Sharpless 2 73 (Hercules)

Sh2-73 is a reflective nebula visible in the Hercules constellation. Originally exchanged for a HII region, it was discovered that it is illuminated by our galaxy as a whole, and is part of the so-called "Integrated Flux Nebulae" (IFNs). It is observed in the southwestern part of the constellation, at the border with the Head of the Snake and the Boreal Wreath; It appears as a very weak filament just perceptible in astronomical photos sensitive a Sh2-73 is one of the clouds closest to the solar system, being just 200 parsec away (about 650 light years); It is at a very high galactic latitude and does not appear associated with any luminous star, nor does it have stellar formation phenomena. The cloud could be associated with MBM 40, a weak unlined gas filament containing 20-40 M⊙ and about 120 parsec away from the Sun.