NH3 was observed first in its lowest J = K = 1 tunneling transition toward Sagittarius B2 (Sgr B2):
A. C. Cheung, D. M. Rank, C. H. Townes, D. D. Thornton, and W. J. Welch,
Detection of NH<sub>3</sub> Molecules in the Interstellar Medium by Their Microwave Emission
Phys. Rev. Lett. 21, 1701–1705 (1968).
NH2D was detected initially toward Sgr B2 and Orion KL:
B. E. Turner, B. Zuckerman, M. Morris, and P.Palmer,
Microwave Detection of Interstellar Deuterated Ammonia
Astrophys. J. 219, L43–L47 (1978).
E. N. Rodriguez Kuiper, B. Zuckerman, and T. B. H. Kuiper,
Deuterated Ammonia Toward the Orion Nebula
Astrophys. J. 219, L49–L53 (1978).
15NH3 was observed toward the Orion Molecular Cloud (OMC-1) soon thereafter:
T. L. Wilson and T. Pauls,
The Detection of Interstellar <sup>15</sup>NH<sub>3</sub>
Astron. Astrophys. 73, L10–L12 (1979).
The first detection of a rotation-inversion transition of NH3 was also reported: J. Keene, G. A. Blake, and T. G. Philips,
First Detection of the Ground-State //J<sub>K</sub>// = 1<sub>0</sub> – 0<sub>0</sub> Submillimeter Transition of Interstellar Ammonia
Astrophys. J. 271, L27–L30 (1983).
NHD2 was detected first toward the L134N dark cloud which is also known as L183:
E. Roueff, S. Tiné, L. H. Coudert, G. Pineau des Forêts, E. Falgarone, and M. Gerin,
Detection of Doubly Deuterated Ammonia in L134N
Astron. Astrophys. 354, L63–L66 (2000).
Finally, even ND3 was detected in NGC 1333 and in the Barnard 1 Cloud:
F. F. S. van der Tak, P. Schilke, H. S. P. Müller, D. C. Lis, T. G. Phillips, M. Gerin, and E. Roueff,
Triply Deuterated Ammonia in NGC 1333
Astron. Astrophys. 388, L53–L56 (2002).
D. C. Lis, E. Roueff, M. Gerin, T. G. Phillips, L. H. Coudert, F. F. S. van der Tak, and P. Schilke,
Detection of Triply Deuterated Ammonia in the Barnard 1 Cloud
Astrophys. J. 571, L55–L58 (2002).
The detection of vibrationally excited NH3 (v2 = 1) was reported in:
R. Mauersberger, C. Henkel, and T. L. Wilson,
Vibrationally Excited Ammonia toward Orion-KL
Astron. Astrophys. 205, 235–242 (1988).
The observation of 111 (0+) – 101 (0–) ortho transition of 15NH2D with the IRAM 30m telescope toward Barnard-1b, NGC1333-DCO+, and L1689N was reported by:
M. Gerin, N. Marcelino, N. Biver, E. Roueff, L. H. Coudert, M. Elkeurti, D. C. Lis, and D. Bockelée-Morvan,
Detection of <sup>15</sup>NH<sub>2</sub>D in dense cores: a new tool for measuring the <sup>14</sup>N/<sup>15</sup>N ratio in the cold ISM
Astron. Astrophys. 498, L9–L12 (2009).
Contributor(s): H. S. P. Müller; 12, 2004; 06, 2006 & 01, 2010