This is a list of molecules that have been the subject of unsuccessful astronomical searches in the interstellar or circumstellar media as well as claimed detections that have been soundly disconfirmed by subsequent work. A species may be detected in the future (i) in another source or (ii) with more sensitive observations or (iii) via different lines or (iv) in a different spectral regime. Note: Non-detections are ordered by the most recent unsuccessful search if multiple attempts have been reported.
Notes: (1) This is a work in progress and not a complete historical listing. Submissions are welcome!
Entries added in the last 1 or 2 months are highlighted in blue. (2) If a species is detected, then the entry
on this page is highlighted with gray background (and maintained for historical purposes.) (3) This page
does not track non-detections of detected molecules: molecules identified in one or more sources are often
not found in other sources.

YEAR
 SPECIES
 CITATION
 SOURCE, DETECTION LIMIT, AND LINES
1977 FCN
cyanogen fluoride

ASTROMOLECULE OF THE MONTH FOR APR 2018 		Detection of new interstellar transitions of H, OCS, and H2CO and a search for interstellar fluorine
J. M. Hollis and B. L. Ulick. ApJ 214:699-702 (1977) 		Orion A
NT < 1014 cm-2
J=2-1 (42216.64 MHz)
1981 CH(CN)3
cyanoform 		Searches for interstellar imidazole and cyanoform
W. M. Irvine, J. Ellder, Å. Hjalmarson, E. Kollberg, O. E. H. Rydbeck, G. O. Sørensen, B. Bak, and H. Svanholt. A&A 97:192-194 (1981) 		TMC-1, Ori A, etc.
N < 2-10 x 1013 cm-2
J = 6 → 5 (34379 MHz)
1981 H2SO4
sulfuric acid

ASTROMOLECULE OF THE MONTH FOR DEC 2017 		New interstellar molecular transitions in the 2 millimeter range
J. M. Hollis, L. E. Snyder, D. H. Blake, F. J. Lovas, R. D. Suenram, and B. L. Ulich. ApJ 251:541-548 (1981) 		Orion A, Sgr B2, W51, IRC +10216
1414,0-1313,0 (144278.9 MHz)
1414,1-1313,1 (144278.9 MHz)
1515,0-1414,0 (154594.7 MHz)
1515,1-1414,1 (154594.7 MHz)
1987 ClO
chlorine monoxide
Searches for interstellar and circumstellar metal oxides and chlorides
T. J. Millar, J. Eldér, Å. Hjalmarson, and H Olofsson, AA 182:143-149 (1987)
 IRC +10216
[X]/[H2] < 5x10-8
R Cas
[ClO]/[H2] < 2x10-6
2Π3/2, J=5/2-3/2
1987 CCl
carbon monochloride
Searches for interstellar and circumstellar metal oxides and chlorides
T. J. Millar, J. Eldér, Å. Hjalmarson, and H Olofsson, AA 182:143-149 (1987)
 Orion KL
[CCl]/[H2] < 2x10-10
IRC +10216
[CCl]/[H2] < 1x10-7
2Π1/2, J=5/2-3/2
1987 NaH
sodium hydride
A search for interstellar NaH and MgH in diffuse clouds
J. Czarny, P. Felenbok, and E. Roueff. A&A 188:155-158 (1987)
Prior non-detections:
A search for NaH in dense molecular clouds - evidence against formation on grains
R. L. Plambeck and N. R. Erickson. ApJ 262:606-610 (1982)
A search for interstellar NaH in diffuse clouds
T. P. Snow, Jr. and W. H. Smith. ApJ 217:68-70 (1977) 		ξ Oph, ζ Per
N(MgH) < 1.9 x 109 cm-2
A-X(8-0)R(0) band (3990.88 Å)
 Orion A
[NaH]/[H2] < 10-11
(and 4 other sources)
J = 1-0 (289.864 GHz)
ζ Oph, σ Sco
 A-X(8-0)R(0) band (3990.88 Å)
1991 NaOH
sodium hydroxide

ASTROMOLECULE OF THE MONTH FOR MAR 2024 		Oservations and chemistry of interstellar refractory elements
B. E. Turner. ApJ 376:573-298 (1991).
Detection of interstellar sodium hydroxide in self-adsoprtion toward the galactic center
J. M. Hollis and P. J. Rhodes. ApJ 262:L1-L5 (1987). 		Orion KL
N(NaOH) < 2.7 x 1013 cm-2
J=9-8 (226.123 GHz)
Sgr B2(OH)
J=4-3 (100.529 GHz)
1994 SiH2
silylene
Submillimeter molecular line observations of IRC +10216: Searches for MgH, SiH2, and HCO+, and detection of hot HCN
L. W. Avery, M. B. Bell, C. T. Cunningham, P. A. Feldman, R. H., Harward, J. M. McLeod, H. E. Matthews, and J. D. Wade. ApJ 426:737-741 (1994) 		IRC +10216
N(SiH2) ≤ 3.5 x 1015 cm-2
111-000 (353776 MHz
211-202 (305169 MHz
1994 MgF
magnesium momoflouride
Exotic Fluoride Molecules in IRC +10216: Confirmation of AlF and Searches for MgF and CaF
L. M. Ziurys, A. J. Apponi, and T. G. Phillips. ApJ 433:729-732 (1994) 		IRC +10216
N(MgF) < 0.4-1.8 x 1014 cm-2
6 transitions
1996 CH3C2NC
methyl-
isocyanoacetylene 		The search for methylisocyanoacetylene in TMC-1
F. Scappini, C. Codella, and A. Guarnieri. MNRAS 283:L7-L8 (1996) 		TMC-1
N(CH3C2NC) < 2.4x1012 cm-2
J = 7-6 and ...
K = 0 (30748.545 MHz)
K = 1 (30748.242 MHz)
1998 MgH
magnesium monohydride
A search for absorption of Mg and Ca compounds in molecular clouds towards Galactic continuum sources
S. Sakamoto, G. J. White, K. Kawaguchi, M. Ohishi, K. S. Usuda, and T. Hasegawa. MNRAS 301:872-880 (1998)
Prior non-detections:
Submillimeter molecular line observations of IRC +10216: Searches for MgH, SiH2, and HCO+, and detection of hot HCN
L. W. Avery, M. B. Bell, C. T. Cunningham, P. A. Feldman, R. H., Harward, J. M. McLeod, H. E. Matthews, and J. D. Wade. ApJ 426:737-741 (1994)
A search for interstellar NaH and MgH in diffuse clouds
J. Czarny, P. Felenbok, and E. Roueff. A&A 188:155-158 (1987) 		Sgr B2(M), W49A(N)
[MgH]/[H2] ≤ 1 x 10-11
6 lines
IRC +10216
N(MgH) ≤ 6 x 1012 cm-2
(J,F)=(1/2,1→1/2,0) (343117.463 MHz)
(J,F)=(3/2,2→1/2,1) (344305.125 MHz)
ξ Oph
N(MgH) < 1.9 x 109 cm-2
R1(1/2) line of the
A-X(0,0) band (5183.298 Å)
1998 MgO
magnesium oxide
A search for absorption of Mg and Ca compounds in molecular clouds towards Galactic continuum sources
S. Sakamoto, G. J. White, K. Kawaguchi, M. Ohishi, K. S. Usuda, and T. Hasegawa. MNRAS 301:872-880 (1998)
Prior non-detection:
Searches for interstellar and circumstellar metal oxides and chlorides
T. J. Millar, J. Eldér, Å. Hjalmarson, and H Olofsson, AA 182:143-149 (1987)
Prior tentative detection:
Interstellar MgO
B. E. Turner and T. C. Steimle, ApJ 299:956-966 (1985) 		Sgr B2(M), W49A(N)
[MgO]/[H2] ≤ 7.9 x 10-13
1-0 (34.298656 GHz)
3-2 (102.892416 GHz)
1998 MgOH
magnesium monohydroxide
A search for absorption of Mg and Ca compounds in molecular clouds towards Galactic continuum sources
S. Sakamoto, G. J. White, K. Kawaguchi, M. Ohishi, K. S. Usuda, and T. Hasegawa. MNRAS 301:872-880 (1998) 		Sgr B2(M), W49A(N)
[MgOH]/[H2] ≤ 1.6 x 10-10
4 lines
1998 CaH
calcium monohydride
A search for absorption of Mg and Ca compounds in molecular clouds towards Galactic continuum sources
S. Sakamoto, G. J. White, K. Kawaguchi, M. Ohishi, K. S. Usuda, and T. Hasegawa. MNRAS 301:872-880 (1998) 		Sgr B2(M), W49A(N)
[CaH]/[H2] ≤ 1.6 x 10-9
6 lines
1998 CaO
calcium oxide
A search for absorption of Mg and Ca compounds in molecular clouds towards Galactic continuum sources
S. Sakamoto, G. J. White, K. Kawaguchi, M. Ohishi, K. S. Usuda, and T. Hasegawa. MNRAS 301:872-880 (1998) 		Sgr B2(M), W49A(N)
[CaO]/[H2] ≤ 2.0 x 10-12
3-2 (79.646084 GHz)
4-3 (106.192569 GHz)
1998 CaOH
calcium monohydroxide
A search for absorption of Mg and Ca compounds in molecular clouds towards Galactic continuum sources
S. Sakamoto, G. J. White, K. Kawaguchi, M. Ohishi, K. S. Usuda, and T. Hasegawa. MNRAS 301:872-880 (1998) 		Sgr B2(M), W49A(N)
[CaOH]/[H2] ≤ 2.5 x 10-10
4 lines
2001 NH2SH
thiohydroxylamine
Searches for new interstellar molecules, including a tentative detection of aziridine and a possible detection of propenal
J. E. Dickens, W. M. Irvine, A. Nummelin, H. Møllendal, S. Saito, S. Thorwirth, and Å Hjalmarson. Spectrochimica Acta A 57:643-660 (2001) 		Various Sources
N(NH2SH) < 2-8 x 1013 cm-2
31,3-21,2
2004 HC4N
(bent) 		Detection of the Linear Radical HC4N in IRC +10216
J. Cernicharo, M. Guélin, and J. R. Pardo. ApJ 625:L145-L148 (2004) 		IRC +10216
N(X) < 3 x 1012 cm-2
(lines not provided)
2004 HC4N
(ringed) 		Detection of the Linear Radical HC4N in IRC +10216
J. Cernicharo, M. Guélin, and J. R. Pardo. ApJ 625:L145-L148 (2004) 		IRC +10216
N(X) < 3 x 1012 cm-2
(lines not provided)
2011
found in
2019 		HeH+
helium hydride ion
ASTROMOLECULE OF THE MONTH FOR JAN 2016 		A search for HeH+ and CH in a high-redshift quasi-stellar object
I. Zinchenko, V. Dubrovich, and C. Henkel. MNRAS 415:L76-L80 (2011)
An ISO Long Wavelength Spectrometer detection of CH in NGC 7027 and an HeH+ upper limit X.-W. Liu, M. J. Barlow, A. Dalgarno, J. Tennyson, T. Lim, B. M. Swinyard, J. Cernicharo, P. Cox, J.-P. Baluteau, D. Péquignot, Nguyen-Q-Rieu, R. J. Emery, and P. E. Clegg. MNRAS 290:L71-L75 		SDSS J114816.64+525150.3
(quasar)
J = 1 - 0 (2010.183873 GHz)
NGC 7027
(planetary nebula)
J = 1 - 0 (149.14 μm)
2012 CH3CH(NH2)CN
2-aminopropionitrile 		Rotational spectrum of a chiral amino acid precursor, 2-aminopropionitrile, and searches for it in Sagittarius B2(N)
H. Møllendal, L., Margulès, A. Belloche, R. A., Motiyenko, A. Konovalov, K. M. Menten, and J. C. Guillemin. A&A 538:A51 (2012) 		Sgr B2(N)
N(X) < 1.7 x 1016 cm-2
many lines
2013 CH2CHCH2NC
allyl isocyanide
The cm-, mm-, and sub-mm-wave Spectrum of Allyl Isocyanide and Radioastronomical Observations in Orion KL and the SgrB2 Line Surveys
I. Haykal, L. Margulès, T. R. Huet, R. A. Motyienko, P. Écija, E. J. Cocinero, F. Basterretxea, J. A. Fernández, F. Castaño, A. Lesarri, J. C. Guillemin, B. Tercero, and J. Cernicharo. ApJ 777:120 (2013) 		Orion KL
N(CH2CHCH2NH) < 3.3 x 1014 cm-2
many lines
2014 NeH+
neonium

ASTROMOLECULE OF THE MONTH FOR FEB 2016 		Ubiquitous argonium (ArH+) in the diffuse interstellar medium: A molecular tracer of almost purely atomic gas
P. Schilke, D. A. Neufeld, H. S. P. Müller, C. Comito, E. A. Bergin, D. C. Lis, M. Gerin, J. H. Black, M. Wolfire, N. Indriolo, J. C. Pearson, K. M. Menten, B. Winkel, Á. Sánchez-Monge, T. Möller, B. Godard, and E. Falgarone. A&A 566:A29 (2014) 		Sgr B2(M),(N)
[NeH+]/[ArH+] < 0.1
1-0 (1039.3 GHz)
2014 NH+
imidogen cation
Upper limits to interstellar NH+ and para-NH2- abundances. Herschel-HIFI observations towards Sgr B2 (M) and G10.6-0.4 (W31C)
C. M. Persson, M. Hajigholi, G. E. Hassel, A. O. H. Olofsson, J. H. Black, E. Herbst, H. S. P. Müller, J. Cernicharo, E. S. Wirström, M. Olberg, Å. Hjalmarson, D. C. Lis, H. M. Cuppen, M. Gerin, and K. M. Menten. A&A 567:A130 (2014) 		SgrB2(M), W31C
[NH+]/[H2] < 2 x 10-12, 4 x 10-13
J=1.5-0.5 fs (1013, 1019 GHz)
2014 para-NH2–
amino radial anion
Upper limits to interstellar NH+ and para-NH2- abundances. Herschel-HIFI observations towards Sgr B2 (M) and G10.6-0.4 (W31C)
C. M. Persson, M. Hajigholi, G. E. Hassel, A. O. H. Olofsson, J. H. Black, E. Herbst, H. S. P. Müller, J. Cernicharo, E. S. Wirström, M. Olberg, Å. Hjalmarson, D. C. Lis, H. M. Cuppen, M. Gerin, and K. M. Menten. A&A 567:A130 (2014) 		SgrB2(M), W31C
N(NH2-) < 4 x 1011 cm-2
11,1 - 00,0 (943 GHz)
2015 H3S+
sulfonium

ASTROMOLECULE OF THE MONTH FOR MAY 2017 		Sulphur-bearing molecules in diffuse molecular clouds: new results from SOFIA/GREAT and the IRAM 30 m telescope
D. A. Neufeld, B. Godard, M. Gerin, G. Pineau des Forêts, C. Bernier, E. Falgarone, U. U. Graf, R. Güsten, E. Herbst, P. Lesaffre, P. Schilke, P. Sonnentrucker, and H. Wiesemeyer. A&A 577:A49 (2015) 		W31C, G29.96-0.02, G34.3+0.1, W49N, W41
τ(H3S+)/τ(H2S) < 10-2
10 - 00 (293.4572 GHz)
2015 C4H6O2
vinyl acetate
Laboratory millimeter wave spectrum and astronomical search for vinyl acetate
L. Kolesniková, I. Peña, J. L. Alonso, J. Cernicharo, B. Tercero, and I. Kleiner. A&A 577:A91 (2015) 		Orion KL
N(vinyl acetate) < 4 x 1014 cm-2
Many lines
2016 H2S2
dihydrogen disulfide
The sulfur depletion problem: upper limits on the H2S2, HS2, and S2 gas-phase abundances toward the low-mass warm core IRAS 16293-2422
R. Martín-Doménech, I. Jiménez-Serra, G. M. Muñoz Caro, H. S. P. Müller, A. Occhiogrosso, L. Testi, P. M. Woods, and S. Viti. A&A 585:A112 (2016) 		IRAS 16293-2422
[H2S2]/[H2] < 8.1 x 10-9
12 lines from 223-336 GHz
2016
found in
2017 		HS2
monohydrogen disulfide
The sulfur depletion problem: upper limits on the H2S2, HS2, and S2 gas-phase abundances toward the low-mass warm core IRAS 16293-2422
R. Martín-Doménech, I. Jiménez-Serra, G. M. Muñoz Caro, H. S. P. Müller, A. Occhiogrosso, L. Testi, P. M. Woods, and S. Viti. A&A 585:A112 (2016) 		IRAS 16293-2422
[HS2]/[H2] < 1.1 x 10-8
5 lines from 252-334 GHz
2016 S2
disulfur
The sulfur depletion problem: upper limits on the H2S2, HS2, and S2 gas-phase abundances toward the low-mass warm core IRAS 16293-2422
R. Martín-Doménech, I. Jiménez-Serra, G. M. Muñoz Caro, H. S. P. Müller, A. Occhiogrosso, L. Testi, P. M. Woods, and S. Viti. A&A 585:A112 (2016) 		IRAS 16293-2422
[S2]/[H2] < 2.9 x 10-7
1110-99 (224.301 GHz)
1514-1313 (333.686 GHz)
2016 H2F+
fluoronium

ASTROMOLECULE OF THE MONTH FOR NOV 2016 		Detection of HF Toward PKS 1830-211, Search for Interstellar H2F+, and Laboratory Study of H2F+ and H2Cl+ Dissociative Recombination
K. Kawaguchi, S. Muller, J. H. Black, T. Amano, F. Matsushima, R. Fujimori, Y. Okabayahsi, H. Nagahiro, Y. Miyamoto, and J. Tang. ApJ 822:115 (2016) 		NGC 6334 I
[H2F+]/[H2Cl+] < 1/68
 PKS 1830-211
[H2F+]/[HF] < 1/386
110-101 (760.929 GHz)
[redshifted to 403.5 GHz in PKS 1820-211]
212-101 (1850.082 GHz)
2016 CH3NCO
acetonitrile oxide 		A rigorous detection of interstellar CH3NCO: An important missing species in astrochemical networks
J. Cernicharo, Z. Kisiel, B. Tercero, L. Kolesniková, I. R. Medvedev, A. López, S. Fortman, M. Winnewisser, F. C. de Lucia, J. L. Alonso, and J.-C. Guillemin. A&A 587:L4 (2016)		 Orion
N(CH3NCO) < 6 x 1013 cm-2
???
2016 HSO
hydrogen sulfoxy
Laboratory measurements and astronomical search for the HSO radical
G. Cazzoli, V. Lattanzi, T. Kirsch, J. Gauss, B. Tercero, J. Cernicharo, and C. Puzzarini. A&A 591:A126 (2016) 		Orion KL
N(HSO) < 1-4 x 1014 cm-2
Lines from 213.7-246.7 GHz
Sgr B2
N(HSO) < 1013 - 1016 cm-2
Lines from 7- 50 GHz
2016 CH3OCN
methyl cyanate
The millimeter wave spectrum of methyl cyanate: a laboratory study and astronomical search in space
L. Kolesniková, J. L. Alonso, C. Bermúdez, E. R. Alonso, B. Tercero, J. Cernicharo, and J.-C. Guillemin. A&A 591:A75 (2016)
A rigorous detection of interstellar CH3NCO: An important missing species in astrochemical networks
J. Cernicharo, Z. Kisiel, B. Tercero, L. Kolesniková, I. R. Medvedev, A. López, S. Fortman, M. Winnewisser, F. C. de Lucia, J. L. Alonso, and J.-C. Guillemin. A&A 587:L4 (2016) 		Orion KL, Sgr B2(N), B1-b, TMC-1
various upper limits
300 lines from 130 to 250 GHz
Orion
N(CH3OCN) < 1 x 1014 cm-2
300 lines from 130 to 250 GHz
2016 NCCOCN
carbonyl cyanide
Millimeter wave spectra of carbonyl cyanide
S. B. Bteich, B. Tercero, J. Cernicharo, R. A. Motiyenko, L. Margulès, and J.-C. Guillemin. A&A 592:A43 (2016) 		Orion KL
N(NCCOCN) < 5 x 1015 cm-2
Sgr B2(N)
N(NCCOCN) < 200 x 1015 cm-2
B1-b, TMC-1
various upper limits
1100 lines
2016 CH2CHOCHO
vinyl formate
Millimeter Wave Spectrum and Astronomical Search for Vinyl Formate
E. R. Alonso, L. Kolesniková, B. Tercero, C. Cabezas, J. L. Alonso, J. Cernicharo, and J.-C. Guillemin. ApJ 832:42 (2016) 		Orion KL, Sgr B2(N), TMC-1 ...
Orion: N(VF) < 1.5 x 1016 cm-2
2600 transitions from 80-360 GHz
2017
found in
2019 		HOCH2CN
glycolonitrile
Submillimeter spectra of 2-hydroxyacetonitrile (glycolonitrile; HOCH2CN) and its searches in GBT PRIMOS observations of Sgr B2(N)
L. Margulès, B. A. McGuire, M. L. Senent, R. A. Motiyenko, A. Remijan, and J. C. Guillemin. A&A 601:A50 (2017) 		Sgr B2(N)
N(X) < 1013-1015 cm-2
5000 lines
2017 CH3F
fluoromethane
Protostellar and cometary detections of organohalogens
E. C. Fayolle, K. I. Öberg, J. K. Jørgensen, K. Altwegg, H. Calcutt, H. S. P. Müller, M. Rubin, M. H. D. van der Wiel, P. Bjerkeli, T. L. Bourke, A. Coutens, E. F. van Dishoeck, M. N. Drozdovskaya, R. T. Garrod, N. F. W. Ligterink, M. V. Persson, S. F. Wampfler & the ROSINA team. Nature Astron 1:702-708 (2017).
Detection of new interstellar transitions of H, OCS, and H2CO and a search for interstellar fluorine
J. M. Hollis and B. L. Ulick. ApJ 214:699-702 (1977) 		IRAS 16293-2422
N(CH3F) < ~1013 cm-2
J'K-J"K=7K-6K,
K=0-3 (357 GHz)
Orion A
coincides with strong
H recombination line
JK=10-00 (51071.69 MHz)
2017
found in
2021 		HC11N
cyano-
pentaacetylene
ASTROMOLECULE OF THE MONTH FOR FEB 2014 		Deep K-band Observations of TMC-1 with the Green Bank Telescope: Detection of HC7O, Nondetection of HC11N, and a Search for New Organic Molecules
M. A. Cordiner, S. B. Charnley, Z. Kisiel, B. A. McGuire, and Y.-J. Kuan. ApJ 850:194 (2017)
Non-detection of HC11N towards TMC-1: constraining the chemistry of large carbon-chain molecules
R. A. Loomis, C. N. Shingledecker, G. Langston, B. A. McGuire, N. M. Dollhopf, A. M. Burkhardt, J. Corby, S. T. Booth, P. B. Carroll, B. Turner, and A. J. Remijan. MNRAS 463:4175 (2016)
Discomfirmed detection:
Detection of HC11N in the Cold Dust Cloud TMC-1
M. B. Bell, P. A. Feldman, M. J. Travers, M. C. McCarthy, C. A. Gottlieb, and P. Thaddeus, ApJ 483:L61-L64 (1997) 		TMC-1
N(HC11N) < ~1-4 x 1011 cm-2
J = 38-37 (12848.7 MHz)
J = 39-38 (13186.9 MHz)
J = 40-39 (13525.0 MHz)
J = 41-40 (13863.1 MHz)
J = 42-41 (14201.2 MHz)
J = 43-42 (14539.3 MHz)
J = 55-54 (18597.8 MHz)
J = 60-59 (20287.3 MHz)
2017 HC6O
hexatriynyloxy 		Deep K-band Observations of TMC-1 with the Green Bank Telescope: Detection of HC7O, Nondetection of HC11N, and a Search for New Organic Molecules
M. A. Cordiner, S. B. Charnley, Z. Kisiel, B. A. McGuire, and Y.-J. Kuan. ApJ 850:194 (2017) 		TMC-1
N(HC6O) < 1.5 x 1011 cm-2
12-11e (18828.319 MHz)
11-10e (18828.326 MHz)
12-11f (18829.311 MHz)
11-10f (18829.327 MHz)
13-12e (20465.490 MHz)
12-11e (20465.504 MHz)
13-12f (20466.662 MHz)
12-11f (20466.676 MHz)
2017 C6O
hexacarbon monoxide 		Deep K-band Observations of TMC-1 with the Green Bank Telescope: Detection of HC7O, Nondetection of HC11N, and a Search for New Organic Molecules
M. A. Cordiner, S. B. Charnley, Z. Kisiel, B. A. McGuire, and Y.-J. Kuan. ApJ 850:194 (2017) 		TMC-1
N(C6O) < 5.2 x 1010 cm-2
1112-1011 (19071.386 MHz)
2017 C7O
heptacarbon monoxide 		Deep K-band Observations of TMC-1 with the Green Bank Telescope: Detection of HC7O, Nondetection of HC11N, and a Search for New Organic Molecules
M. A. Cordiner, S. B. Charnley, Z. Kisiel, B. A. McGuire, and Y.-J. Kuan. ApJ 850:194 (2017) 		TMC-1
N(C7O) < 2.6 x 1010 cm-2
16-15 (18334.033 MHz)
17-16 (19479.903 MHz)
2017
found in
2024 		CH2(CN)2
malononitrile

ASTROMOLECULE OF THE MONTH FOR OCT 2020 		Deep K-band Observations of TMC-1 with the Green Bank Telescope: Detection of HC7O, Nondetection of HC11N, and a Search for New Organic Molecules
M. A. Cordiner, S. B. Charnley, Z. Kisiel, B. A. McGuire, and Y.-J. Kuan. ApJ 850:194 (2017) 		TMC-1
N(malononitrile) < 7.3 x 1010 cm-2
41,3-40,4 (19785.41 MHz)
2017 i-C9H7N
isoquinoline
Deep K-band Observations of TMC-1 with the Green Bank Telescope: Detection of HC7O, Nondetection of HC11N, and a Search for New Organic Molecules
M. A. Cordiner, S. B. Charnley, Z. Kisiel, B. A. McGuire, and Y.-J. Kuan. ApJ 850:194 (2017)
Astronomical searches for nitrogen heterocycles
S. B. Charnley, Y.-J. Kuan, H.-C. Huang, O. Botta, H. M. Butner, N. Cox, D. Despois, P. Ehrenfreund, Z. Kisiel, Y.-Y. Lee, A. J. Markwick, Z. Peeters, and S. D. Rodgers. Adv Space Res 36:137-145 (2005)
 TMC-1
N(isoquinoline) < 9.4 x 1011 cm-2
3 lines near 20529 MHz
IRC +10216, CRL 618, CRL 2688
N(Isoquin): various, < 1013 cm-2
a- and b-type quadruplets, J ≤ 73
2018 CH3ONH2
methoxyamine
Rotational spectrum of methoxyamine up to 480 GHz: a laboratory study and astronomical search
L. Kolesniková, B. Tercero, E. R. Alonso, J.-C. Guillemin, J. Cernicharo, and J. L. Alonso. A&A 609:A24 (2018). 		Orion KL, Sgr B2, B2-b, TMC-1
N(CH3ONH2) < ~1015 cm-2
many lines
2018 Z-HNCHCN
cyanomethanimine
Laboratory measurements and astronomical search for cyanomethanimine
M. Melosso, A. Melli, C. Puzzarini, C. Codella, L. Spada, L. Dore, C. Degli Esposti, B. Lefloch, R. Bachiller, C. Ceccarelli, J. Cernicharo, and V. Barone. A&A 609:A121 (2018). 		L1544, Barnard 1
[HNCHCN]/[H2] < 10-9-10-10
many lines
2018 C2H5NC
ethyl isocyanide

ASTROMOLECULE OF THE MONTH FOR AUG 2019 		Submillimeter wave spectroscopy of ethyl isocyanide and its searches in Orion
L. Margulès, B. Tercero, J. C. Guillemin, R. A. Motiyenko, and J. Cernicharo. A&A 610:A44 (2018) 		Orion KL
N(C2H5NC)/N(C2H5CN) < 0.003-0.007
many lines
2018 NH2CH2CH2CN
3-aminopropionitrile
Rotational spectrum of 3-aminopropionitrile and searches for it in Sagittarius B2(N)
C. Richard, A. Belloche, L. Margulès, R. A. Motiyenko, K. M. Menten, R. T. Garrod, and H. S. P. Müller. J Mol Spectrosc 345:51-59 (2018). 		Sgr B2(N)
N(syn form) < 8.1x1015 cm-2
N(anti form) < 1.3x1016 cm-2
many lines
2018 HBr
hydrogen bromide
Interstellar bromine abundance is consistent with cometary ices from Rosetta
N. F. W. Ligterink and M. Kama. A&A 619:A112 (2018) 		Orion KL, Sgr B2(N), NGC6334I
[HBr]/[H2] < 10-11-10-10
6 lines of H79Br and H81Br
near 500.6 GHz
2018 HBr+
hydrogen bromide cation
Interstellar bromine abundance is consistent with cometary ices from Rosetta
N. F. W. Ligterink and M. Kama. A&A 619:A112 (2018) 		Orion KL, Sgr B2(N), NGC6334I
[HBr+]/[H2] < ???
1188.2, 1662.7, 2136.8 GHz ???
2018 CH3CH2NCO
ethyl cyanate
Millimeter wave spectra of ethyl isocyanate and searches for it in Orion KL and Sagittarius B2
L. Kolesniková, E. R. Alonso, B. Tercero, J. Cernicharo, and J. L. Alonso. A&A 616:A173 (2018). 		Orion KL
N(CH3CH2NCO) < 5x1015 cm-2
 Sgr B2
N(CH3CH2NCO) < ~1x1016 cm-2
various lines
2018 NH2OH
hydroxylamine

ASTROMOLECULE OF THE MONTH FOR FEB 2015 		The ALMA-PILS survey: Stringent limits on small amines and nitrogen-oxides towards IRAS 16293-2422B
N. F. W. Ligterink, H. Calcutt, A. Coutens, L. E. Kristensen, T. L. Bourke, M. N. Drozdovskaya, H. S. P. Müller, S. F. Wampfler, M. H. D. van der Wiel, E. F. van Dishoeck, and J. K. Jørgensen. A&A 619:A28 (2018).
CSO and CARMA Observations of L1157. I. A Deep Search for Hydroxylamine (NH2OH)
B. A. McGuire, P. B. Carroll, N. M. Dollhopf, N. R. Crockett, J. F. Corby, R. A. Loomis, A. M. Burkhardt, C. Shingledecker, G. A. Blake, and A. J. Remijan. ApJ 821:76 (2015).
A Search for Hydroxylamine (NH2OH) toward Select Astronomical Sources
R. L. Pulliam, B. A. McGuire, and A. J. Remijan. ApJ 751:1 (2012) 		IRAS 16293-2422B
N(NH2OH) < 3.7 x 1014 cm-2
3 lines
L1157
N(NH2OH) < 1.5 x 1013 cm-2
12 lines
IRC+10216, Orion KL, Orion S, Sgr B2(N), Sgr B2(OH), W3IRS5, and W51M
N(NH2OH) < 2-8 x 1013 cm-2
14 lines
2018 C3H6O2
methoxyacetaldehyde
Laboratory rotational spectrum and astronomical search for methoxyacetaldehyde
L. Kolesniková, I. Peña, E. R. Alonso, B. Tercero, J. Cernicharo, S. Mata, and J. L. Alonso. A&A 619:A67 (2018) 		Orion KL
N(MA) < 5x1014 cm-2
 Sgr B2(N)
N(MA) < 50x1014 cm-2
 B1
N(MA) < 0.2x1014 cm-2
various lines
2018 CH3CHCO
methyl ketene

ASTROMOLECULE OF THE MONTH FOR JAN 2020 		The millimeter-wave spectrum of methyl ketene and the astronomical search for it
C. Bermúdez, B. Tercero, R. A. Motiyenko, L. Margulès, J. Cernicharo, Y. Ellinger, and J.-C. Guillemin. A&A 619:A92 (2018) 		Orion KL
N(MK) < 5-10x1014 cm-2
 Sgr B2(N)
N(MK) < 100x1014 cm-2
 B1-b, TMC-1
N(MK) < 0.001x1014 cm-2
various lines
2018 C4H10O2
1,2-butanediol
Millimeter-wave spectroscopy and modeling of 1,2-butanediol. Laboratory spectrum in the 59.6-103.6 GHz region and comparison with the ALMA archived observations
A. Vigorito, C. Calabrese, S. Melandri, A. Caracciolo, S. Mariotti, A. Giannetti, M. Massardi, and A. Maris. A&A 619:A140 (2018) 		IRAS 16293-2422
N(C4H10O2) < ? cm-2
various lines
2019 CH3SD
d-methyl mercaptan
Deuterated methyl mercaptan (CH3SD): Laboratory rotational spectroscopy and search toward IRAS 16293-2422 B
O. Zakharenko, F. Lewen, V. V. Ilyushin, M. N. Drozdovskaya, J. K. Jørgensen, S. Schlemmer, and H. S. P. Müller. A&A 621:A114 (2019) 		IRAS 16293-2422 B
N(CH3SH) < 8.8x1014 cm-2
12 "most-contraining" lines
2019 cis-HONO
nitrous acid

ASTROMOLECULE OF THE MONTH FOR SEP 2022 		The ALMA-PILS survey: First detection of nitrous acid (HONO) in the interstellar medium
A. Coutens, N. F. W. Ligterink, J.-C. Loison, V. Wakelam, H. Calcutt, M. N. Drozdovskaya, J. K. Jørgensen, H. S. P. Müller, E. F. van Dishoeck, and S. F. Wampfler. A&A 623:L13 (2019). 		IRAS 16293-2422 B
[X]/[H2] not reported
various lines (?)
2019 H215NCN
cyanamide
Laboratory spectroscopic study of the 15N isotopomers of cyanamide, H2NCN, and a search for them toward IRAS 16293-2422 B
A. Coutens, O. Zakharenko, F. Lewen, J. K. Jórgensen, S. Schlemmer, and H. S. P. M¨ller. A&A 623:A93 (2019) 		IRAS 16293-2422 B
N < 3x1013 cm-2
various lines
2019 H2NC15N
cyanamide
Laboratory spectroscopic study of the 15N isotopomers of cyanamide, H2NCN, and a search for them toward IRAS 16293-2422 B
A. Coutens, O. Zakharenko, F. Lewen, J. K. Jórgensen, S. Schlemmer, and H. S. P. Müller. A&A 623:A93 (2019) 		IRAS 16293-2422 B
N < 3x1013 cm-2
various lines
2019 C2H3SH
vinyl mercaptan
ASTROMOLECULE OF THE MONTH FOR AUG 2021 		Submillimeter spectroscopy and astronomical searches of vinyl mercaptan, C2H3SH
M.-A. Martin-Drumel, K. L. K. Lee, A. Belloche, O. Zingsheim, S. Thorwirth, H. S. P. Müller, F. Lewen, R. T. Garrod, K. M. Menten, M. C. McCarthy, and S. Schlemmer. A&A 623:A167 (2019) 		Sgr B2(N2)
N(X) < ~1016 cm-2
various lines
2019 CaF
calcium monofluoride
Discovery of the first Ca-bearing molecule in space: CaNC
J. Cernicharo, L. Velilla-Prieto, M. Agúndez, J. R. Pardo, J. P. Fonfría, G. Quintana-Lacaci, C. Cabezas, C. Bermúdez, and M. Guélin. A&A 627:L4 (2019)
Exotic Fluoride Molecules in IRC +10216: Confirmation of AlF and Searches for MgF and CaF
L. M. Ziurys, A. J. Apponi, and T. G. Phillips. ApJ 433:729-732 (1994) 		IRC +10216
N(CaF) < 1-3x1011 cm-2
various lines
IRC +10216
N(CaF) < 0.8-3.6 x 1014 cm-2
N = 11→10:
J=21/2→19/2 (225792 MHz)
J=23/2→21/2 (225830 MHz)
2019 CaCl
calcium monochloride
Discovery of the first Ca-bearing molecule in space: CaNC
J. Cernicharo, L. Velilla-Prieto, M. Agúndez, J. R. Pardo, J. P. Fonfría, G. Quintana-Lacaci, C. Cabezas, C. Bermúdez, and M. Guélin. A&A 627:L4 (2019)		 IRC +10216
N(CaF) < 1-3x1011 cm-2
various lines
2019 CaC
calcium monocarbide 		Discovery of the first Ca-bearing molecule in space: CaNC
J. Cernicharo, L. Velilla-Prieto, M. Agúndez, J. R. Pardo, J. P. Fonfría, G. Quintana-Lacaci, C. Cabezas, C. Bermúdez, and M. Guélin. A&A 627:L4 (2019)		 IRC +10216
N(CaF) < 1-3x1011 cm-2
various lines
2019 CaCCH
calcium monoacetylide 		Discovery of the first Ca-bearing molecule in space: CaNC
J. Cernicharo, L. Velilla-Prieto, M. Agúndez, J. R. Pardo, J. P. Fonfría, G. Quintana-Lacaci, C. Cabezas, C. Bermúdez, and M. Guélin. A&A 627:L4 (2019)		 IRC +10216
N(CaF) < 1-3x1011 cm-2
various lines
2019 CaCH3
calcium monomethylide 		Discovery of the first Ca-bearing molecule in space: CaNC
J. Cernicharo, L. Velilla-Prieto, M. Agúndez, J. R. Pardo, J. P. Fonfría, G. Quintana-Lacaci, C. Cabezas, C. Bermúdez, and M. Guélin. A&A 627:L4 (2019)		 IRC +10216
N(CaF) < 1-3x1011 cm-2
various lines
2019 NH2CSCH3
thioacetamide
Laboratory Measurements and Astronomical Search for Thioacetamide
A. Maris, C. Calabrese, L. B. Favero, L. Evangelisti, I. Usabiaga, S. Mariotti, C. Codella, L. Podio, N. Balucani, C. Ceccarelli, B. LeFloch, and S. Melandri. ACS Earth Space Chem 3:1537-1549 (2019) 		L1544, L1157B1
[NH2CSCH3]/[H2] < 4x10-11,10-12
various lines
2019 LiC3N
lithium cyanoacetylide
ASTROMOLECULE OF THE MONTH FOR FEB 2022 		Alkaline and alkaline-earth cyanoacetylides: A combined theoretical and rotational spectroscopic investigation
C. Cabezas, C. Barrientos, A. Largo, J.-C. Guillemin, J. Cernicharo, and J. L. Alonso. J Chem Phys 151, 054312 (2019). 		IRC +10216
N(LiCCCN) < 8x1010 cm-2
mm transitions similar
to NaCCCN
2019 NaC3N
sodium cyanoacetylide 		Alkaline and alkaline-earth cyanoacetylides: A combined theoretical and rotational spectroscopic investigation
C. Cabezas, C. Barrientos, A. Largo, J.-C. Guillemin, J. Cernicharo, and J. L. Alonso. J Chem Phys 151, 054312 (2019). 		IRC +10216
N(NaCCCN) < 8x1010 cm-2
mm transitions J=27-26
through J=44-43
2019 C4H4N2
succinonitrile
The millimeter-wave spectrum and astronomical search of succinonitrile and its vibrational excited states
C. Cabezas, C. Bermúdez, J. D. Gallego, B. Tercero, J. M. Hernández, I. Tanarro, V. J. Herrero, J. L. Doménech and J. Cernicharo. A&A 629:A35 (2019) 		Orion KL
N(suc) < 0.1x1014 cm-2
 Sgr B2(N)
N(suc) < 100x1014 cm-2
 B1-b
N(suc) < 12x1014 cm-2
 TMC-1
N(suc) < 0.0020x1014 cm-2
various lines of the ground state
and vibrationally excited states
2019 CH313C(O)CH3
13C-acetone
Laboratory rotational spectroscopy of isotopic acetone, CH313C(O)CH3 and 13CH3C(O)CH3, and astronomical search in Sagittarius B2(N2)
M. H. Ordu, O. Zingsheim, A. Belloche, F. Lewen, R. T. Garrod, K. M. Menten, S. Schlemmer, and H. S. P. Müller. A&A 629:A72 (2019) 		Sgr B2(N2)
N(X) < 1.5x1016 cm-2
various lines
2019 CH3CH(OH)CH(O)
lactaldehyde
The Laboratory Millimeter and Submillimeter Rotational Spectrum of Lactaldehyde and an Astronomical Search in Sgr B2(N), Orion-KL, and NGC 6334I
E. R. Alonso, B. A. McGuire, L. Kolesniková, P. B. Carroll, I. León, C. L. Brogan, T. R. Hunter, J.-C. Guillemin, and J. L. Alonso. ApJ 883:18 (2019) 		>10 Sources
(upper limits source-dependent)
various lines
2019
found in
2021 		H2CCS
thioketene

ASTROMOLECULE OF THE MONTH FOR JUL 2021 		Searches for Interstellar HCCSH and H2CCS
B. A. McGuire, C. N. Shingledecker, E. R. Willis, K. L. K. Lee, M.-A. Martin-Drumel, G. A. Blake, C. L. Brogan, A. M. Burkhardt, P. Caselli, K.-J. Chuang, S. El-Abd, T. R. Hunter, S. Ioppolo, H. Linnartz, A. J. Remijan, C. Xue, and M. C. McCarthy. ApJ 883:201 (2019) 		>10 Sources
(upper limits source-dependent)
various lines
2019 HCCSH
ethynethiol

ASTROMOLECULE OF THE MONTH FOR OCT 2023 		Searches for Interstellar HCCSH and H2CCS
B. A. McGuire, C. N. Shingledecker, E. R. Willis, K. L. K. Lee, M.-A. Martin-Drumel, G. A. Blake, C. L. Brogan, A. M. Burkhardt, P. Caselli, K.-J. Chuang, S. El-Abd, T. R. Hunter, S. Ioppolo, H. Linnartz, A. J. Remijan, C. Xue, and M. C. McCarthy. ApJ 883:201 (2019) 		>10 Sources
(upper limits source-dependent)
various lines
2020
found in
2021 		C6H4
benzyne

ASTROMOLECULE OF THE MONTH FOR APR 2021 		Benzyne in V4334 Sqr: A Quest for the Ring with SOFIA/EXES
C. E. Woodward, A. Evans, M. Richter, C. N. DeWitt, E. Montiel, D. P. K. Banerjee, G. C. Clayton, S. P. S. Eyres, R. D. Gehrz, and K. H. Hinkle. AJ 159:87 (2020.
A Search for ortho-benzyne (o-C6H4) in CRL 618.
S. L. Widicus Weaver, A. J. Remijan, R. J. McMahon, and B. J. McCall. ApJ 671:L153 (2007). 		V4334 Sgr
18.16 μm
CRL 618
N(C6H4) < 8.4 x 1013 cm-2
various rotational lines
2020 NC-(CH2)3-CN
glutaronitrile

ASTROMOLECULE OF THE MONTH FOR SEP 2020 		Rotational spectroscopy and astronomical search for glutaronitrile
C. Cabezas, C. Bermúdez, Y. Endo, B. Tercero, and J. Cernicharo. A&A 636:A33 (2020) 		ORION KL, Sgr B2(N), B1-b, TLC-1
N(C5H6N2) < 1-100x1015 cm-2
111 lines
2020 13CH3SH
13C-sub methanethiol
Rotational spectrum of isotopic methyl mercaptan, 13CH3SH, in the laboratory and towards Sagittarius B2(N2)
V. V. Ilyushin, O. Zakharenko, F. Lewen, S. Schlemmer, E. A. Alekseev, M. Pogrebnyak, R. M. Lees, L.-H. Xu, A. Belloche, K. M. Menten, R. T. Garrod, and H. S. P. Müller. Can J Phys 98, 530-537 (2020). 		Sgr B2(N)
various lines - all blended
with other molecules
2020 NCCHCO
cyanoketene
Millimeter wave spectroscopy of cyanoketene (NC-CH=C=O) and an observational search in the ISM
L. Margulès, B. A. McGuire, R. A. Motiyenko, C. Brogan, T. Hunter, A. Remijan, and J. C. Guillemin. A&A 638, A3 (2020). 		various sources/upper limits
1549 transitions
2020 CH3CHS
thioacetaldehyde
Submillimeter-wave spectroscopy of and interstellar search for thioacetaldehyde
L. Margulès, V. V. Ilyushin, B. A. McGuire, A. Belloche, R. A. Motiyenko, A. Remijan, E. A. Alekseev, O. Dorovskay, and J.-C. Guillemin. J Mol Spectrosc 371:111304 (2020) 		Sgr B2(n), prestellar/protostellar sources
various lines
2020 C2H5SCH3
ethyl methyl sulfide
The millimeter-wave spectrum and astronomical search for ethyl methyl sulfide
C. Cabezas, C. Bermúdez, B. Tercero, and J. Cernicharo. A&A 639:A129 (2020) 		Sgr B2(n), Orion KL, B1-b, TMC-1
various lines
2020
found in
2023 		CH2(OH)C(O)NH2
glycolamide
Interstellar glycolamide: A comprehensive rotational study and an astronomical search in Sgr B2(N)
M. Sanz-Novo, A. Belloche, J. L. Alonso, L. Kolesniková, R. T. Garrod, S. Mata, H. S. P. Müller, K. M. Menten, and Y. Gong. A&A 639:A135 (2020) 		Sgr B2(N2)
various lines
2020 E-HNCHCCH
E-propargylimine 		Propargylimine in the laboratory and in space: millimetre-wave spectroscopy and its first detection in the ISM
L. Bizzocchi, D. Prudenzano, V. M. Rivilla, A. Pietropolli-Charmet, B. M. Giuliano, P. Caselli, J. Martín-Pintado, I. Jiménez-Serra, S. Martín, M. A. Requena-Torres, F. Rico-Villas, S. Zeng and J.-C. Guillemin. A&A 640:A98 (2020). 		G+0.693-0.027
[E-HNCHCCH]/[H2] < 1.8x10-10
various lines
2020 HC6NC
isocyano triacetylene 		Detection of Interstellar HC4NC and an Investigation of Isocyanopolyyne Chemistry under TMC-1 Conditions
C. Xue, E. R. Willis, R. A. Loomis, K. L. K. Lee, A. M. Burkhardt, C. N. Shingledecker, S. B. Charnley, M. A. Cordiner, S. Kalenskii, M. C. McCarthy, E. Herbst, A. J. Remijan, and B. A. McGuire. ApJL 900:L9 (2020).
Discovery of HC4NC in TMC-1: A study of the isomers of HC3N, HC5N, and HC7N
J. Cernicharo, N. Marcelino, M. Agúndez, C. Bermúdez, C. Cabezas, B. Tercero, and J. R. Pardo. A&A 642:L8 (2020).		 TMC-1
N < 9.0x1010 cm-2
 IRC +10216
N < 2.0x1011 cm-2
various transitions
2020 SiH
silylidyne
A Search for Light Hydrides in the Envelopes of Evolved Stars
M. A. Siebert, I. Simon, C. N. Shingledecker, P. B. Carroll, A. M. Burkhardt, S. T. Booth, A. J. Remijan, B. A. McGuire, R. Aladro, and C. A. Duran. ApJ 901:22 (2020). 		IRC+10216
[SiH]/[H2] < 3x10-7
 VY CMa
[SiH]/[H2] < 3x10-5
J=3/2-1/2
J=5/2-3/2
2020 PH
phosphineidene
A Search for Light Hydrides in the Envelopes of Evolved Stars
M. A. Siebert, I. Simon, C. N. Shingledecker, P. B. Carroll, A. M. Burkhardt, S. T. Booth, A. J. Remijan, B. A. McGuire, R. Aladro, and C. A. Duran. ApJ 901:22 (2020). 		IRC+10216
[PH]/[H2] < 4x10-8
N=3=2, J=4-3
2020 FeH
iron monohydride
A Search for Light Hydrides in the Envelopes of Evolved Stars
M. A. Siebert, I. Simon, C. N. Shingledecker, P. B. Carroll, A. M. Burkhardt, S. T. Booth, A. J. Remijan, B. A. McGuire, R. Aladro, and C. A. Duran. ApJ 901:22 (2020). 		IRC+10216
[FeH]/[H2] < 2x10-7
 VY CMa
[FeH]/[H2] < 3x10-8
Ω=5/2, J=5/2-7/2
2020 C3H4N2O
2-amino-oxazole
Toward the RNA-World in the Interstellar Medium-Detection of Urea and Search of 2-Amino-oxazole and Simple Sugars
I. Jiménez-Serra, J. Martín-Pintado, V. M. Rivilla, L. Rodríguez-Almeida, E. R. Alonso Alonso, S. Zeng, E. J. Cocinero, S. Martín, M. Requena-Torres, R. Martín-Domenech, and L. Testi. Astrobio 20:1048-1066 (2020). 		G+0.693-0.027
various lines
2020 HOCH2CHO
glyceraldehyde
Toward the RNA-World in the Interstellar Medium-Detection of Urea and Search of 2-Amino-oxazole and Simple Sugars
I. Jiménez-Serra, J. Martín-Pintado, V. M. Rivilla, L. Rodríguez-Almeida, E. R. Alonso Alonso, S. Zeng, E. J. Cocinero, S. Martín, M. Requena-Torres, R. Martín-Domenech, and L. Testi. Astrobio 20:1048-1066 (2020). 		G+0.693-0.027
various lines
2020 NH2CHS
thioformamide
Millimeter- and submillimeter-wave spectroscopy of thioformamide and interstellar search toward Sgr B2(N)
R. A. Motiyenko, A. Belloche, R. T. Garrod, L. Margulès, H. S. P. Müller, K. M. Menten, and J.-C. Guillemin. A&A 642:A29 (2020) 		Sgr B2(N)
N(X) < 4.2 x 10-15 cm-2
various transitions
2020 HCCCHS
propynethial 		Submillimeter-wave spectroscopy and the radio-astronomical investigation of propynethial (HC≡CCHS)
L. Margulès, B. A. McGuire, C. J. Evans, R. A. Motiyenko, A. Remijan, J. C. Guillemin, A. Wong, and D. McNaughton. A&A 642:A206 (2020) 		11 sources
various lines
2021 (CH3)2CHNCS
isopropyl isothiocyanate
High-Resolution Rotational Spectroscopy and Interstellar Search for Isopropyl Isothiocyanate
Y. Xu, J. Zhang, W. Li, J. Li, and G. Feng. ACS Earth Space Chem 5:33-39 (2021). 		Sgr B2(N)
[(CH3)2CHNCS]/[H2] < 8x10-12
various lines
2021 c-C3H5CHO
cyclopropane-
carboxaldehyde
Comprehensive rotational study and astronomical search for cyclopropanecarboxaldehyde
C. Cabezas, E. M. Neeman, B. Tercero, C. Bermúdez, and J. Cernicharo. A&A 645, A175 (2021). 		Orion KL (HC, MM4)
N(CH3CHO)/N(CPCA) > 2
Sgr B2
N(CH3CHO)/N(CPCA) > 4
various lines
2021 HCCC(O)NH2
propiolamide 		Rotational spectroscopic study and astronomical search for propiolamide in Sgr B2(N)
E. R. Alonso, L. Kolesniková, A. Belloche, S. Mata, R. T. Garrod, A. Jabri, I. León, J.-C. Guillemin, H. S. P. Müller, K. M. Menten, and J. L. Alonso. A&A 647:A55 (2021) 		Sgr B2(N)
various lines
2021 CH3CH2COOH
propanoic acid
Submillimeter wave spectroscopy of propanoic acid (CH3CH2COOH) and its ISM search
V. V. Ilyushin, L. Margulès, B. Tercero, R. A. Motiyenko, O. Dorovskaya, E. A. Alekseev, E. R. Alonso, L. Kolesniková, J. Cernicharo, and J. C. Guillemin. J Mol Spectrosc 379:111454 (2021). 		Orion KL hot core
N < 2x1015 cm-2
 Sgr B2
N < 10-20x1015 cm-2
various lines
2022 CH3C8H
methyltetra-
acetylene 		CH3-Terminated Carbon Chains in the GOTHAM Survey of TMC-1: Evidence of Interstellar CH3C7
M. A. Siebert, K. L. K. Lee, A. J. Remijan, A. M. Burkhardt, The GOTHAM Collaboration, R. A. Loomis, M. C. McCarthy, and B. A. McGuire. ApJ 924:21 (2022). 		TMC-1
N(MTA) < ~1011 cm-2
multiple lines
2022 NH2CH2C(O)NH2
glycinamide
Millimetre-wave laboratory study of glycinamide and a search for it with ALMA towards Sagittarius B2(N)
Z. Kisiel, L. Kolesniková, A. Belloche, J.-C. Guillemin, L. Pszczółkowski, E. R. Alonso, R. T. Garrod, E. Białkowska-Jaworska, I. León, H. S. P. Müller, K. M. Menten, and J. L. Alonso. A&A 657:A99 (2022). 		Sgr B2(N)
N(glycinaimde) < 1.5x1016 cm-2
various lines
2022 HCCCHCN
1-cyano propargyl
radical 		Laboratory observation and astronomical search of 1-cyano propargyl radical, HCCCHCN
C. Cabezas, M. Nakajima, C. H. Chang, M. Agúndez, Y. Endo, and J. Cernicharo. A&A 657:A24 (2022). 		TMC-1
N(HCCCHCN) < 6.0x1011 cm-2
22 transitions
2022 CH3CSNH2
thioacetamide
Expanding the submillimeter wave spectroscopy and astronomical search for thioacetamide (CH3CSNH2) in the ISM
A. Remijan, C. Xue, L. Margulès, A. Belloche, R. A. Motiyenko, J. Carder, C. Codella, N. Balucani, C. L. Brogan, C. Ceccarelli, T. R. Hunter, A. Maris, S. Melandri, M. Siebert, and B. A. McGuire. A&A 658:A85 (2022). 		Sgr B2(N),NGC 6334l,
L1544, L1157-B1
various lines & detection limits
2022 syn-CH2CHC(O)NH2
acrylamide
Laboratory rotational spectroscopy of acrylamide and a search for acrylamide and propionamide toward Sgr B2(N) with ALMA
L. Kolesniková, A. Belloche, J. Koucký, E. R. Alonso, R. T. Garrod, K. Luková, K. M. Menten, H. S. P. Müller, P. Kania, and Š. Urban. A&A 659:A111 (2022). 		Sgr B2(N)>
N(acrylamide) < 1.6x1016 cm-2
various lines
2022 C2H3CHO
vinyl formate
The ALMA-PILS survey: First tentative detection of 3-hydroxypropenal (HOCHCHCHO) in the interstellar medium and chemical modeling of the C3H4O2 isomers
A. Coutens, J.-C. Loison, A. Boulanger, E. Caux, H. S. P. Müller, V. Wakelam, S. Manigand, and J. K. Jørgensen. A&A 660:L6 (2022). 		IRAS 16293-2422B
N(X) < 4x1015 cm-2
various lines
2022 C2H3COOH
propenoic acid
The ALMA-PILS survey: First tentative detection of 3-hydroxypropenal (HOCHCHCHO) in the interstellar medium and chemical modeling of the C3H4O2 isomers
A. Coutens, J.-C. Loison, A. Boulanger, E. Caux, H. S. P. Müller, V. Wakelam, S. Manigand, and J. K. Jørgensen. A&A 660:L6 (2022). 		IRAS 16293-2422B
N(X) < 1-4x1015 cm-2
various lines
2022 c-C2H3N
2H-azirine
A Search for Heterocycles in GOTHAM Observations of TMC-1
T. J. Barnum, M. A. Siebert, K. L. K. Lee, R. A. Loomis, P. B. Changala, S. B. Charnley, M. L. Sita, C. Xue, A. J. Remijan, A. M. Burkhardt, B. A. McGuire, and I. R. Cooke. J Phys Chem A 126:2716-2728 (2022). 		TMC-1
N(X) < 2x1013 cm-2
various lines
2022 c-C2H5N
aziridine

ASTROMOLECULE OF THE MONTH FOR AUG 2022 		A Search for Heterocycles in GOTHAM Observations of TMC-1
T. J. Barnum, M. A. Siebert, K. L. K. Lee, R. A. Loomis, P. B. Changala, S. B. Charnley, M. L. Sita, C. Xue, A. J. Remijan, A. M. Burkhardt, B. A. McGuire, and I. R. Cooke. J Phys Chem A 126:2716-2728 (2022). 		TMC-1
N(X) < 1x1012 cm-2
various lines
2022 c-C2H4S
thiirane
A Search for Heterocycles in GOTHAM Observations of TMC-1
T. J. Barnum, M. A. Siebert, K. L. K. Lee, R. A. Loomis, P. B. Changala, S. B. Charnley, M. L. Sita, C. Xue, A. J. Remijan, A. M. Burkhardt, B. A. McGuire, and I. R. Cooke. J Phys Chem A 126:2716-2728 (2022). 		TMC-1
N(X) < 2x1012 cm-2
various lines
2022 c-C4H5N
1H-pyrrole

ASTROMOLECULE OF THE MONTH FOR MAR 2023 		A Search for Heterocycles in GOTHAM Observations of TMC-1
T. J. Barnum, M. A. Siebert, K. L. K. Lee, R. A. Loomis, P. B. Changala, S. B. Charnley, M. L. Sita, C. Xue, A. J. Remijan, A. M. Burkhardt, B. A. McGuire, and I. R. Cooke. J Phys Chem A 126:2716-2728 (2022).
Search for interstellar pyrrole and furan
M. L. Kutner, D. E. Machnik, J. D. Tucker, and R. L. Dickman. ApJ 242:541-544 (1980)
A search for interstellar pyrrole: Evidence that rings are less abundant than chains
P. C. Myers, P. Thaddeus, and R. A. Linke. ApJ 241:155-157 (1980) 		TMC-1
N(X) < 1x1012 cm-2
various lines
TMC-1
N(X) < 1012 cm-2
6 lines
Sgr B2
N(X) < 1-10 x 1013 cm-2
3 lines
2022 c-C4H4S
thiophene
A Search for Heterocycles in GOTHAM Observations of TMC-1
T. J. Barnum, M. A. Siebert, K. L. K. Lee, R. A. Loomis, P. B. Changala, S. B. Charnley, M. L. Sita, C. Xue, A. J. Remijan, A. M. Burkhardt, B. A. McGuire, and I. R. Cooke. J Phys Chem A 126:2716-2728 (2022). 		TMC-1
N(X) < 1x1013 cm-2
various lines
2022 c-C4H4O
furan

ASTROMOLECULE OF THE MONTH FOR AUG 2015 		A Search for Heterocycles in GOTHAM Observations of TMC-1
T. J. Barnum, M. A. Siebert, K. L. K. Lee, R. A. Loomis, P. B. Changala, S. B. Charnley, M. L. Sita, C. Xue, A. J. Remijan, A. M. Burkhardt, B. A. McGuire, and I. R. Cooke. J Phys Chem A 126:2716-2728 (2022).
Searches for new interstellar molecules, including a tentative detection of aziridine and a possible detection of propenal
J. E. Dickens, W. M. Irvine, A. Nummelin, H. Møllendal, S. Saito, S. Thorwirth, and Å Hjalmarson. Spectrochimica Acta A 57:643-660 (2001)
Search for interstellar pyrrole and furan
M. L. Kutner, D. E. Machnik, J. D. Tucker, and R. L. Dickman. ApJ 242:541-544 (1980)
Search for interstellar furan and imidazole
R. L. Dezafra, P. Thaddeus, M. Kutner, N. Scoville, P. M. Solomon, H. Weaver, and D. R. W. Williams. Astrophys Lett 10:1-3 (1972) 		TMC-1
N(X) < 9x1012 cm-2
various lines
Various Sources
N(X) < 1014 cm-2
6 lines
2022 c-C3H4N2
1H-imidazole

ASTROMOLECULE OF THE MONTH FOR APR 2019 		A Search for Heterocycles in GOTHAM Observations of TMC-1
T. J. Barnum, M. A. Siebert, K. L. K. Lee, R. A. Loomis, P. B. Changala, S. B. Charnley, M. L. Sita, C. Xue, A. J. Remijan, A. M. Burkhardt, B. A. McGuire, and I. R. Cooke. J Phys Chem A 126:2716-2728 (2022).
Searches for interstellar imidazole and cyanoform
W. M. Irvine, J. Ellder, Å. Hjalmarson, E. Kollberg, O. E. H. Rydbeck, G. O. Sørensen, B. Bak, and H. Svanholt. A&A 97:192-194 (1981)
Search for interstellar furan and imidazole
R. L. Dezafra, P. Thaddeus, M. Kutner, N. Scoville, P. M. Solomon, H. Weaver, and D. R. W. Williams. Astrophys Lett 10:1-3 (1972) 		TMC-1
N(X) < 1x1012 cm-2
various lines
TMC-1, Ori A, etc.
N < 0.6-100 x 1013 cm-2
303 → 202 (33412.2 MHz)
Sgr A, Sgr B2
110-111 (4602.30 MHz)
2022 c-C3H3NS
thiazole
A Search for Heterocycles in GOTHAM Observations of TMC-1
T. J. Barnum, M. A. Siebert, K. L. K. Lee, R. A. Loomis, P. B. Changala, S. B. Charnley, M. L. Sita, C. Xue, A. J. Remijan, A. M. Burkhardt, B. A. McGuire, and I. R. Cooke. J Phys Chem A 126:2716-2728 (2022). 		TMC-1
N(X) < 7x1012 cm-2
various lines
2022 c-C5H5N
pyridine
A Search for Heterocycles in GOTHAM Observations of TMC-1
T. J. Barnum, M. A. Siebert, K. L. K. Lee, R. A. Loomis, P. B. Changala, S. B. Charnley, M. L. Sita, C. Xue, A. J. Remijan, A. M. Burkhardt, B. A. McGuire, and I. R. Cooke. J Phys Chem A 126:2716-2728 (2022).
Astronomical searches for nitrogen heterocycles
S. B. Charnley, Y.-J. Kuan, H.-C. Huang, O. Botta, H. M. Butner, N. Cox, D. Despois, P. Ehrenfreund, Z. Kisiel, Y.-Y. Lee, A. J. Markwick, Z. Peeters, and S. D. Rodgers. Adv Space Res 36:137-145 (2005)
Search for Interstellar Acrylonitrile, Pyrimidine, and Pyridine
M. N. Simon and M. Simon. ApJ 184:757-761 (1973)
A search for interstellar molecular lines in the frequency range 8.6 to 9.2 GHz
R. A. Batchelor, J. W. Brooks, P. D. Godfrey, and R. D. Brown. Aus J Phys 26:557-560 (1973) 		TMC-1
N(X) < 2x1012 cm-2
various lines
IRC +10216, CRL 618
N(X): various, < 1012 cm-2
8 doubtlets, a-type, J < 25
Orion, Sgr B2
707-608 (44.390 GHz)
Orion A, Sgr B2, Sgr(NH3)A
101-000 F(1-1) (8.76284 GHz)
101-000 F(2-1) (8.76429 GHz)
101-000 F(0-1) (8.76648 GHz)
2022 c-C4H4N2
pyridazine
(1,2-diazine)
A Search for Heterocycles in GOTHAM Observations of TMC-1
T. J. Barnum, M. A. Siebert, K. L. K. Lee, R. A. Loomis, P. B. Changala, S. B. Charnley, M. L. Sita, C. Xue, A. J. Remijan, A. M. Burkhardt, B. A. McGuire, and I. R. Cooke. J Phys Chem A 126:2716-2728 (2022). 		TMC-1
N(X) < 2x1012 cm-2
various lines
2022 c-C4H4N2
pyrimidine
(1,3-diazine)

ASTROMOLECULE OF THE MONTH FOR AUG 2014 		A Search for Heterocycles in GOTHAM Observations of TMC-1
T. J. Barnum, M. A. Siebert, K. L. K. Lee, R. A. Loomis, P. B. Changala, S. B. Charnley, M. L. Sita, C. Xue, A. J. Remijan, A. M. Burkhardt, B. A. McGuire, and I. R. Cooke. J Phys Chem A 126:2716-2728 (2022). Deep K-band Observations of TMC-1 with the Green Bank Telescope: Detection of HC7O, Nondetection of HC11N, and a Search for New Organic Molecules
M. A. Cordiner, S. B. Charnley, Z. Kisiel, B. A. McGuire, and Y.-J. Kuan. ApJ 850:194 (2017)
Astronomical searches for nitrogen heterocycles
S. B. Charnley, Y.-J. Kuan, H.-C. Huang, O. Botta, H. M. Butner, N. Cox, D. Despois, P. Ehrenfreund, Z. Kisiel, Y.-Y. Lee, A. J. Markwick, Z. Peeters, and S. D. Rodgers. Adv Space Res 36:137-145 (2005)
A search for interstellar pyrimidine
Y.-J. Kuan, C.-H. Yan, S. B. Charnley, Z. Kisiel, P. Ehrenfreund, and H.-C. Huang. MNRAS 345:650-565 (2003)
Search for interstellar acrylonitrile, pyrimidine, and pyridine
M. N. Simon and M. Simon. ApJ 184:757-761 (1973)
 TMC-1
N(X) < 4x1012 cm-2
various lines
TMC-1
N(X) < 4.2 x 1010 cm-2
41,3-40,4 (19785.41 MHz)
CRL 618, IRC +10216
2 lines
Sgr B2(N), Orion KL, W51 e1/e2
N(X) < 1-3 x 1014 cm-2
many possible lines
Orion, Sgr B2
707-618 (46.266 GHz)
2022 c2-C8H7N
1H-indole
A Search for Heterocycles in GOTHAM Observations of TMC-1
T. J. Barnum, M. A. Siebert, K. L. K. Lee, R. A. Loomis, P. B. Changala, S. B. Charnley, M. L. Sita, C. Xue, A. J. Remijan, A. M. Burkhardt, B. A. McGuire, and I. R. Cooke. J Phys Chem A 126:2716-2728 (2022). 		TMC-1
N(X) < 4x1011 cm-2
various lines
2022 c2-C8H6S
benzo[b]thiophene
A Search for Heterocycles in GOTHAM Observations of TMC-1
T. J. Barnum, M. A. Siebert, K. L. K. Lee, R. A. Loomis, P. B. Changala, S. B. Charnley, M. L. Sita, C. Xue, A. J. Remijan, A. M. Burkhardt, B. A. McGuire, and I. R. Cooke. J Phys Chem A 126:2716-2728 (2022). 		TMC-1
N(X) < 1x1013 cm-2
various lines
2022 c2-C8H6O
benzofuran
A Search for Heterocycles in GOTHAM Observations of TMC-1
T. J. Barnum, M. A. Siebert, K. L. K. Lee, R. A. Loomis, P. B. Changala, S. B. Charnley, M. L. Sita, C. Xue, A. J. Remijan, A. M. Burkhardt, B. A. McGuire, and I. R. Cooke. J Phys Chem A 126:2716-2728 (2022). 		TMC-1
N(X) < 1x1012 cm-2
various lines
2022 c2-C9H7N
quinoline

ASTROMOLECULE OF THE MONTH FOR MAY 2018 		A Search for Heterocycles in GOTHAM Observations of TMC-1
T. J. Barnum, M. A. Siebert, K. L. K. Lee, R. A. Loomis, P. B. Changala, S. B. Charnley, M. L. Sita, C. Xue, A. J. Remijan, A. M. Burkhardt, B. A. McGuire, and I. R. Cooke. J Phys Chem A 126:2716-2728 (2022).
Deep K-band Observations of TMC-1 with the Green Bank Telescope: Detection of HC7O, Nondetection of HC11N, and a Search for New Organic Molecules
M. A. Cordiner, S. B. Charnley, Z. Kisiel, B. A. McGuire, and Y.-J. Kuan. ApJ 850:194 (2017)
Astronomical searches for nitrogen heterocycles
S. B. Charnley, Y.-J. Kuan, H.-C. Huang, O. Botta, H. M. Butner, N. Cox, D. Despois, P. Ehrenfreund, Z. Kisiel, Y.-Y. Lee, A. J. Markwick, Z. Peeters, and S. D. Rodgers. Adv Space Res 36:137-145 (2005) 		TMC-1
N(X) < 2x1012 cm-2
various lines
TMC-1
N(X) < 6.2 x 1011 cm-2
3 lines near 18993 MHz
IRC +10216, CRL 618, CRL 2688
N(X): < ~1013 cm-2
various b-type doublets
2022 c2-C8H6N2
quinoxaline
(1,4-benzodiazine)
A Search for Heterocycles in GOTHAM Observations of TMC-1
T. J. Barnum, M. A. Siebert, K. L. K. Lee, R. A. Loomis, P. B. Changala, S. B. Charnley, M. L. Sita, C. Xue, A. J. Remijan, A. M. Burkhardt, B. A. McGuire, and I. R. Cooke. J Phys Chem A 126:2716-2728 (2022). 		TMC-1
N(X) < 1x1013 cm-2
various lines
2022 c2-C8H6N2
quinozoline
(1,3-benzodiazine)
A Search for Heterocycles in GOTHAM Observations of TMC-1
T. J. Barnum, M. A. Siebert, K. L. K. Lee, R. A. Loomis, P. B. Changala, S. B. Charnley, M. L. Sita, C. Xue, A. J. Remijan, A. M. Burkhardt, B. A. McGuire, and I. R. Cooke. J Phys Chem A 126:2716-2728 (2022). 		TMC-1
N(X) < 4x1010 cm-2
various lines
2022 c2-C8H6N2
phthalazine
(2,3-benzodiazine)
A Search for Heterocycles in GOTHAM Observations of TMC-1
T. J. Barnum, M. A. Siebert, K. L. K. Lee, R. A. Loomis, P. B. Changala, S. B. Charnley, M. L. Sita, C. Xue, A. J. Remijan, A. M. Burkhardt, B. A. McGuire, and I. R. Cooke. J Phys Chem A 126:2716-2728 (2022). 		TMC-1
N(X) < 9x1010 cm-2
various lines
2022 NH2CH2CH2SH
cysteamine
(5 conformers)
Micro- and millimeter-wave spectra of five conformers of cysteamine and their interstellar search
W. Song, A. Maris, V. M. Rivilla, F. Fortuna, L. Evangelisti, D. Lv, L. Rodríguez-Almeida, I. Jiménez-Serra, J. Martín-Pintado, and S. Melandri. A&A 661:A129 (2022). 		G+0.693-0.027
[X]/[H2] < (0.2-1.3)x10-10
various lines
2022 CH3OCH2COCH3
methoxyacetone
Laboratory Measurements and Astronomical Search for Methoxyacetone and Methyl Methoxyacetate
J. Lei, M. Li, C. Duan, J. Li, D. Quan, J. Wang, J. Li, J. Chen, X. Xu, F. Zhu, L. Yu, and Q. Gou. J Phys Chem A 126:3549-3554 (2022). 		Sgr B2(N)
N(X) < 4.2x1013 cm-2 at 12 K
404-303 (14807.33 MHz
725-716 (15576.19 MHz)
2022 CH3OCH2COOCH3
methyl methoxyacetate
Laboratory Measurements and Astronomical Search for Methoxyacetone and Methyl Methoxyacetate
J. Lei, M. Li, C. Duan, J. Li, D. Quan, J. Wang, J. Li, J. Chen, X. Xu, F. Zhu, L. Yu, and Q. Gou. J Phys Chem A 126:3549-3554 (2022). 		Sgr B2(N)
N(X) < 2.9x1013 cm-2 at 12 K
605-505 (16540.25 MHz)
624-523 (16709.30 MHz)
2022 E-CH3CHCHCCH
E-3-penten-1-yne
Discovery of five cyano derivatives of propene with the QUIJOTE line survey
J. Cernicharo, R. Fuentetaja, C. Cabezas, M. Agúndez, N. Marcelino, B. Tercero, J. R. Pardo, and P. de Vicente. A&A 663:L5 (2022). 		TMC-1
N(X) < 5x1011 cm-2
various lines
2022 Z-CH3CHCHCCH
Z-3-penten-1-yne
Discovery of five cyano derivatives of propene with the QUIJOTE line survey
J. Cernicharo, R. Fuentetaja, C. Cabezas, M. Agúndez, N. Marcelino, B. Tercero, J. R. Pardo, and P. de Vicente. A&A 663:L5 (2022). 		TMC-1
N(X) < 9x1011 cm-2
various lines
2022 1-CH3CH2CHNH
1-propanimine
Submillimeter wave spectroscopy and astronomical search for 1-propanimine
L. Margulès, A. Remijan, A. Belloche, R. A. Motiyenko, B. A. McGuire, C. Xue, H. S. P. Müller, R. T. Garrod, K. M. Menten, and J.-C. Guillemin. A&A 663:A132 (2022). 		Sgr B2(N), etc.
N(X) < ~1017 cm-2
various lines
2022 HCOCH2CN
cyanoacetaldehyde
Molecular Precursors of the RNA-World in Space: New Nitriles in the G+0.693-0.027 Molecular Cloud
V. M. Rivilla, I. Jiménez-Serra, J. Martín-Pintado, L. Colzi, B. Tercero, P. de Vicente, S. Zeng, S. Martín, J. García de la Concepción, L. Bizzocchi, M. Melosso, F. Rico-Villas, and M. A. Requena-Torres. Front Astron Space Sci 9:876870 (2022). 		G+0.693-0.027
[X]/[H2] < 2.7x10-10
various lines
2022 HCOC(OH)CH2
2-hydroxyprop-2-enal
Millimetre-wave spectroscopy of 2-hydroxyprop-2-enal and an astronomical search with ALMA
J. Koucký, L. Kolesniková, K. Luková, K. Vávra, P. Kania, A. Coutens, J.-C. Loison, J. K. Jørgensen, A. Belloche, and Š. Urban. A&A 666:A158 (2022). 		IRAS 16293-2422
N(X) < 9.4x1014 cm-2
 Sgr B2(N1)
N(X) < 7.2x1016 cm-2
multiple transitions
2022 C2H3NCO
vinyl isocyanate
Millimeter wave spectrum and search for vinyl isocyanate toward Sgr B2(N) with ALMA
K. Vávra, L. Kolesniková, A. Belloche, R. T. Garrod, J. Koucký, T. Uhlíková, K. Luková, J.-C. Guillemin, P. Kania, H. S. P. Müller, K. M. Menten, and Š. Urban. A&A 666:A50 (2022). 		Sgr B2(N)
N(cis) < 5.0x1017 cm-2
 N(trans) < 2.4x1016 cm-2
various transitions
2022 n-C3H7HCO
n-butanal

Toward the limits of complexity of interstellar chemistry: Rotational spectroscopy and astronomical search for n- and i-butanal
M. Sanz-Novo, A. Belloche, V. M. Rivilla, R. T. Garrod, J. L. Alonso, P. Redondo, C. Barrientos, L. Kolesniková, J. C. Valle, L. Rodríguez-Almeida, I. Jimenez-Serra, J. Martín-Pintado, H. S. P. Müller, and K. M. Menten. A&A 666:A114 (2022). 		Sgr B2(N),G+0.693-0.027
several conformers,
many transitions
2022 i-C3H7HCO
i-butanal
Toward the limits of complexity of interstellar chemistry: Rotational spectroscopy and astronomical search for n- and i-butanal
M. Sanz-Novo, A. Belloche, V. M. Rivilla, R. T. Garrod, J. L. Alonso, P. Redondo, C. Barrientos, L. Kolesniková, J. C. Valle, L. Rodríguez-Almeida, I. Jimenez-Serra, J. Martín-Pintado, H. S. P. Müller, and K. M. Menten. A&A 666:A114 (2022). 		Sgr B2(N),G+0.693-0.027
two conformers,
many transitions
2022 C4
tetracarbon
Presumed Detection of C5 Molecule in the Interstellar Medium
J. Krełowski, R. Hakalla, and W. Szajna. ApJ 939:113 (2022). 		HD 166734, HD 80077
electronic transition at 3789 Å
2023 C12H8
1-ethynylnaphthalene

Laboratory rotational spectroscopy and astronomical search of ethynyl substituted naphthalene
C. Cabezas, I. Peña, and J. Cernicharo. MNRAS 519:2590 (2023). 		TMC-1
N(X) < 1.0x1013 cm-2
various transitions
2023 C12H8
2-ethynylnaphthalene

Laboratory rotational spectroscopy and astronomical search of ethynyl substituted naphthalene
C. Cabezas, I. Peña, and J. Cernicharo. MNRAS 519:2590 (2023). 		TMC-1
N(X) < 6.8x1012 cm-2
various transitions
2023 (CH3)2C=NH
2-propanimine

Millimeter-wave spectrum of 2-propanimine
L. Zou, J.-C. Guillemin, A. Belloche, J. K. Jørgensen, L. Margulès, R. A Motiyenko, and P. Groner. MNRAS 520:4089-4102 (2023). 		Sgr B2(N1S)
[X]/[CH2NH] < 1/18
 IRAS 16293-2422
[X]/[CH2NH] < 50-83%
various transitions
2023 H2NCHCHCN
aminoacrylonitrile
A High-resolution Spectroscopic Analysis of Aminoacrylonitrile and an Interstellar Search toward G+0.693
D. Alberton, V. Lattanzi, C. Endres, V. M. Rivilla, J. C. Guillemin, P. Caselli, I. Jiménez-Serra, and J. Martín-Pintado. ApJ 951:108 (2023). 		G+0.693-0.027
[X]/[H2] < 4.9x10-11
70,7-60,6 (43896.76 MHz)
60,6-50,5 (38099.96 MHz)
71,7-61,6 (42941.29 MHz)
2023 C4H8O2
acetoin

Laboratory Rotational Spectrum and Radio-Astronomical Search of Acetoin
C. Duan, Y. Zheng, W. Cheng, J. Lei, J. Li, D. Quan, J. Wang, J. Chen, J. Li, X. Xu, and Q. Gou. J Phys Chem A 127:5772-5778 (2023). 		Sgr B2(N)
N(X) < 1011 cm-2
various lines
2023 CH3NHCH3
dimethylamine

Rotation-tunnelling spectrum and astrochemical modelling of dimethylamine, CH3NHCH3, and searches for it in space
H. S. P. Müller, R. T. Garrod, A. Belloche, V. M. Rivilla, K. M. Menten, I. Jiménez-Serra, J Martín-Pintado, F. Lewen, and S. Schlemmer. MNRAS 523:2887-2917 (2023). 		Sgr B2(N1S)
N(X) < N[CH3NH2] / 14
 Sgr B2(N2b)
N(X) < N[CH3NH2] / 4.5
 G+0693-0.027
N(X) < N[CH3NH2] / 39
various transitions with
hyperfine structure
2023 CH3OC(O)NH2
syn-methyl carbamate
First Glycine Isomer Detected in the Interstellar Medium: Glycolamide (NH2C(O)CH2OH)
V. M. Rivilla, M. Sanz-Novo, I. Jiménez-Serra, J. Martín-Pintado, L. Colzi, S. Zeng, A. Megías, Á. López-Gallifa, A. Martínez-Henares, S. Massalkhi, B. Tercero, P. de Vicente, S. Martín, D. San Andrés, M. A. Requena-Torres, and J. L. Alonso. ApJL 953:L20 (2023) 		G+0.693-0.027
[X]/[H2] < 2.5x10-10
5 lines (w/hyperfine struct)
near 36.72 GHz
2023 NH2C(O)CH2OH
anti-glycolamide
First Glycine Isomer Detected in the Interstellar Medium: Glycolamide (NH2C(O)CH2OH)
V. M. Rivilla, M. Sanz-Novo, I. Jiménez-Serra, J. Martín-Pintado, L. Colzi, S. Zeng, A. Megías, Á. López-Gallifa, A. Martínez-Henares, S. Massalkhi, B. Tercero, P. de Vicente, S. Martín, D. San Andrés, M. A. Requena-Torres, and J. L. Alonso. ApJL 953:L20 (2023) 		G+0.693-0.027
[X]/[H2] < 0.13x10-10
2 lines (w/hyperfine struct)
near 32.92 GHz
2023 CH3CONHOH
acetohydroxamic acid
Laboratory detection and astronomical study of interstellar acetohydroxamic acid, a glycine isomer
M. Sanz-Novo, J. L. Alonso, V. M. Rivilla, B. A. McGuire, I. León, S. Mata, I. Jimenez-Serra, and J. Martín-Pintado. A&A 666:A134 (2022)
First Glycine Isomer Detected in the Interstellar Medium: Glycolamide (NH2C(O)CH2OH)
V. M. Rivilla, M. Sanz-Novo, I. Jiménez-Serra, J. Martín-Pintado, L. Colzi, S. Zeng, A. Megías, Á. López-Gallifa, A. Martínez-Henares, S. Massalkhi, B. Tercero, P. de Vicente, S. Martín, D. San Andrés, M. A. Requena-Torres, and J. L. Alonso. ApJL 953:L20 (2023) 		TMC-1
[X]/[H2] < 1x10-9
 G+0.6933-0.037
[X]/[H2] < 2x10-10
various transitions
G+0.6933-0.037
[X]/[H2] < 1.7x10-10
one transition near 20.83 GHz
2023 C5H6
E-3-penten-1-yne

Rotational spectra and astronomical search of five ethynyl derivatives of propene
C. Cabezas, M. Agúndez, Y.-T. Liu, Y. Endo, and J. Cernicharo. MNRAS 524:491-497 (2023). 		TMC-1
N(X) < 2.6x1011 cm-2
various lines
2023 C5H6
Z-3-penten-1-yne

Rotational spectra and astronomical search of five ethynyl derivatives of propene
C. Cabezas, M. Agúndez, Y.-T. Liu, Y. Endo, and J. Cernicharo. MNRAS 524:491-497 (2023). 		TMC-1
N(X) < 6.4x1011 cm-2
various lines
2023 C5H6
Isopropenylacetylene

Rotational spectra and astronomical search of five ethynyl derivatives of propene
C. Cabezas, M. Agúndez, Y.-T. Liu, Y. Endo, and J. Cernicharo. MNRAS 524:491-497 (2023). 		TMC-1
N(X) < 2.2x1012 cm-2
various lines
2023 C5H6
gauche-1-penten-4-yne
Rotational spectra and astronomical search of five ethynyl derivatives of propene
C. Cabezas, M. Agúndez, Y.-T. Liu, Y. Endo, and J. Cernicharo. MNRAS 524:491-497 (2023). 		TMC-1
N(X) < 1.2x1012 cm-2
various lines
2023 C5H6
cis-1-penten-4-yne
Rotational spectra and astronomical search of five ethynyl derivatives of propene
C. Cabezas, M. Agúndez, Y.-T. Liu, Y. Endo, and J. Cernicharo. MNRAS 524:491-497 (2023). 		TMC-1
N(X) < 2.0x1012 cm-2
various lines
2023 DOCH2CN
2-hydroxyacetonitrile

Rotational spectroscopy and astronomical search for the 2-hydroxyacetonitrile isotopologues HO13CH2CN, HOCH213CN, and DOCH2CN
L. Margulès, A. Coutens, N. F. W. Ligterink, A. Ahmadi, R. A. Motiyenko, E. A. Alekseev, C. Vastel, E. Caux, and J.-C. Guillemin. MNRAS 524:1211-1218 (2023). 		SMMM1-a
N(X) < 1x1014 cm-2
various lines
2023 HOCH213CN
2-hydroxyacetonitrile

Rotational spectroscopy and astronomical search for the 2-hydroxyacetonitrile isotopologues HO13CH2CN, HOCH213CN, and DOCH2CN
L. Margulès, A. Coutens, N. F. W. Ligterink, A. Ahmadi, R. A. Motiyenko, E. A. Alekseev, C. Vastel, E. Caux, and J.-C. Guillemin. MNRAS 524:1211-1218 (2023). 		SMMM1-a
N(X) < 2x10X cm-2
various lines
2023 HO13CH2CN
2-hydroxyacetonitrile

Rotational spectroscopy and astronomical search for the 2-hydroxyacetonitrile isotopologues HO13CH2CN, HOCH213CN, and DOCH2CN
L. Margulès, A. Coutens, N. F. W. Ligterink, A. Ahmadi, R. A. Motiyenko, E. A. Alekseev, C. Vastel, E. Caux, and J.-C. Guillemin. MNRAS 524:1211-1218 (2023). 		SMMM1-a
N(X) < 2x1014 cm-2
various lines
2023 C6H4(CCH)2
1,2-diethynylbenzene

Detection of ethynylbenzene in TMC-1 and the interstellar search for 1,2-diethynylbenzene
D. Loru, C. Cabezas, J. Cernicharo, M. Schnell, and A. L. Steber. A&A 677:A166 (2023). 		TMC-1
N(X) < 2x1012 cm-2
various lines
2023 CD3OD
D4-methanol

Investigation of the rotational spectrum of CD3OD and an astronomical search toward IRAS 16293-2422
V. V. Ilyushin, H. S. P. Müller, J. K. Jørgensen, S. Bauerecker, C. Maul, R. Porohovoi, E. A. Alekseev, O. Dorovskaya, F. Lewen, S. Schlemmer, and R. M. Lees. A&A 677:A49 (2023). 		IRAS 16293-2422
16 transitions, partial matches
2023 c2-C7H8
norbornadiene


ASTROMOLECULE OF THE MONTH FOR NOV 2024 		Searches for bridged bicyclic molecules in space-norbornadiene and its cyano derivatives
M.-A. Martin-Drumel, J.-T. Spaniol, H. Hölzel, M. Agúndez, J. Cernicharo, K. Moth-Poulsen, and U. Jacovella. Faraday Discuss 245;284-297 (2013). 		TMC-1
N(X) < 1.6x1014 cm-2
various lines
2023 c2-C7H7CN
cyano-norbornadiene

Searches for bridged bicyclic molecules in space-norbornadiene and its cyano derivatives
M.-A. Martin-Drumel, J.-T. Spaniol, H. Hölzel, M. Agúndez, J. Cernicharo, K. Moth-Poulsen, and U. Jacovella. Faraday Discuss 245;284-297 (2013). 		TMC-1
N(X) < 4.9x1010 cm-2
various lines
2023 c2-C7H6(CN)2
dicyano-norbornadiene
Searches for bridged bicyclic molecules in space-norbornadiene and its cyano derivatives
M.-A. Martin-Drumel, J.-T. Spaniol, H. Hölzel, M. Agúndez, J. Cernicharo, K. Moth-Poulsen, and U. Jacovella. Faraday Discuss 245;284-297 (2013). 		TMC-1
N(X) < 2.9x1010 cm-2
various lines
2023 NH2CH2COOH
glycine


ASTROMOLECULE OF THE MONTH FOR SEP 2003 		A rigorous attempt to verify interstellar glycine
L. E. Snyder, F. J. Lovas, J. M. Hollis, D. N. Friedel, P. R. Jewell, A. Remijan, V. V. Ilyushin, E. A. Alekseev, and S. F. Dyubko. ApJ 619:914-930 (2005)
A search for biomolecules in Sagittarius B2 (LMH) with the Australia Telescope Compact Array
P. A. Jones, M. R. Cunningham, P. D. Godfrey, and D. M. Cragg, MNRAS 374:579-589 (2007)
A search for propylene oxide and glycine in Sagittarius B2 (LMH) and Orion
M. R. Cunningham and 19 co-workers. MNRAS 376:1201-1210 (2007)
The Spatial Distribution of Complex Organic Molecules in the L1544 Pre-stellar Core
I. Jiménez-Serra, A. I. Vasyunin, P. Caselli, N. Marcelino, N. Billot, S. Viti, L. Testi, C. Vastel, B. Lefloch, and R. Bachiller. ApJ 830:L6 (2016).
Toward the RNA-World in the Interstellar Medium-Detection of Urea and Search of 2-Amino-oxazole and Simple Sugars
I. Jiménez-Serra, J. Martín-Pintado, V. M. Rivilla, L. Rodríguez-Almeida, E. R. Alonso Alonso, S. Zeng, E. J. Cocinero, S. Martín, M. Requena-Torres, R. Martín-Domenech, and L. Testi. Astrobio 20:1048-1066 (2020).
First Glycine Isomer Detected in the Interstellar Medium: Glycolamide (NH2C(O)CH2OH)
V. M. Rivilla, M. Sanz-Novo, I. Jiménez-Serra, J. Martín-Pintado, L. Colzi, S. Zeng, A. Megías, Á. López-Gallifa, A. Martínez-Henares, S. Massalkhi, B. Tercero, P. de Vicente, S. Martín, D. San Andrés, M. A. Requena-Torres, and J. L. Alonso. ApJL 953:L20 (2023)
Deep search for glycine conformers in Barnard 5
T. Carl, E. S. Wirström, P. Bergman, S. B. Charnley, Y.-L. Chuang, and Y.-J. Kuan. MNRAS 524:5993-6003 (2023)
Discomfirmed detection:
Interstellar glycine
Y.-J. Kuan, S. B. Charnley, H.-C. Huang, W.-L. Tseng, and Z. Kisiel. ApJ 593:848-867 (2003) 		Sgr B2(N-LMH), Orion KL,
W51 e1/e2
27 mm-wave lines
L1544
[X]/[H2] < 2x10-11
IRAS 16293-2422B
[X]/[H2] < 2.1x10-10
G+0.6933-0.037
[X]/[H2] < 1.7x10-10
various transitions
Barnard 5
[X]/[H2] < (2-5)x10-10, (0.7-3)x10-11
various lines
2024 C11H12N2O2
tryptophan

Interstellar tryptophan revisited
R. L Hudson. MNRAS 526:4051-4053 (2023).
On the Origin of Infrared Bands Attributed to Tryptophan in Spitzer Observations of IC 348
A. Dhariwal, T. H. Speak, L. Zeng, A. Rashidi, B. Moore, O. Berné, A. J. Remijan, I. Schroetter, B. A. McGuire, V. M. Rivilla, A. Belloche, J. K. Jørgensen, P. Djuricanin, T. Momose, and I. R. Cooke. ApJL 968:L9 (2024).
Discomfirmed detection:
A search for tryptophan in the gas of the IC 348 star cluster of the Perseus molecular cloud
S. Iglesias-Groth. MNRAS 523:2876-2886 (2023). 		IC 348
various IR transitions
2024 H2CNCCH
N-ethynylmethanimine
Laboratory detection and astronomical search of N-ethynylmethanimine, H2CNCCH
C. Cabezas, Y. Endo, V. M. Rivilla, M. Agúndez, I. Jiménez-Serra, J. Martín-Pintado, and J. Cernicharo. MNRAS 531:3151-3158 (2024). 		G+0.693-0.027
[X]/[H2] < 1.3x10-13
 L483
N(X) < 7.9x1011 cm-2
 TMC1
N(X) < 2.8x1011 cm-2
various lines, including
hyperfine components
2024 H2NCO
carbamoyl readical

Unveiling the gas phase H2NCO radical: Laboratory rotational spectroscopy and interstellar searches in the direction of IRAS 16293-2422
M.-A. Martin-Drumel, A. Coutens, J.-C. Loison, J. K. Jørgensen, and O. Pirali. A&A 687:A233 (2024). 		IRAS 16293-2422
[X]/[H2] < 10-9
various lines
2024 NCCS More sulphur in TMC-1: Discovery of the NC3S and HC3S radicals with the QUIJOTE line survey
J. Cernicharo, C. Cabezas, M. Agúndez, R. Fuentetaja, B. Tercero, N. Marcelino, and P. de Vicente. A&A 688:L13 (2024). 		TMC-1
N(X) < ~1011 cm-2
various lines
2024 HC5S More sulphur in TMC-1: Discovery of the NC3S and HC3S radicals with the QUIJOTE line survey
J. Cernicharo, C. Cabezas, M. Agúndez, R. Fuentetaja, B. Tercero, N. Marcelino, and P. de Vicente. A&A 688:L13 (2024). 		TMC-1
N(X) < ~1011 cm-2
various lines
2024 NC4S More sulphur in TMC-1: Discovery of the NC3S and HC3S radicals with the QUIJOTE line survey
J. Cernicharo, C. Cabezas, M. Agúndez, R. Fuentetaja, B. Tercero, N. Marcelino, and P. de Vicente. A&A 688:L13 (2024). 		TMC-1
N(X) < ~1011 cm-2
various lines
2024 NC5S More sulphur in TMC-1: Discovery of the NC3S and HC3S radicals with the QUIJOTE line survey
J. Cernicharo, C. Cabezas, M. Agúndez, R. Fuentetaja, B. Tercero, N. Marcelino, and P. de Vicente. A&A 688:L13 (2024). 		TMC-1
N(X) < ~1011 cm-2
various lines
2024 NC6S More sulphur in TMC-1: Discovery of the NC3S and HC3S radicals with the QUIJOTE line survey
J. Cernicharo, C. Cabezas, M. Agúndez, R. Fuentetaja, B. Tercero, N. Marcelino, and P. de Vicente. A&A 688:L13 (2024). 		TMC-1
N(X) < ~1011 cm-2
various lines
2024 NC7S More sulphur in TMC-1: Discovery of the NC3S and HC3S radicals with the QUIJOTE line survey
J. Cernicharo, C. Cabezas, M. Agúndez, R. Fuentetaja, B. Tercero, N. Marcelino, and P. de Vicente. A&A 688:L13 (2024). 		TMC-1
N(X) < ~1011 cm-2
various lines
2024 HCCSCN
ethynyl thiocyanate 		Synthesis and Spectroscopic Characterization of Interstellar Candidate Ethynyl Thiocyanate: HCCSCN
E. R. Alonso, A. Insausti, L. Kolesniková, I. León, B. A. McGuire, C. N. Shingledecker, M. Agúndez, J. Cernicharo, V. M. Rivilla, C. Cabezas, I. Jiménez-Serra, J. Martín-Pintado, and J.-C. Guillemin. ApJ 976:95 (2024). 		Sgr B2(N)
N(X) < 5 x 1015 cm-2
NGC 6334I
N(X) < 5 x 1015 cm-2
G+0.693-0.027
N(X) < 1.1 x 1012 cm-2
TMC-1
N(X) < 5 x 1010 cm-2
various transitions

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uv-vis (electronic)     mm/sub-mm (rotational)     infrared (vibrational)
Maintained by DE Woon
Updated 24 November 2024