
Research Groups
Extragalactic Astrophysics (Lead: Prof. Carollo) 
Observational Cosmology (Lead: Prof. Lilly) 
Star and Planet Formation (Lead: Prof. Meyer) 
Cosmology (Lead: Prof. Refregier) 
Black Holes (Lead: Prof. Schawinski) 
ZEBRA is a free and opensource software distributed under the GNU General Public License 3 and can be downloaded here.
ZEBRA combines and extends several of the classical approaches to produce accurate photometric redshifts down to faint magnitudes. In particular, ZEBRA uses the templatefitting approach to produce Maximum Likelihood and Bayesian redshift estimates based on:
The workflow of ZEBRA. The input files are indicated on the top. The resulting output data on the bottom. A typical ZEBRA session would take the following route: 1) Check & correction of the photometric catalog; 2) Optimization of the spectral energy distributions (templates); 3) MaximumLikelihood fit or Bayesian estimation of the probability distribution in template type  redshift space.
The user can choose from, or has otherwise to provide, an initial set of templates and filter transmission curves. In addition a catalog is needed which provides ZEBRA with the magnitudes of the galaxies in question in the various filter bands.
In Feldmann et al. 2006 we have demonstrated ZEBRA's performance using the Subaru, CFHT and NOAO groundbased photometry (Capak et al. 2006; Taniguchi et al. 2006; ApJ COSMOS Special issue) on a sample of ~50,000 COSMOS galaxies and, as a training set, zCOSMOS spectroscopic redshifts that were available for 1.8% of the sample under study.
a) 
b) 
c) 
A simple MaximumLikelihood estimate of redshifts without template optimization; (top) spectroscopic vs. photometric redshifts; (bottom) the error in the redshift estimation as function of redshift for different template types. 
ZEBRA's MaximumLikelihood estimate of redshifts with template optimization. Top and bottom panel as in a). 
ZEBRA's Bayesian estimate of redshifts with template optimization. Top and bottom panels as in a). 
standard deviation of dz/1+z ~ 0.043 outlier fraction ~ 2.1 % 
standard deviation of dz/1+z ~ 0.027 outlier fraction ~ 1.1 % 
standard deviation of dz/1+z ~ 0.027 outlier fraction ~ 0.8 % 
In order to run ZEBRA on your machine you may try to download an appropriate, precompiled ZEBRA binary. Alternatively you can download the ZEBRA package and compile the code yourself. Please refer to the ZEBRA user manual on how to install ZEBRA properly. The ZEBRA package includes: the source code, examples on how to use ZEBRA, wrapper scripts and the user manual.
Latest stable version  v1.10  09.02.2013  
Type 
Target Platform 
File 
Remarks 
Binary  Linux 64 bit  x86  zebra  gsl statically linked 
Binary 
Mac OS X 10.8  Intel 
zebra 
gsl statically linked 
Source 
Unix / Linux / Mac OS 
zebra1.10.09Feb2013.tar.gz 
incl. source code, examples, wrapper scripts, manual 
Manual 
any 
user_manual_ZEBRA.pdf 
http://arxiv.org/abs/0801.3275 
A note about binaries: We recommend the installation of ZEBRA from source as described in the user manual. Installation from source requires lapack and the GNU Scientific Library (gsl).
Please report any bugs or problems you encounter with the code to: zebra@phys.ethz.ch.
If you are intending to extend / improve ZEBRA it would be kind to let us know as well.
It is kindly requested that the use of ZEBRA should be acknowledged with an explicit reference to Feldmann, Carollo, Porciani, Lilly et al., MNRAS 372, 564 (2006) in the bibliographic list of any resulting publication.
A new version of ZEBRA (ZEBRA+) is currently being built in order to:
Stay tuned!
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