The XMMPZCAT contains photometric redshifts for 100,178 X-ray sources from the 
3XMM catalogue. It is composed of X-ray sources outside the Galactic plane 
(|b|>20 deg) with highly reliable optical counterparts in the SDSS-DR13 and 
Pan-STARRS-DR1 catalogues.

To obtain the appropriate optical counterparts we used the tools and results of 
the ARCHES project (http://www.arches-fp7.eu/). We estimated the photometric 
redshifts using the MLZ-TPZ software, a supervised machine learning algorithm 
based on a supervised technique with prediction trees and random forest 
(http://matias-ck.com/mlz/).

The catalogue is presented in two FITS files. The first one 
(XMMPZCAT_PHOTZ_v2.0.fits) contains the estimated redshifts plus additional 
information about the X-ray sources, the optical counterparts and parameters 
that can help assessing the reliability of the derived photometric redshifts 
(see a detailed description below). The second file (XMMPZCAT_PDF_v2.0.fits) 
contains for each source the whole probability distribution function of the 
estimated redshift.


Changelog
============
Version 2.1: fixed an error in the proba_XMATCH column of the catalogue.
The values included in the previous version were not the correct values 
used while building the catalogue.

Version 2.0: Pan-STARRS data included in the catalogue.

Version 1.0: First preliminary release, including only data from SDSS.


XMMPZCAT_PHOTZ_v2.0.fits (Columns description)
==================================================

xmm_SRCID: Source identification label from 3XMM-DR6 catalog.

XMM RA, XMM DEC: X-ray source coordinates as in 3XMM-DR6.

XMMFITCAT: Source included in the XMM-Newton spectral-fit database.

XMATCH: Origin of the optical counterpart, ARCHES (SDSS) or XPS (Pan-STARRS).

proba_XMATCH: Probability that all counterparts are associated to the same real 
source, as estimated by xmatch.

opt_SRCID: Source identification number in SDSS-DR13 or Pan-STARRS-DR1.

Nfilters: number of magnitudes used in the photometric redshift estimation.
(u or y magnitude depending on the origin of the optical counterpart, SDSS
or Pan-STARRS, respectively).
	10: [u]griz[y]JHKw1w2
	 8: [u]griz[y]JHK
	 7: [u]griz[y]W1W2
	 5: [u]griz[y]

extended: True if the source is classified as extended in SDSS-DR10.

ph_flag: quality of the photometric data. XYZ, where X is the flag for optical 
data, Y for WISE data and Z for NIR data (2MASS, UKIDSS or VISTA). The possible 
values for X/Y/Z are:
	A: all magnitudes in this range are flagged as good
	B: some magnitudes in this range have bad photometry
	F: all magnitudes are bad
	0: no photometric data in this range

inTCS (in Training Colour Space): all colours used to calculate the photometric 
redshift are inside the colour space well covered by the training sample.

STARS: True if the source was identified as a star.

SPEC Z: Spectroscopic redshift in SDSS-DR13 (null if not available).

PHOT_Z: photometric redshift estimated by TPZ.

PHOT_ZERR: one-sigma error of the photometric redshift.

PHOT_ZCONF: confidence of the photometric redshift. It gives an idea on how 
narrowly concentrated is the redshift probability distribution around PHOT_Z.

Npeaks: number of local maxima in the PDF.

PS (Peak Strength): 1-P2/P1, where P1 is the probability density of the highest 
local maximum, and P2 is the second maximum peak. (~1: P1>>P2, ~0: P2~P1).

PHOT_Z2: redshift position of P2.



XMMPZCAT_PDF_v2.0.fits (Columns description)
======================================================

xmm_SRCID: Source identification label from 3XMM-DR6 catalog.

PDF_z: array containing redshifts values.

PDF: array containing the probability density of the redshift given in the 
corresponding PDF_z value.