Cosmic Keyhole (NGC 1999)

NGC 1999
NGC 1999: Image taken with Hubble Space Telescope. © 1999 ESA/Hubble & NASA, ESO, K. Noll [638]
NGC 1999
NGC 1999: Section of the ESO/Digitized Sky Survey 2 © 2013 ESO, Davide De Martin [637]


This nebula was discovered by William Herschel on 5 October 1785 using his 18.7 inch reflector. He cataloged it as IV 33 and noted: «A star with milky chevelure or very bright nucleus with milky nebulosity.» [464] Dreyer added the nebula as NGC 1999 to his New General Catalogue published in 1888. [313]

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]

Revised+Historic NGC/IC Version 22/9, © 2022 Dr. Wolfgang Steinicke [277]
Designation NGC 1999
Type EN+RN
Right Ascension (J2000.0) 05h 36m 25.4s
Declination (J2000.0) -06° 42' 57"
Diameter 2 × 2 arcmin
Metric Distance 0.450 kpc
Identification, Remarks WH IV 33; GC 1202; LBN 979

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.

Finder Chart Cosmic Keyhole (NGC 1999)
Cosmic Keyhole (NGC 1999) in constellation Orion. Charts created using SkySafari 6 Pro and STScI Digitized Sky Survey. Limiting magnitudes: Constellation chart ~6.5 mag, DSS2 close-ups ~20 mag. [149, 160]

Visual Observation

NGC 1999
NGC 1999: EAA, roughly represents in black-white visual impression; 30" SlipStream-Dobson f/3.3 + Canon EOS R; 10s @ ISO 12'800; Hasliberg; © 16. 12. 2023 Eduard von Bergen [29]

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

Objects Within a Radius of 15°


  • [29] Astrobin: AstroEdy's Gallery;
  • [149] SkySafari 6 Pro, Simulation Curriculum;
  • [160] The STScI Digitized Sky Survey;
  • [277] «Historische Deep-Sky Kataloge» von Dr. Wolfgang Steinicke; (2021-02-17)
  • [313] «A New General Catalogue of Nebulae and Clusters of Stars, being the Catalogue of the late Sir John F.W. Herschel, Bart., revised, corrected, and enlarged» Dreyer, J. L. E. (1888); Memoirs of the Royal Astronomical Society. 49: 1–237; Bibcode:1888MmRAS..49....1D
  • [464] «Catalogue of a second thousand of new nebulae and clusters of stars; with a few introductory remarks on the construction of the heavens» William Herschel, Philosophical Transactions of the Royal Society of London, 1 January 1789; DOI:10.1098/rstl.1789.0021
  • [637] Wide-field view of part of Orion in visible light; (2023-08-31)
  • [638] Cosmic Keyhole; (2023-08-31)
  • [639] «Hier ist wahrhaftig ein Loch im Himmel – The NGC 1999 dark globule is not a globule» T. Stanke, A. M. Stutz, J. J. Tobin, B. Ali, S. T. Megeath, O. Krause, H. Linz, L. Allen, E. Bergin, N. Calvet, J. Di Francesco, W. J. Fischer, E. Furlan, L. Hartmann, T. Henning, P. Manoj, S. Maret, J. Muzerolle, P. C. Myers, D. Neufeld, M. Osorio, K. Pontoppidan, C. A. Poteet, D. M. Watson, T. Wilson; A&A, Volume 518, July-August 2010; DOI:10.1051/0004-6361/201014612