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Handbook of Frequency Allocations and Spectrum Protection for Scientific Uses (2007)

Chapter: Appendix C International Astronomical Union Spectral Lines of Most Importance Below 300 GHz

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Suggested Citation:"Appendix C International Astronomical Union Spectral Lines of Most Importance Below 300 GHz." National Research Council. 2007. Handbook of Frequency Allocations and Spectrum Protection for Scientific Uses. Washington, DC: The National Academies Press. doi: 10.17226/11719.
×

Appendix C
International Astronomical Union Spectral Lines of Most Importance Below 300 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 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 below 300 GHz are listed in Table C.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 the Galaxy. These data and further information can be found on the Web site of the European Science Foundation’s Committee on Radio Astronomy Frequencies at http://www.astron.nl/craf/iaulist.htm.)

Suggested Citation:"Appendix C International Astronomical Union Spectral Lines of Most Importance Below 300 GHz." National Research Council. 2007. Handbook of Frequency Allocations and Spectrum Protection for Scientific Uses. Washington, DC: The National Academies Press. doi: 10.17226/11719.
×

TABLE C.1 The Most Important Spectral Lines Below 275 GHz

Substance

Formula

Frequency (GHz)

Suggested Minimum Band (GHz)

Band Allocation Status1

Deuterium

D I

0.327384

0.327-0.3277

P

Hydrogen

HI

1.4204062,3

1.370-1.427

S 1.33-1.40

 

 

 

 

P 1.40-1.427

Hydroxyl radical

OH

1.6122314,5

1.6068-1.6138

P 1.6106-1.6138

 

 

1.6654026

1.6598-1.6671

P 1.66-1.67

 

 

1.6673596

1.6618-1.6690

 

Hydroxyl radical

OH

1.7205303,6

1.7148-1.7222

S 1.7188-1.7222

Methyladyne

CH

3.2637943,6

3.2424-3.2671

S 3.260-3.267

 

 

3.3354813,6

3.3244-3.3388

S 3.332-3.339

 

 

3.3491933,6

3.3380-3.3525

S 3.3458-3.3525

Formaldehyde

H2CO

4.8296603,6

4.8136-4.8345

S 4.8-4.9

Methanol

CH3OH

6.6685183,7

6.6618-6.6752

S 6.650-6.6752

Helium

3He+

8.665650

8.6570-8.6743

 

Methanol

CH3OH

12.1783,8

12.17-12.19

 

Formaldehyde

H2CO

14.4883,6

14.44-14.50

S 14.47-14.50

Cyclopropenylidene

C3H2

18.3433,6,8

18.28-18.36

 

Water vapor

H2O

22.2353,6

22.16-22.26

F 22.01-22.21

 

 

 

 

P 22.21-22.50

Dicarbon monosulphide

CCS

22.344

22.32-22.37

 

Ammonia

NH3

23.6946

23.61-23.89

P 23.60-24.00

 

 

23.7236

23.8706

 

Sulphur monoxide

SiO

30.002

29.97-30.03

 

Methanol

CH3OH

36.169

36.13-36.21

P9 36-37

Silicon monoxide

SiO

42.519

42.47-42.57

 

 

 

42.821

42.78-42.86

F 42.77-42.87

 

 

43.122

43.08-43.17

F 43.07-43.17

 

 

43.424

43.38-43.47

F 43.37-43.37

Dicarbon monosulphide

CCS

45.379

45.33-45.42

 

Carbon monosulphide

CS

48.991

48.94-49.04

P 48.94-49.04

Oxygen

O2

61.1

56.21-63.06

P10 58.2-59.0

Deuterated water

HDO

80.578

80.50-80.66

 

Cyclopropenylidene

C3H2

85.339

85.05-85.42

 

Silicon monoxide

SiO

86.243

86.16-86.33

P

Formylium

H13CO+

86.754

86.67-86.84

P

Silicon monoxide

SiO

86.847

86.76-86.93

P

Ethynyl radical

C2H

87.30011

87.21-87.39

P

Suggested Citation:"Appendix C International Astronomical Union Spectral Lines of Most Importance Below 300 GHz." National Research Council. 2007. Handbook of Frequency Allocations and Spectrum Protection for Scientific Uses. Washington, DC: The National Academies Press. doi: 10.17226/11719.
×

Substance

Formula

Frequency (GHz)

Suggested Minimum Band (GHz)

Band Allocation Status1

Hydrogen cyanide

HCN

88.6326

88.34-88.72

P

Formylium

HCO++

89.1896

88.89-89.28

P

Hydrogen isocyanide

HNC

90.664

90.57-90.75

P

Diazenylium

N2H+

93.174

93.08-93.27

 

Carbon monosulphide

CS

97.9816

97.65-98.08

 

Sulfur monoxide

SO

99.300

99.20-99.40

 

Methyl acetylene

CH3CCH

102.5

102.39-102.60

 

Methanol

CH3OH

107.014

106.91-107.12

 

Carbon monoxide

C18O

109.782

109.67-109.89

P

Carbon monoxide

13CO

110.2016

110.83-110.31

P

Carbon monoxide

C17O

112.3598

112.25-112.47

P

Cyano radical

CN

113.500

113.39-113.61

P

Carbon monoxide

CO

115.2716

114.88-115.39

P

Oxygen

O2

118.750

118.63-118.87

P6 116-126

Formaldehyde

H213CO

137.4503,8

137.31-137.59

 

Formaldehyde

H2CO

140.840

140.69-140.98

P

Carbon monosulphide

CS

146.969

146.48-147.12

P 146.82-147.12

Nitric oxide

NO

150.4

149.95-150.85

S 150-151

Methanol

CH3OH

156.602

156.45-156.76

 

Water vapor

H2O

183.310

183.13-183.49

 

Carbon monoxide

C18O

219.560

219.34-219.78

P

Carbon monoxide

13CO

220.3996

219.67-220.62

P

Cyano radical

CN

226.600

226.37-226.83

P

Cyano radical

CN

226.800

226.57-227.03

P

Carbon monoxide

CO

230.5386

229.77-230.77

P

Carbon monosulphide

CS

244.9538

244.14-245.20

 

Nitric oxide

NO

250.6

250.35-250.85

P

Ethynyl radical

C2H

262.000

261.74-262.26

 

Hydrogen cyanide

HCN

265.886

265.00-266.15

 

Formylium

HCO++

267.557

266.66-267.82

 

Hydrogen isocyanide

HNC

271.981

271.71-272.25

 

Carbon monosulphide

13CS

277.455

277.18-277.73

 

Diazenylium

N2H+

279.511

279.23-279.79

 

Carbon monosulphide

C34S

289.209

288.92-289.50

 

Sodium hydride

NaH

289.860

289.57-290.15

 

Carbon monosulphide

CS

293.912

292.93-294.21

 

Suggested Citation:"Appendix C International Astronomical Union Spectral Lines of Most Importance Below 300 GHz." National Research Council. 2007. Handbook of Frequency Allocations and Spectrum Protection for Scientific Uses. Washington, DC: The National Academies Press. doi: 10.17226/11719.
×

NOTE: Definitions of abbreviations for the various services referred to in the footnotes to this table are provided in Appendix I.

1P: primary allocation, S: secondary allocation, F: protection by footnote.

2An extension to lower frequencies of the allocation of 1400-1427 MHz is required to allow for the Doppler shifts for HI observed in distant galaxies.

3For passive EESS and SRS, along with FS and MS.

4The current international allocation is not primary and/or does not meet bandwidth requirements. See the ITU-R Radio Regulations for more detailed information.

5Because these line frequencies are also being used for observing other galaxies, the listed bandwidths include Doppler shifts corresponding to radial velocities of up to 1000 km/s. It should be noted that HI has been observed at frequencies redshifted to 500 MHz, while some lines of the most abundant molecules have been detected in galaxies with velocities up to 50,000 km/s, corresponding to a frequency reduction of up to 17%.

6For passive EESS and SRS, along with FS and MS.

7This line is not mentioned in Article 8 of the ITU-R Radio Regulations.

8For passive EESS and SRS, along with FS and MS.

9For passive EESS and SRS, with secondary allocations to FS and MS.

10United States only.

11There are six closely spaced lines associated with this molecule at this frequency. The listed band is wide enough to permit observations of all six lines.

SOURCE: Data and further information can be found at the Web site of the European Science Foundation’s Committee on Radio Astronomy Frequencies at http://www.astron.nl/craf/iaulist.htm, accessed October 26, 2005.

Suggested Citation:"Appendix C International Astronomical Union Spectral Lines of Most Importance Below 300 GHz." National Research Council. 2007. Handbook of Frequency Allocations and Spectrum Protection for Scientific Uses. Washington, DC: The National Academies Press. doi: 10.17226/11719.
×
Page 98
Suggested Citation:"Appendix C International Astronomical Union Spectral Lines of Most Importance Below 300 GHz." National Research Council. 2007. Handbook of Frequency Allocations and Spectrum Protection for Scientific Uses. Washington, DC: The National Academies Press. doi: 10.17226/11719.
×
Page 99
Suggested Citation:"Appendix C International Astronomical Union Spectral Lines of Most Importance Below 300 GHz." National Research Council. 2007. Handbook of Frequency Allocations and Spectrum Protection for Scientific Uses. Washington, DC: The National Academies Press. doi: 10.17226/11719.
×
Page 100
Suggested Citation:"Appendix C International Astronomical Union Spectral Lines of Most Importance Below 300 GHz." National Research Council. 2007. Handbook of Frequency Allocations and Spectrum Protection for Scientific Uses. Washington, DC: The National Academies Press. doi: 10.17226/11719.
×
Page 101
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The electromagnetic spectrum is a vital part of our environment. Information encoded in the spectrum of radiation arriving at earth from the universe is the means by which we learn about its workings and origin. Radiation collected from the Earth's land, oceans, biosphere, and atmosphere provide us with much of the data needed to better understand this environment. Wise use of the spectrum is necessary if we are to continue these advances in scientific understanding. To help guide this effort, the NSF and NASA asked the NRC to develop a set of principles for fostering effective allocation and protection of spectral bands for scientific research. This handbook contains practical information in this connection including a description of regulatory bodies and issues, a discussion of the relevant scientific background, a list of science spectrum allocations in the United States, and an analysis of spectrum protection issues.

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