TRIS II: search for CMB spectral distortions at 0.60, 0.82 and 2.5 GHz

Understand

With the TRIS experiment we have performed absolute measurements of the sky brightness in a sky circle at $\delta = +42^{\circ}$ at the frequencies $\nu =$ 0.60, 0.82 and 2.5 GHz.

• In this paper we discuss the techniques used to separate the different contributions to the sky emission and give an evaluation of the absolute temperature of the Cosmic Microwave Background.
• For the black-body temperature of the CMB we get: $T_{cmb}^{th}=(2.837 \pm 0.129 \pm 0.066)K$ at $\nu=0.60$ GHz; $T_{cmb}^{th}=(2.803 \pm 0.051 ^{+0.430} _{-0.300})K$ at $\nu=0.82$ GHz; $T_{cmb}^{th}=(2.516 \pm 0.139 \pm 0.284)K$ at $\nu=2.5$ GHz.
• The first error bar is statistic (1$\sigma$) while the second one is systematic.