Lifting the dust veil from the Globular Cluster Palomar2
  This work employs high-quality {\em Hubble Space Telescope} ({\em HST})
Advanced Camera for Surveys (ACS) F606W and F814W photometry to correct for the
differential reddening affecting the colour-magnitude diagram (CMD) of the
poorly-studied globular cluster (GC) Palomar\,2. Differential reddening is
taken into account by assuming that morphological differences among CMDs
extracted across the field of view of Palomar\,2 correspond essentially to
shifts (quantified in terms of $\delta E(B-V)$) along the reddening vector due
to a non-uniform dust distribution. The average reddening difference over all
partial CMDs is $\overline{\delta E(B-V)}=0.24\pm0.08$, with the highest
reaching $\delta E(B-V) =0.52$. The corrected CMD displays well-defined and
relatively narrow evolutionary sequences, especially for the evolved stars,
i.e. the red-giant, horizontal and asymptotic giant branches (RGB, HB and AGB,
respectively). The average width of the upper main sequence and RGB profiles of
the corrected CMD corresponds to 56\% of the original one. Parameters measured
on this CMD show that Palomar\,2 is $\approx13.25$\,Gyr old, has the mass
$M\sim1.4\times10^5\,m_\odot$ stored in stars, is affected by the foreground
$E(B-V)\approx0.93$, is located at $d_\odot\approx26$\,Kpc from the Sun, and is
characterized by the global metallicity $Z/Zo\approx0.03$, which corresponds to
the range $-1.9\leq [Fe/H] \leq-1.6$ (for $0.0\leq[\alpha/Fe]\leq+0.4$), quite
consistent with other outer halo GCs. Additional parameters are the absolute
magnitude $M_V\approx-7.8$, and the core and half-light radii
$r_C\approx2.6$\,pc and $R_{HL}\approx4.7$\,pc, respectively.
