  We report on the discovery and monitoring observations of a new galactic
black hole candidate XTE J1752-223 by Rossi X-ray Timing Explorer (RXTE). The
new source appeared on the X-ray sky on October 21 2009 and was active for
almost 8 months. Phenomenologically, the source exhibited the
low-hard/high-soft spectral state bi-modality and the variability evolution
during the state transition that matches standard behavior expected from a
stellar mass black hole binary. We model the energy spectrum throughout the
outburst using a generic Comptonization model assuming that part of the input
soft radiation in the form of a black body spectrum gets reprocessed in the
Comptonizing medium. We follow the evolution of fractional root-mean-square
(RMS) variability in the RXTE/PCA energy band with the source spectral state
and conclude that broad band variability is strongly correlated with the source
hardness (or Comptonized fraction). We follow changes in the energy
distribution of rms variability during the low-hard state and the state
transition and find further evidence that variable emission is strongly
concentrated in the power-law spectral component. We discuss the implication of
our results to the Comptonization regimes during different spectral states.
Correlations of spectral and variability properties provide measurements of the
BH mass and distance to the source. The spectral-timing correlation scaling
technique applied to the RXTE observation during the hard-to-soft state
transition indicates a mass of the BH in XTE J1752-223 between 8 and 11 solar
masses and a distance to the source about 3.5 kiloparsec.
