Appendix: Typical GBT Performance.

This table lists typical system temperatures (Tsys), gains, and aperture efficiencies measured at high elevation in good weather. Typical zenith tau is given for clear weather low humidity conditions. There is virtually no change in aperture efficiency with elevation for frequencies of 3 GHz and lower.

The active surface should be used for frequencies of 8 Ghz and higher.

1 2 3 4 5 6 7
Receiver FWHM Tsys Gain
(K/Jy) 		Aperture.Eff. SEFD (Jy) Zenith Tau
Rcvr_342 36' 70 K 2.0 70% 35
Rcvr_450 27' 57 K 2.0 70% 28
Rcvr_600 21' 48 K 2.0 70% 24
Rcvr_800 15' 25 K 2.0 70% 12
Rcvr_1070 12' 22 K 2.0 70% 11
Rcvr1_2 9' 20 K 2.0 70% 10
Rcvr2_3 5.8' 22 K 1.9 68% 12 0.01
Rcvr4_6 2.5' 25 K 1.85 65% 14 0.01
Rcvr8_10 1.4' 27 K 1.8 63% 15 0.02
Rcvr12_15 54" 30 K 1.7 60% 18 0.03
Rcvr18_22 37" 30-40 K 1.5 55% 23 0.05
Rcvr22_26 30" 30-40 K 1.5 55% 24 0.05
Rcvr26_40 22" ~40 K 1.2 45% 50 0.04
Rcvr40_52 16" 43GHz: 60 K
48GHz: 80 K
50GHz: 130 K 		1.0 35-40% 43GHz: 60
48GHz: 80
50GHz: 130 		0.07
0.17
0.3