Methanol was one of the earliest molecules to be detected by means of radio astronomy. A plethora of reports deserve mentioning here. Therefore, this documentation may well be incomplete for quite a while.
J. A. Ball, C. A. Gottlieb, A. E. Lilley, and H. E. Radford
gave an account of the
Detection of Methyl Alcohol in Sagittarius
Astrophys. J. 162, L203–L210 (1970).
They used the 140-foot Greenbank radio telescope for the 110 – 111 transition near 834 MHz to detect methanol in emission from Sagittarius (Sgr) A and B2.

C. A. Gottlieb, J. A. Ball, E. W. Gottlieb, and D. F. Dickinson
Interstellar Methyl Alcohol
Astrophys. J. 227, 422–432 (1979).
They used the 11 m Kitt Peak radio telescope to search for the J = 2 – 1 transitions of CH3OH, 13CH3OH, and CH3OD in the 3 mm region toward several galactic sources. CH3OH was detected toward 14 sources, at least the majority of these are hot-core sources. The identification of 13CH3OH lines toward Sgr B2 may well be correct (the 12C to 13C ratio of somewhat less than 10 is probably affected by opacity of the CH3OH lines), but the identification of CH3OD toward the same source is definitively incorrect; see for example:
A. Belloche, H. S. P. Müller, R. T. Garrod, and K. M. Menten
Exploring Molecular Complexity with ALMA (EMoCA): Deuterated Complex Organic Molecules in Sagittarius B2(N2)
Astron. Astrophys. 587, Art. No. A91 (2016).

F. F. Gardner, J. B. Whiteoak, J. Reynolds, W. L. Peters, and T. B. H. Kuiper
announced the
First Detection of the <sup>18</sup>O Isotope of Methanol
Mon. Not. R. Astron. Soc. 240, 35P–40P (1989).
The NASA's 70 m dish at Tidbinbilla was used to detect the JK = 20 − 3−1 transition of CH318OH near 11.6 GHz toward Sgr B2. The derived 16O to 18O ratio of 210 ± 40 is in line with other results obtained toward the galactic center.

R. Mauersberger, C. Henkel, T. Jacq, C. M. Walmsley
Deuterated Methanol in Orion
Astron. Astrophys. 194, L1−L4 (1988).
About one dozen transitions of CH3OD were detected with good signal-to-noise ratios toward Orion KL between 110 and 230 GHz using the IRAM 30 m telescope.

T. Jacq, C. M. Walmsley, R. Mauersberger, T. Anderson, E. Herbst, F. C. De Lucia
gave an account of the
Detection of interstellar CH<sub>2</sub>DOH
Astron. Astrophys. 271, 276–281 (1993).
The IRAM 30 m telescope was employed to detect six lines of CH2DOH toward Orion-IRc2 between 90 and 230 GHz. Several CH3OD transitions were observed newly around 136 GHz. The abundance of CH2DOH was estimated to be slightly higher (by up to 50 %) than that of CH3OD.

B. Parise, C. Ceccarelli, A. G. G. M. Tielens, E. Herbst, B. Lefloch, E. Caux, A. Castets, I. Mukhopadhyay, L. Pagani, and L. Loinard
announced the
Detection of Doubly-deuterated Methanol in the Solar-type Protostar IRAS 16293−2422
Astron. Astrophys. 393, L49–L53 (2002).
About a dozen lines of CHD2OH were detected between 89 and 224 GHz with very modest to good signal-to-noise ratios employing the IRAM 30 m telescope. The CH2DOH isotopolog has an abundance about five times higher. The comparisons to CH3OH are incorrect because of severe opacity of these lines.

In addition,
B. Parise, C. Ceccarelli, A. G. G. M. Tielens, A. Castets, E. Caux, B. Lefloch, and S. Maret
Testing Grain Surface Chemistry: a Survey of Deuterated Formaldehyde and Methanol in Low-mass Class 0 Protostars
Astron. Astrophys. 453, 949–958 (2006).
CHD2OH was also found toward the low-mass protostars IRAS 2, IRAS 4A, and IRAS 4B in the NGC 1333 molecular cloud.

B. Parise, A. Castets, E. Herbst, E. Caux, C. Ceccarelli, I. Mukhopadhyay, and A. G. G. M. Tielens
gave an account of the
First Detection of Triply-deuterated Methanol
Astron. Astrophys. 416, 159–163 (2004).
A dozen lines of CD3OH were detected around 158 GHz toward IRAS 16293−2422 with very modest to reasonable signal-to-noise ratios employing the IRAM 30 m telescope. The column density of CH3OH was derived from that of 13CH3OH. The CH3OH : CH2DOH : CHD2OH : CD3OH ratios were about 126 : 38 : 7.7 : 1.

F. J. Lovas, R. D. Suenram, L. E. Snyder, J. M. Hollis, and R. M. Lees
reported on the
Detection of the Torsionally Excited State of Methanol in Orion A
Astrophys. J. 253, 149–153 (1982).
Three lines partaining to four transitions of torsionally excited methanol were detected with the 11 m Kitt Peak radio telescope at 3 mm.

V. V. Ilyushin, H. S. P. Müller, J. K. Jørgensen, S. Bauerecker, C. Maul, Y. Bakhmat, E. A. Alekseev, O. Dorovskaya, S. Vlasenko, F. Lewen, S. Schlemmer, K. Berezkin, and R. M. Lees
investigated the
Rotational and Rovibrational Spectroscopy of CD<sub>3</sub>OH with an Account of CD<sub>3</sub>OH toward IRAS 16293−2422
Astron. Astrophys. 658, Art. No. A127 (2022).
Using the Protostellar Interferometric Line Survey carried out with ALMA, several lines of torsionally excited CD3OH were detected between 329 and 363 GHz; nine unblended or only slightly blended lines of this vibrationally excited state were shown in a figure around 350.6 GHz. The rotational temperature was ~225 K, and the CH3OH to CD3OH ratio was about 300. Lines of torsionally excited deuterated methanol will be more prominent for 12C isotopologs containing fewer D atoms.

Contributor(s): H. S. P. Müller; 04, 2022

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