" Blue Horse Head" nebulas comlex

[Erik68]

My sketch of the"Blue Horse Head" nebulas complex and Sharpless 2-7 nebula. Set of several fields.
refractor 152/760
26x (field of view 3.2*)+ H beta SvBony(50nm)
NELM 6.6+mag.
transparency excellent

4731

[akarsh]

My sketch of the"Blue Horse Head" nebulas complex and Sharpless 2-1 nebula. Set of several fields.
refractor 152/760
26x (field of view 3.2*)+ H beta SvBony(50nm)
NELM 6.6+mag.
transparency excellent

4731

I am interested in trying to see this object and I put it on my observing list for this upcoming new moon. I'm wondering why you put the H-Beta filter in, because this complex seems like a mixture of emission, absorption (dark) and reflection nebulae. Did you also try to sketch it without the filter?

[Erik68]

At my place (50* latitude) the constellation Scorpio touches the horizon. Even with the excellent transparency, the sky is brightened, without filters something faint, but Sh 2-7 was not visible.
Only with H beta, I could see averted vision.
Dark nebulae I did not see, perhaps because of the small field of view(3*). They are really huge in this region.

[ScottH]

My sketch of the"Blue Horse Head" nebulas complex and Sharpless 2-1 nebula. Set of several fields.
refractor 152/760
26x (field of view 3.2*)+ H beta SvBony(50nm)
NELM 6.6+mag.
transparency excellent

4731

Hi Erik,

I like your sketch and am a bit amazed at how much detail you could see in IC 4592 (the Blue Horsehead) with only a 6" telescope from your latitude. But I have a problem. Sharpless 2-1 (also known as vdB 99) lies just below Pi Sco while Sharpless 2-7 is a long streak that lies between Delta Sco and Pi Sco. The only nebula that I know of that encompasses the star Delta Sco is Lynds' Bright Nebula (LBN) #1099, which happens to also include Sh 2-7. In fact, your drawing doesn't even show Pi Sco, so you can't say you saw Sh 2-1. Check out this image of the area by bucksnortobservatory (http://www.bucksnortobservatory.com/deepspace_pages/Vdb99.shtml). It shows the nebula that you drew around Delta Sco.

Scott H.

P.S. Since Erik posted his excellent sketch also on CloudyNights, I have replied with the same response there.

Scott

[Erik68]

My mistake, sorry!,Thanks Scott for the watchfulness. This is not Sh2-1,but Sh2-7.I'll correct that right away.
These nebulae are large, the field of view rules here, not the aperture.

[akarsh]

I'm very disoriented and unable to match the sketch with any field. Would you be able to explain which region this sketch is?

Yes, Erik, this agrees with my experience: for these low—surface brightness nebulosities, transparency and sky quality are more important than aperture. A more pedestrian example (given that's the extent of my experience with diffuse nebulae) is the Pleiades nebulosity, which I have enjoyed in a 25x100 binocular rather trivially from great skies, but is a tough challenge for any instrument if you aren't under those Bortle 1 or Bortle 2 conditions.

[ScottH]

I'm very disoriented and unable to match the sketch with any field. Would you be able to explain which region this sketch is?

Yes, Erik, this agrees with my experience: for these low—surface brightness nebulosities, transparency and sky quality are more important than aperture. A more pedestrian example (given that's the extent of my experience with diffuse nebulae) is the Pleiades nebulosity, which I have enjoyed in a 25x100 binocular rather trivially from great skies, but is a tough challenge for any instrument if you aren't under those Bortle 1 or Bortle 2 conditions.

North is up and east is to the right. The star with the disk of fuzzy glow around it in the lower left-hand corner is Delta Sco in the head of the Scorpion. The Blue Horsehead is in the upper right-hand corner.

In his final 1959 Catalogue, Sharpless described Sh 2-7 as having a maximum angular diameter of 240", irregular in form, between amorphous and filamentary in structure, and the faintest class found on the plates. So I'd say that you are probably seeing Sh 2-7 even though I've never heard of a visual observation of it! But since I'm currently chasing down all Sharpless nebulae, I really need to try for it! Thanks for posting your sketch, Erik.

[Erik68]

Akarsh
View from a refractor with diagonal, image is reversed.

Scott
Sh2-7 is a very difficult object to detect, and I could only do it thanks to the filter and excellent transparency, but I still detect it at the edge of perception.

[akarsh]

Ah, that makes sense, thanks Scott. I'm not used to mirrored fields of view since they seldom exist in the reflector world. I was able to match the field now, so I can actually appreciate Erik's sketch fully and it is very impressive! The accuracy of detail in the Blue Horsehead is quite amazing. And I agree with Scott, what Erik has in the sketch is Sh2-7.