ago, John said:

What a lot of fuss over seeing a bit of "nothing" ! :grin:

It's a challenge... ;)   When you think about it, it's a bit strange when there are much more interesting objects to view... :)  It's more the build up to it though with the various nebulae around it of differing difficulty.  Seeing the HH may not be doable for me with my skies at the moment but you learn a bit more and it all comes in useful in observing other similar faint objects.

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I am in the "tiny notch" brigade as I use much shorter scopes than other people. It helps to have a good idea of the sort of size your scope will show so you are prepared and where it will fit within the stars you can see. I only go for it from dark locations to avoid frustration, transparency is key... check this with "easier" nebulae so you aren't wasting your time.

I would hate to think of what Steve thinks a "really tough" nebula is;-)

 

PEterW

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10 minutes ago, Davesellars said:

It's a challenge... ;)   When you think about it, it's a bit strange when there are much more interesting objects to view... :)  It's more the build up to it though with the various nebulae around it of differing difficulty.  Seeing the HH may not be doable for me with my skies at the moment but you learn a bit more and it all comes in useful in observing other similar faint objects.

I agree that the approaches that you use for these more challenging objects will pay dividends when observing others as well.

On the scale of the target in question (Peter's point) I've familliarised myself with the stars in the area and now have a reasonable idea of the likely scale of B33 I think. I'm prepared to be surprised though, all the same !

 

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1 hour ago, John said:

I did try the Omega DGM NBP filter out on this target on Saturday night (the session where I thought I was close without a filter). The Flame neb stood out a little more as did NGC 2023. IC 435 looked fainter and I could not see the very faint elongated IC 434 any better than without the filter. I believe that seeing this nebula is the key to spotting the Horsehead because it's basically a bay that intrudes into / overlies IC 434 as I understand it.

I found the 24mm Panoptic (exit pupil 4.5mm) and the 17.3mm Delos (EP 3.26mm) effective on Saturday but I'm happy to experiment.

What a lot of fuss over seeing a bit of "nothing" ! :grin:

As many of the excellent links you've posted above, HH benefits with filters with high H-beta transmission (a H-beta or UHC with high transmission in H-beta). DGM-NBP is an excellent filter, but looking at the transmission measurement here (and the comments afterwards)

http://www.cloudynights.com/topic/527199-spectroscopic-analysis-comparison-of-nebula-filters/?p=7134667

It has about 50% transmission in H-beta line, Dan McShane was there and didn't comment on possible defect filter or wrong measurement. Purely on those figures, I wouldn't rate DGM NPB as a top rate HH filter, just my £0.02

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I've checked the Astronomik UHC transmission give. For the Hbeta and seems to be in excess of 90% so a good place to start I guess... although with not quite so dark skies it may be that the Hbeta filter is necessary for improved contrast?

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16 minutes ago, Davesellars said:

I've checked the Astronomik UHC transmission give. For the Hbeta and seems to be in excess of 90% so a good place to start I guess... although with not quite so dark skies it may be that the Hbeta filter is necessary for improved contrast?

Good H-beta can sure help. Still, I'd like to think dark sky helps most. the vast majority, if not all,  who have seen HH are at NELM6 or much better sky.

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Make an attempt on the Horse Head nebula when Orion culminates. Full dark adaption and a period of hunting faint nebulae will further sharpen your senses. My recent experience at observing B33, I hadn't planned to yet at 2am, Orion was perfectly located and the sky was looking very crisp and no haze. I did not use a paracorr, so as to reduce too much glass in the light path. I used a 25mm (5.4mm exit pupil) and 20mm (4.34mm exit pupil) TV plossl, 14" F4.6 dob and 2" lumicon H-beta filter. When the eyepiece was aligned, I could make out the dim grey profile that is IC 434. In order to see the Horse Head required averted vision, the impression was immediately apparent and what struck me was how jet black it is. The drawing in Belt of Venus relates to my own encounter. The 20mm eyepiece provided the best contrast X80. I typically go dark sky observing in NELM 6 skies. I have got into the habit of using a SQM and access a variety of reasonable drive to locations North and West of Newcastle, readings range from between 20.95 to 21.4.

Initially, it is good to gain familiarity and to grow accustom to the star pattern, whether you see the Horse Head or not. Equally a period focused on The Flame and again familiarity in terms of what to expect / look for. I think that the Horse Head is quite achievable and once observed with confidence, I feel that this is an object you can go back to, if transparency is reasonable enough. 

 

 

 

Edited by scarp15
spell check
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40 minutes ago, scarp15 said:

 

.....I think that the Horse Head is quite achievable and once observed with confidence....

 

There is a lot in that - go in with a "can do" state of mind :icon_biggrin:

 

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1 hour ago, YKSE said:

..... I wouldn't rate DGM NPB as a top rate HH filter, just my £0.02

Nor would I Yong, having tried it, but on that night I only had that and an O-III in my case so I thought it worth a try. Nothing ventured, nothing gained as they say. As it happened the latter was the result of the DGM NBP filter but at least it's been tried now.

An ES H-Beta filter has just been delivered here so I'll give that a try next time out. It's light pass chart looks a little generous but it might do the trick :icon_biggrin:

 

 

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5 minutes ago, John said:

An ES H-Beta filter has just been delivered here so I'll give that a try next time out. It's light pass chart looks a little generous but it might do the trick :icon_biggrin:

 

 

John I will be interested how you get on. I notice that TH have the 1.25" filter for £39 and I was thinking of buying a second H.Beta  filter for my Apollo 15x70 binos - mainly for the California Nebula. Sorry for going away from the HH thread.

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21 minutes ago, John said:

There is a lot in that - go in with a "can do" state of mind :icon_biggrin:

 

Exactly, resilience and ''can do''.

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