How to Approach, Barnard's Loop

[scarp15]

Sharpless 276, is a very large diffuse emission nebula of low surface brightness located in the constellation of Orion and can present a particular challenge for the seasoned deep sky observer.

To approach observing some aspects of this nebula, will require a wide field of view at low power. In perfect conditions, there are reports of seeing an expansive profile of this elliptical formed nebula, albeit very faint, naked eye or assisted with binoculars, by placing a H-beta filter in front of your eye or attaching to the binocular objectives. A fast 3" - 4"rich field refractor capable of yielding a 4 degree - 5 degree field is a favoured choice as is a 150mm - 200mm fast reflector, perhaps the preferred instrument to pursue this. As mentioned, a H-beta filter in 2" format is most applicable, yet sightings can be made with a UHC. Low power, large exit pupil, wide / ultra wide field eyepiece is required. 

To begin to consider attempting to observe Barnard's Loop, will require the observer to have gained experience and become accustomed to observing faint, subtle and diffuse nebulae, such as often referred to, the California Nebula in Perseus. Becoming competent in visually examining and responding to this large nebula, where there is little contrast between the subject and the sky background, will enable the observer to prepare mentally and visually in searching for yet more subtle, fainter subjects. Even so, repeated attempts drifting across a designated field may be necessary and can become quite tiring and straining. 

The easiest and brightest region to observe is within the northern section. Roughly begin to drift across from the reflection nebula M78 towards the open cluster NGC 2112. A very subtle broad grey contrast may be encountered as you immerse within the nebula, some averted vison might assist. Circumstances, a dark sky, very good transparency and complete dark adaption have to be in place.

There are experienced forum member observers, whom have focused much seasonal attention on Barnard's Loop and may most likely contribute into this topic. I have made attempts to observe Barnard's Loop with some success, past contributions by forum members have reassured and assisted. This has been with my 350mm dob, for this coming Orion season, I aim to employ using more my 200mm dob and 76mm refractor.

Please express: your aspirations or encounters, past observation experiences and perhaps plans of approach for the forth coming season towards attempting to define Barnard's Loop.  

[jetstream]

I'm thinking not many have seen this vast object. Excellent job viewing sections of it Iain , your good work shows that UK skies are more than capable on these faint objects.

[estwing]

Lovely write up and also a great read!...one on the list for Skye in November...clear skies!

[PeterW]

Fainter than the California, which could be a good warm up nebula (rises higher): Seeing Orion surrounded by the Loop, with the lambda orionis nebula on his shoulders, IC434 and M42 on his belt.. best sight for northern types.. sure the Vela area would be equally stunning if it ever rose for us!

Low power, wide angle viewing obligatory! Hoping to reacquaint myself with it soon. I’ll also be trying to ferret out the Eridanus Loop a “little to the right”.. which has evaded me. I have a new laser sight to help me better “get on target”, have to see if it works.

 

PeterW

[ollypenrice]

Great post. I have, with my pal Tom, devoted literally hundreds of hours to imaging it but I have never tried it in visual. I'll have a crack this winter. I must also try to dig out its history, but I very much doubt that the 'loop' concept precedes the camera. I'm sure sections of it will have been noted before the camera, though.

Olly

[PeterW]

Be interested in what you find, I’d expect Mr Herschel might have seen something, though his scope was like looking through a straw.... so he probably couldn’t appreciate the scale and shape.

its what I call a “big” nebula, really impressive if the conditions are good.

Peter

[scarp15]

17 hours ago, PeterW said:

Be interested in what you find, I’d expect Mr Herschel might have seen something, though his scope was like looking through a straw.... so he probably couldn’t appreciate the scale and shape.

its what I call a “big” nebula, really impressive if the conditions are good.

Peter

The history indicates that William Hershel quite probably did encounter, at least as you say something of this nebula in 1786. EE Barnard later in 1894 photographed and described this, coining the name Orion Loop. Reading further, the visible surface feature is considered to be an inner ionized surface of an even larger hydrogen cloud.

A clear advantage in having to travel to a dark location is the commitment once there for a potential 5 - 6hr duration session, if conditions are good. Considering how variable conditions can become in the UK, successive attention to a difficult subject such as this, might coincide with a period of optimum / favourable transparency. As you point out, Perseus will climb high, the California can then be visually regarded quite wholesome, more defined so not just cruising along the edge. There have been one or two previous accounts on here I think for attempting to trace the Eridanus Loop, such as Helix (she hasn't posted recently) good luck with that.

[clarkpm4242]

The Loop took me several years of attempts!  Failure due to inexperience, wrong instruments, conditions...

...I think my first 'oh yes!' view was from altitude in the caldera on Tenerife.  Dark sky, Orion riding high and a wide field refractor.  All subsequent observations have been with fast refractors.  Currently a TMB 92 SS f5.5, AP diagonal and 31 Nagler/13 Ethos with and without H beta filter.

I think that you do need the perfect night in the UK to give yourself a chance on a 1st view.  Star chart, optimum optics, dark adaptation, dark and the best transparency.  I have seen the Loop especially near M78 many times under imperfect conditions since.  Trying to find an 'edge' through a narrow field of view is not recommended!

Good luck...

...cheers Paul

[PeterW]

Keep at it, there’s lots to eek out!

https://www.mdwskysurvey.org/fullscreen-page/comp-iw2583if/b6ec6128-497f-4dec-aa35-a880eca29a6b/9/%3Fi%3D9%26p%3Daii2o%26s%3Dstyle-j40p46pn

 

Peter

[scarp15]

Good resource, the California visually shows up as two broad and long filaments, seen highlighted in the image.

I can but try and imagine that emphatic view Paul from Tenerife, after which becoming accustomed to observe the Loop, essentially near to M78 in UK conditions, particularly as described, involving specific equipment and circumstances.