On the RMS Anisotropy at 7 degrees and 10 degrees in the COBE-DMR Two-Year Sky Maps

The frequency-independent rms temperature fluctuations determined from the Cosmic Background Explorer-Differential Microwave Radiometer (COBE-DMR) two-year sky maps are used to infer the parameter Q_rms-PS, which characterizes the normalization of power-law models of primordial cosmological temperature anisotropy, for a forced fit to a scale-invariant Harrison-Zel'dovich (n = 1) spectral model. Using a joint analysis of the 7 deg and 10 deg 'cross'-rms derived from both the 53 and 90 GHz sky maps, we find Q_rms-PS = 17.0_-2.1^+2.5 micro Kelvin when the low quadrupole is included, and Q_rms-PS = 19.4_-2.1^+2.3 micro Kelvin excluding the quadrupole. These results are consistent with the n = 1 fits from more sensitive methods. The effect of the low quadrupole derived from the COBE-DMR data on the inferred Q_rms-PS normalization is investigated. A bias to lower Q_rms-PS is found when the quadrupole is included. The higher normalization for a forced n = 1 fit is then favored by the cross-rms technique.