Measurements of the cosmic microwave background temperature at 1.47 GHz

Abstract

A radiofrequency-gain total power radiometer measured the intensity of the cosmic microwave background (CMB) at a fr_uency of 1.47 GHz (20.4 cm wavelength) from White Mountain, California, in September 1988 and from the South Pole, Antarctica, in December 1989. The CMB thermodynamic temperature, TCMB, is 2.27 :!: 0.25 K (68% C.L.) measured from White Mountain and 2.26 :t:0.21 K from the South Pole site. The combined result is 2.27 :!:0.19 K. The correction for galactic emission has been derived from sealed low-fr_uency maps and constitutes the main source of error. The _tmospherie signal is found by extrapolation from zenith scan measurements at higher frequencies. The result is consistent with previous low-frequency measurements, including a measurement at 1.41 GHz (l.,¢vinet al. 1988) made with an earlier version of. this instrument. The result is-2.5 o (-1% probability) from the 2.74 + 0.02K global average CMB temperature.

A radio continuum survey of the southern sky at 1420 MHz

“…• , we found a difference to the data of Bensadoun et al (1993) of +0.53 K. The derived cosmic microwave background temperature by Bensadoun et al (1993) at 1.47 GHz of 2.26 ± 0.19 K differs by 0.44 K to that assumed by Reich & Reich (1988a) of 2.7 K. However, there is an additional measurement of the cosmic microwave background of the northern sky at 1.4 GHz by Staggs et al (1996). Their result is 2.65 +0.33 −0.30 K, rather close to the adopted temperature of 2.7 K for the northern sky.…”

“…Absolute temperatures have been measured by Bensadoun et al (1993), who have performed sky-horn measurements at various declinations of the northern but also of the southern sky by using the same equipment to determine the cosmic microwave background temperature at 1.47 GHz. The resolution of these data is 30…”

“…the mean of both the differences mentioned above) as the best compromise for a correction of the Bensadoun et al (1993) data and added this value to the measurements at declination −75…”

TRIS. II. Search for CMB Spectral Distortions at 0.60, 0.82, and 2.5 GHz

“…These measurements give temperatures of the CMB that, within the error bars, are in agreement with the temperature measured by FIRAS at much higher frequencies. The only exceptions are the results obtained at 1.4 GHz by Levin et al (1988) and Bensadoun et al (1993). It is hard to fit these results only with the spectral distortions allowed by COBE FIRAS (see Fixen et al 1996).…”

A research program to map the Galactic Emission at low frequencies

“…Complete radio maps of the galaxy are useful not only for galactic studies, but they are also required in the analysis and interpretation of the recently discovered (Smoot et al 1992) anisotropies of the cosmic microwave background (CMB) as well as on the measurements of its spectral distribution (Banday et al 1991, Bensadoun et al 1993.…”