Barnard's Loop - the whole semicircle in binoculars
Some days ago I spend two nights to study Barnard's Loop. The question was - how long is the arc observable. I used a Nikon 8x30 EII binocular with two H? filters, which gave a single field of around 8.8?, which is around the half of the size of the whole Loop. Observing conditions were average, NELM around 6.5mag. The Loop was an easy target for the naked eye with the H? filters.
To my surprise, the loop was easily visible as a semicircle. Of course with the brightest part NE of M 78. Especially the straight arc part between Saiph and Rigel was visible without any problems. The fainter part was the extension to the NW starting from the brightest part, moving under ome Ori to 38 Ori. Saiph was open and limited by an arc to the NW, difficult to distinguish between the contrast phenomena from the star itself and the real arc.
M 42/43 were of course very bright to the H?. The reflection parts around NGC 1977 and NGC 2024 were also visible easily. The biggest challenge was the thin lane of IC 434. Bright in larger aperture, the lane was only barely visible, because of the small size unfavorable scale of only 8x magnification. Interestingly the star group down to the 6.2mag bright HD 37744 gave a nebulous character, but the "false" IC 434. The emission nebula was only visible as a 1' long, extremely faint line, interestingly with a harder edge to the western side.
What are your experiences with the Loop? How long could you observe the arc and what instrument do you use?
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