This image includes almost all of the constellation of Orion, and the two bright nebulae near the centre of the loop are the well known Orion and Horsehead nebulae. It was made with a 4 x 5-inch view camera fitted with an Aero-Ektar lens attached to a tracking telescope. The exposure was 2 hours on a IIIa-F (red-sensitive) plate with a red filter.

This large and elusive feature is an emission nebula and is too faint to be seen with the unaided eye. It is about 10 degrees across and was first photographed in 1894 by Edward Barnard, a pioneering north American astro-photographer. It is significant that the loop is centred close to the two most active star-forming regions in this part of the sky, the Orion OB association, and it's likely that it marks the edge of stellar winds from most luminous stars.