Handbook of Frequency Allocations and Spectrum Protection for Scientific Uses: Second Edition (2015)

Chapter: Appendix D: International Astronomical Union Spectral Lines of Most Importance Between 300 and 1000 GHz

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Suggested Citation: "Appendix D: International Astronomical Union Spectral Lines of Most Importance Between 300 and 1000 GHz." National Academies of Sciences, Engineering, and Medicine. 2015. Handbook of Frequency Allocations and Spectrum Protection for Scientific Uses: Second Edition. Washington, DC: The National Academies Press. doi: 10.17226/21774.
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D

International Astronomical Union Spectral Lines of Most Importance Between 300 and 1000 GHz

At each triennial meeting of the General Assembly, the International Astronomical Union (IAU) carefully reviews the list of astrophysically most important spectral lines that it maintains. The IAU expresses the need to protect these frequency bands from in-band, band-edge, and harmonic emissions, especially from spaceborne transmitters.

In preparation for World Radiocommunication Conference 2000, which revised the allocations above 71 GHz, a millimeter-wavelength working group of the Scientific Committee on Frequency Allocations for Radio Astronomy and Space Science (IUCAF) examined all then-known transitions in the millimeter and submillimeter wavebands. The working group selected a limited number of the astrophysically most important spectral lines to supplement the earlier lists, such as those produced by the IAU, to be used in allocating frequency bands to the Radio Astronomy Service. Spectral lines between 300-1000 GHz are listed in Table D.1. Unless otherwise noted, the band limits are Doppler-shifted frequencies corresponding to radial velocities of ±300 km/s, consistent with line radiation occurring in our Milky Way galaxy. Although no formal frequency allocations are established above 275 GHz, the International Telecommunication Union (ITU) Radio Regulation 5.565 urges administrations to take all practicable steps to protect passive services from harmful interference in the frequency range of 275-1000 GHz. Of particular note are the following frequency bands, which are identified for passive use by the Radio Astronomy Service: 275-323 GHz, 327-371 GHz, 388-424 GHz, 426-442 GHz, 453510 GHz, 623-711 GHz, 795-909 GHz, and 926-945 GHz. These frequency bands correspond to atmospheric “windows” (see Figure 2.6) that permit ground-based observations of cosmic sources from high, dry sites.

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Suggested Citation: "Appendix D: International Astronomical Union Spectral Lines of Most Importance Between 300 and 1000 GHz." National Academies of Sciences, Engineering, and Medicine. 2015. Handbook of Frequency Allocations and Spectrum Protection for Scientific Uses: Second Edition. Washington, DC: The National Academies Press. doi: 10.17226/21774.
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TABLE D.1 The Most Important Spectral Lines Between 300 and 1000 GHz

Species Formula Frequency (GHz) Suggested Minimum Band (GHz) Notes1
Hydronium H3O+ 307.192 306.88-307.50  
Deuterated water HDO 313.750 313.44-314.06  
Carbon monoxide C18O 329.330 329.00-329.66  
Carbon monoxide 13CO 330.587 329.49-330.92  
Carbon monosulphide CS 342.883 341.74-343.23  
Carbon Monoxide CO 345.796 345.45-346.14  
Hydrogen cyanide HCN 354.484 353.30-354.84  
Formylium HCO+ 356.734 355.54-357.09  
Oxygen O2 368.498 368.13-368.87  
Diazenylium N2H+ 372.672 372.30-373.04 2
Water vapor H2O 380.197 379.82-380.58 2
Hydronium H3O+ 388.459 388.07-388.85  
Carbon monosulphide CS 391.847 390.54-392.24  
Oxygen O2 424.763 424.34-425.19  
Carbon monoxide C18O 439.088 438.65-439.53  
Carbon monoxide 13CO 440.765 439.30-441.21  
Carbon monoxide CO 461.041 459.50-461.50  
Deuterated water HDO 464.925 464.46-465.39  
Carbon CI 492.162 490.52-492.65  
Deuterated water HDO 509.292 508.78-509.80  
Hydrogen cyanide HCN 531.716 529.94-532.25 2
Carbon monosulphide CS 538.689 536.89-539.23 2
Water vapor H218O 547.676 547.13-548.22 2
Carbon monoxide 13CO 550.926 549.09-551.48 2
Water vapor H2O 556.936 556.38-557.49 2
Ammonia 15NH3 572.113 571.54-572.69 2
Ammonia NH3 572.498 571.93-573.07 2
Carbon monoxide CO 576.268 574.35-576.84 2
Carbon monosulphide CS 587.616 587.03-588.20 2
Deuterated water HDO 599.927 599.33-600.53 2
Water vapor H2O 620.700 620.08-621.32 2
Hydrogen chloride HCl 625.040 624.41-625.67  
Hydrogen chloride HCl 625.980 625.35-626.61  
Carbon monosulphide CS 636.532 634.41-637.17  
Carbon monoxide 13CO 661.067 658.86-661.73  
Carbon monoxide CO 691.473 689.17-692.16  
Page 243 Cite
Suggested Citation: "Appendix D: International Astronomical Union Spectral Lines of Most Importance Between 300 and 1000 GHz." National Academies of Sciences, Engineering, and Medicine. 2015. Handbook of Frequency Allocations and Spectrum Protection for Scientific Uses: Second Edition. Washington, DC: The National Academies Press. doi: 10.17226/21774.
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Species Formula Frequency (GHz) Suggested Minimum Band (GHz) Notes1
Oxygen O2 715.393 714.68-716.11 2
Carbon monosulphide CS 734.324 733.59-735.06 2
Water vapor H2O 752.033 751.28-752.79 2
Oxygen O2 773.840 773.07-774.61 2
Hydrogen cyanide HCN 797.433 794.77-798.23  
Formylium HCO+ 802.653 799.98-803.46  
Carbon monoxide CO 806.652 803.96-807.46  
Carbon C I 809.350 806.65-810.16  
Carbon monosulphide CS 832.057 829.28-832.89  
Oxygen O2 834.146 833.31-834.98  
Carbon monosulphide CS 880.899 877.96-881.78  
Water vapor H2O 916.172 915.26-917.09 2
Carbon monoxide CO 921.800 918.72-922.72 2
Carbon monosulphide CS 929.723 926.62-930.65  
Water vapor H2O 970.315 969.34-971.29 2
Carbon monosulphide CS 978.529 977.55-979.51 2
Water vapor H2O 987.927 986.94-988.92 2

NOTES:

1. The band limits are the Doppler-shifted frequencies corresponding to radial velocities of ±300 km/s (consistent with line radiation occurring in our Milky Way galaxy).

2. These lines are observable only outside the atmosphere.

SOURCE: Data and further information can be found in International Telecommunication Union, RA 314 Series: Preferred Frequency Bands for Radio Astronomical Measurements, June 2003, http://www.itu.int/dms_pubrec/itu-r/rec/ra/R-REC-RA.314-10-200306-I!!PDF-E.pdf.

Page 241 Cite
Suggested Citation: "Appendix D: International Astronomical Union Spectral Lines of Most Importance Between 300 and 1000 GHz." National Academies of Sciences, Engineering, and Medicine. 2015. Handbook of Frequency Allocations and Spectrum Protection for Scientific Uses: Second Edition. Washington, DC: The National Academies Press. doi: 10.17226/21774.
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Page 242 Cite
Suggested Citation: "Appendix D: International Astronomical Union Spectral Lines of Most Importance Between 300 and 1000 GHz." National Academies of Sciences, Engineering, and Medicine. 2015. Handbook of Frequency Allocations and Spectrum Protection for Scientific Uses: Second Edition. Washington, DC: The National Academies Press. doi: 10.17226/21774.
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Page 242
Page 243 Cite
Suggested Citation: "Appendix D: International Astronomical Union Spectral Lines of Most Importance Between 300 and 1000 GHz." National Academies of Sciences, Engineering, and Medicine. 2015. Handbook of Frequency Allocations and Spectrum Protection for Scientific Uses: Second Edition. Washington, DC: The National Academies Press. doi: 10.17226/21774.
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Next Chapter: Appendix E: International Astronomical Union Spectral Lines of Most Importance Above 1 THz
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