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22 GHz / 1.3 cm Spectroscopy with the 26m telescope

Table 1. 22 - 24 GHz / 1.3 cm Receiver characteristics. Point source sensitivity (i.e. aperture efficiency) is strongly dependent on angle away from zenith. The zenith system temperature is strongly weather dependent. The receiver temperature is 200K.
Receiver type dual uncooled HEMTs
Polarization LCP + RCP
RF filter 22000-24000 MHz
Zenith System temperature 235 K
Point Source Sensitivity 10.5 Jy/K/Pol
System Equivalent Flux Density 5000 Jy
Half Power Beamwidth 0.036 degrees

Table 2. Stronger lines observable at 22 - 24 GHz
Spectral Line Rest Frequency (MHz)
20-3-1 Water vapour22235.120
H66alpha22364.176
Methanol CH3OH 9(2,7)-10(1,10) A+23121.024
H65alpha23404.289
Ammonia NH3 1(1)-1(1) F,F1=5/2,2-5/2,223694.5060
Ammonia NH3 2(2)-2(2) F1=3-323722.6336
Ammonia NH3 3(3)-3(3) F1=4-423870.1296
Ammonia NH3 4(4)-4(4)24139.4169

Table 3. Velocity range, spectral resolution with 1024 channels, and minimum rms noise after 1 minute integration, for the given correlator bandwidth, for each sense of polarized radiation, at 22235 MHz.
Correlator Velocity Correlator RMS Noise RMS Noise
Bandwidth Range Resolution in 1 min in 1 min
MHz km/s km/s K Jy
32.000 431.7 0.422 0.225 2.26
16.000 215.9 0.211 0.319 3.29
8.000 107.9 0.105 0.451 4.51
4.000 54.0 0.053 0.638 6.38
2.000 27.0 0.026 0.902 9.02
1.000 13.5 0.013 1.276 12.76
0.500 6.8 0.006 1.804 18.04
0.250 3.4 0.003 2.551 25.51
0.125 1.7 0.0016 3.608 36.08