Object of the Week June 16, 2024 - Barnard’s E

[Howard B]

Dark Nebula
Aquila
RA: 19 40 42
Dec: +10 57

870px-ENebulaHunterWilson.jpg
Barnard’s E – note that B143 is the northern, more distinctive part, with B142 below. Photo credit: Hunter Wilson


I'm excited to post about Barnard’s E, one of my new favorites. First described in E.E. Barnard’s 1919 paper, ON THE DARK MARKINGS OF THE SKY WITH A CATALOGUE OF 182 SUCH OBJECTS, the “E” is listed as items 142 and 143. (https://articles.adsabs.harvard.edu/...pJ....49....1B). The list was expanded in 1927 to include a total of 369 objects.

Interestingly, Barnard saw the “E” as we do today – perhaps he had a fondness for the letter that made it even easier to see. Regardless, the nebula is discontinuous, and has two designations; B142 and B143. Some might think it’s a bit of a stretch to see these two dark nebulae forming an “E”, but we can’t deny pareidolia, especially when viewed through a telescope. Here are Barnard’s descriptions from his 1919 paper – note the reference to “in E part” for 142:

“142: Large; irregular; about 40' E and W; BD +10 4016 in E part
143: Rather narrow, angular marking; the outline of a square 30' in diameter, with the W side missing.”

This is a relatively recent favorite object for me, because until the past few years I didn’t have telescopes with a wide enough field of view to properly frame both B142 and 143 – which span about a half degree altogether. I had my most spectacular view in 2022 using my 30-inch f/2.7 at its lowest magnifications of 80x (1.15-degree true field) and 113x (0.87-degree true field) on a decently dark, but wonderfully transparent night in the mountains of eastern Oregon:

“On a whim, I pointed the 30-inch at Barnard’s E – and wow, what a view! The three “horizontal” parts of the “E” are the most distinctive, with the connecting “vertical” parts less so. The edges of the more sharply delineated parts of the dark nebula are softly, and faintly illuminated, giving them a 3D appearance – just marvelous! 21.61 SQM (nearby B334, 336 and 337 look pretty awesome too!)”

Seeing the softly luminous edges is the most memorable thing about that observation, with the dense background of Milky Stars a close second. It was a magical view. In his 1919 paper, Barnard mentions seeing the faintly luminous edges of many dark nebulae, although he didn’t specifically call this out for 142 and 143.

On the same 2022 night as my 30-inch observation, I neglected to have a look with my 8-inch f/3.3, which I imagine would have been just as remarkable, placing B142 and 143 into their wider context. I’ve put this on my list for this summer, and will also see what a binocular view will show.

I think any telescope that can provide a true field of view of at least 0.75-degrees has a chance of showing Barnard’s E to good effect under a dark and transparent sky – so, give it a go and let us know!

[lamperti]

With a pair of 10x50 binoculars: "Both B-142 & B-143 are in the same field of binoculars. Opacity = 3 (B-143), Opacity = 4 (B-142). Relatively blank but not totally black. West of Altair."

[wvreeven]

With my old self-made 6" Newtonian telescope I observed these nebulae on August 5, 2005, from Southern France. I observed it with a 40 mm eye piece which IIRC was a Plössl eye piece so with a telescope focal length of 1020 mm the FOV must have been about 2º wide, maybe more. My notes read that there obviously are 2 nebulae. B 143 was shaped like a large C. B 142 was long and straight and larger than the FOV.