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OCR for page 98
Handbook of Frequency Allocations and Spectrum Protection for Scientific Uses
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.)
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Handbook of Frequency Allocations and Spectrum Protection for Scientific Uses
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
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Handbook of Frequency Allocations and Spectrum Protection for Scientific Uses
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
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Handbook of Frequency Allocations and Spectrum Protection for Scientific Uses
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.
Representative terms from entire chapter:
mean power