  The properties of the Cosmic Microwave Background (CMB) maps carry valuable
cosmological information. Here we report the results of the analysis hot and
cold CMB anisotropy spots in the BOOMERanG 150 GHz map in terms of number,
area, ellipticity, vs. temperature threshold. We carried out this analysis for
the map obtained by summing independent measurement channels (signal plus noise
map) and for a comparison map (noise only map) obtained by differencing the
same channels. The anisotropy areas (spots) have been identified for both maps
for various temperature thresholds and a catalog of the spots has been
produced. The orientation (obliquity) of the spots is random for both maps. We
computed the mean elongation of spots obtained from the maps at a given
temperature threshold using a simple estimator. We found that for the sum map
there is a region of temperature thresholds where the average elongation is not
dependent on the threshold. Its value is ~ 2.3 for cold areas and ~ 2.2 for hot
areas. This is a non-trivial result. The bias of the estimator is less than 0.4
for areas of size less than 30', and smaller for larger areas. The presence of
noise also biases the ellipticity by less than 0.3. These biases have not been
subtracted in the results quoted above. The threshold independent and random
obliquity behaviour in the sum map is stable against pointing reconstruction
accuracy and noise level of the data, thus confirming that these are actual
properties of the dataset. The data used here give a hint of high ellipticity
for the largest spots. Analogous elongation properties of CMB anisotropies had
been detected for COBE-DMR 4-year data. If this is due to geodesics mixing, it
would point to a non zero curvature of the Universe.
