Physical Properties

NGC 1999 is a reflection nebula in in the LDN 1641 portion of the Orion A GMC (giant molecular cloud). It lies at a distance of around 1350 light-years and has an estimated size of ~10'000 AU. At first one thought that NGC 1999 is something called a Bok globule – a dense, cold cloud of gas, molecules and cosmic dust from a star forming region that blocks background light. However, follow-up observation revealed that the dark patch is actually a hole or cavity in the material producing the NGC 1999 reflection nebula, excavated by protostellar jets from the V 380 Orionis quadruple system. ^{[638, 639]}

Finder Chart

The Nebula NGC 1999 is located in the constellation Orion, approximately 1.25° south of the famous Orion Nebula Messier 42 . It is best observed in the months of September to March.

Visual Observation

400 mm Aperture: NGC 1999 appears as a round, diffuse nebula around a bright star. At higher magnification (9 mm Nagler, 200x), a triangular, dark hole becomes visible next to the star. — 400 mm f/4.5 Taurus Dobsonian, Hasliberg, 16. 12. 2023, SQM-L 21.2, Bernd Nies

635 mm Aperture: Even at low magnification (35 mm Tele Vue Panoptic, 72x), a small nebula with a dark spot next to the center is visible around the 10.9 magnitude bright star BD -06°1253. With increasing magnification (10 mm Tele Vue Delos eyepiece, 254x), the contrast is optimal, and the key shape is clearly recognizable. The nebula is conspicuous and appears rich in detail. An unusual, often overlooked object. — 25" f/4 Obession Dobsonian, Astrofarm Tivoli, Namibia, 16. 9. 2023, Bernd Nies

762 mm Aperture: The nebula, which completely surrounds the star, shows visually and EAA-photographically close to the star a keyhole or a black spot of corresponding shape. Since the nebula surrounds the star to a very limited extent, one almost has the impression that the star itself contains the keyhole. — 30" SlipStream-Dobson f/3.3, Hasliberg, 16. 12. 2023, SQM-L 21.38, Eduard von Bergen