Recent and most sensitive CMB Temperature below 5 GHz. TRIS data are marked as open squares. An improvement of more a factor of 10 was gained at frequencies below 1 GHz. 0.600 GHz T=2.685 +/- 0.054 TRIS (open square) 0.820 GHz T=2.772 +/- 0.266 TRIS (open square) 1.280 GHz T=3.450 +/- 0.780 Raghunathan & Subrahmanyan (2000) 1.410 GHz T=2.110 +/- 0.380 Levin et al. (1988) 1.425 GHz T=2.650 +/- 0.330 Staggs & al. (1996) 1.470 GHz T=2.260 +/- 0.190 Bensadoun et al. (1993) 2.000 GHz T=2.550 +/- 0.140 Bersanelli et al. (1994) 2.500 GHz T=2.620 +/- 0.250 Sironi et al. (1984) 2.500 GHz T=2.518 +/- 0.395 TRIS (open square) 2.500 GHz T=2.790 +/- 0.150 Sironi & Bonelli (1986) 2.500 GHz T=2.500 +/- 0.250 Sironi et al. (1991) 3.700 GHz T=2.590 +/- 0.130 De Amici et al. (1988) 3.800 GHz T=2.560 +/- 0.080 De Amici et al. (1990) 3.800 GHz T=2.710 +/- 0.070 De Amici et al. (1990) 3.800 GHz T=2.640 +/- 0.070 De Amici et al. (1991) 4.750 GHz T=2.710 +/- 0.200 Mandolesi et al. (1984) 4.750 GHz T=2.700 +/- 0.070 Mandolesi et al. (1986)