Observations of the Isotropy of the Cosmic Microwave Background Radiation

Annu. Rev. Astron. Astrophys. 1992. 30: 653-703
Copyright © 1993 by Annual Reviews. All rights reserved

3.3.2 OBSERVATIONS IN ANTARCTICA Andreani et al have carried out observations in Antarctica at wavelengths of 2 mm, 1 mm and 350 µm (Andreani et al 1990a, b, 1991a, b). Their instrument was an off-axis parabola flux collector 1 meter in diameter with a 1° beam. The flux collector was wobbled at 8 Hz to give a beamthrow of 2°.5 on the sky. Their 2 mm observations showed a correlation with the IRAS 100 µm data, and they concluded that they had detected a cold (6-15 K) dust component which was well correlated with a warmer (~ 30 K) dust component detected by IRAS. They therefore extrapolated the IRAS 100 µm measurements to 2 mm, using the spectrum given by Andreani et al (1990b), and subtracted them from their 2 mm observations. They found that by this means they were able to reduce the variance in their 2 mm observations by a factor two. This still left detectable signals in their observations, which were unexplained, but they adopted a conservative approach and used the results to place the upper limit on fluctuations given in Table 4.

**Table 4.** 95% upper limits ^a on *T/T* at angular scales 1-20°

Experiment	Angular Scale	T/T x 10⁵	Comments

Timbie & Wilkinson 1990	1°.7	7.4	43 GHz; monochromatic W(k)
	1°.1	11	LR test, ~ 0.55; Gaussian W(k)
	0°.4-3°.5	20	LR test, ~ 0.55; Gaussian W(k)
Andreani et al. 1990a	2°.5	33	150 GHz
	5°	29
Mandolesi et al. 1986	2°-10°	50-70	10 GHz
Cottingham	3°-25°	20	19.2 GHz; Monte Carlo tests on S'; Gaussian W(k)
Boughn et al 1991	3°	10	19.2 GHz; Monte Carlo teste on S'; Gaussian W(k)
	30°	4	Monte Carlo teste on S'; Gaussian W(k)
Page et al. 1990	10°	9.3	168 GHz; LR test, = 0.7; monochromatic W(k)
Meyer et al. 1991	13°	1.6	168 GHz; Monte Carlo tests on S', =0.92; monochromatic W(k)
	3°-22°	4	Monte Carlo tests on S'; Gaussian W(k)

^a As described in the text, some of these observations detected excess variance which could not be definitely attributed to the cosmic microwave background radiation.