The Massive Galaxy Cluster XMMU J1230.3+1339 at z ~ 1: Colour-magnitude
  relation, Butcher-Oemler effect, X-ray and weak lensing mass estimates
  We present results from the multi-wavelength study of XMMU J1230.3+1339 at z
~ 1. We analyze deep multi-band wide-field images from the Large Binocular
Telescope, multi-object spectroscopy observations from VLT, as well as
space-based serendipitous observations, from the GALEX and Chandra X-ray
observatories. We apply a Bayesian photometric redshift code to derive the
redshifts using the FUV, NUV and the deep U, B, V, r, i, z data. We achieve an
accuracy of $\triangle z/(1+z)$ = 0.07 (0.04) and the fraction of catastrophic
outliers is $\eta$ = 13 (0)%, when using all (secure) spectroscopic data,
respectively. The i - z against z colour-magnitude relation of the photo-z
members shows a tight red-sequence with a zero point of 0.935 mag, and slope
equal to -0.027. We observe evidence for a truncation at the faint end of the
red-cluster-sequence and the Butcher-Oemler effect, finding a fraction of blue
galaxies $f_b \approx$ 0.5. Further we conduct a weak lensing analysis of the
deep 26' $\times$ 26' r-band LBC image. The observed shear is fitted with a
Single-Isothermal-Sphere and a Navarro-Frenk-White model to obtain the velocity
dispersion and the model parameters, respectively. Our best fit values are, for
the velocity dispersion $\sigma_{SIS}$ = 1308 $\pm$ 284, concentration
parameter c = 4.0$^{+14}_{-2}$ and scale radius r$_{s}$ = 345$^{+50}_{-57}$
kpc. Combining our mass estimates from the kinematic, X-ray and weak lensing
analyses we obtain a total cluster mass of $M^{tot}_{200}$ = (4.56 $\pm$ 2.3)
$\times$ 10$^{14}$ M$_{\sun}$. This study demonstrates the feasibility of
ground based weak lensing measurements of galaxy clusters up to z ~ 1.
