NGC 1999 is a bright but tiny reflection nebula about 1.5° south-southeast of Orion Nebula M42 at a distance of about 1'500 lightyears. It shines by reflected starlight from V380 Orionis. A dark patch in front of the nebula has a size of ~10'000 AU (1/6 lightyear) and has the shape of a triangle.
The reflection nebula is part of a huge star forming region and is famous because the first Herbig-Haro (HH) objects discovered in 1946/1947. They are the result of fast-moving jets of material ejected from very young stars collide with the interstellar medium. HH1 is the bright object lower right of NGC 1999, HH2 about double the distance directly under the 'cosmic keyhole'.
There are many more such objects visible in this image documenting the high star forming activity in this region.
Telescope: RCOS 14.5" f/8
Mount: ASA DDM85
Filters: Astrodon Ha 5nm
Exposures: Ha 1200 min (30 min subs)