Euclid – France atelier/workshop gravitational lensing

Date: October 22, 2018

Organizer:  Martin Kilbinger & Karim Benabed

Venue: IAP,  98bis bd Arago, 75014 Paris. Salle Entresol

Local information


Martin Kilbinger
Karim Benabed
Sandrine Codis
Eric Jullo
Francis Bernardeau
Yohan Dubois
Santiago Casas
Raphael Gavazzi
Alain Blanchard
Patrick Hudelot
Calum Murray
Matteo Rizzato
Samuel Farrens
Alexandre Barthelemy
Austin Peel
Nicolas Martinet
Morgan Schmitz
Virginia Ajani
Henry McCracken
Peter Taylor
Bertrand Morin
Céline Gouin



10:00   Café
10:30   Martin Kilbinger                Welcome, introduction, goals of the meeting, resources
10:45   Matteo Rizzato                   Information content in the weak lensing bispectrum
11:15   Eric Jullo                                 WLSWG work package “Galaxy-galaxy lensing”
11:45   Alexandre Barthelemy    One-point statistics of weak lensing maps
12:15    Peter Taylor                         k-cut Cosmic Shear: Tunable Power Spectrum Sensitivity to Test Gravity
12:45   Henry Joy McCracken    Euclid VIS activities and weak lensing requirements
13:00   Lunch
14:15   Austin Peel                           Peak counts: breaking degeneracies & machine learning
14:45   Nicolas Martinet               WL peak/mass mapping/shear calibration
15:15   Céline Gouin                       The impact of baryons on WL statistics
15:45   Bertrand Morin                  COSEBIs - Implementation of cosmic shear E-/B- modes
16:15   Martin Kilbinger, all          WL projects in Euclid-France, discussion, future plans
17:15   End



École Euclid de cosmologie 2018

Date: August 20 - September 1, 2018

Venue: Roscoff, Bretagne, France


Lecture ``Weak gravitational lensing'' (Le lentillage gravitationnel), Martin Kilbinger.

Find here links to the lecture notes, TD exercises, "tables rondes" topics, and other information.

  • Resources.
    • A great and detailed introduction to (weak) gravitational lensing are the 2005 Saas Fee lecture notes by Peter Schneider. Download Part I (Introduction to lensing) and Part III (Weak lensing) from my homepage.
    • Check out Sarah Bridle's video lectures on WL from 2014.
  • TD cycle 1+2, Data analysis.
    1.  We will work on a rather large (150 MB) weak-lensing catalogues from the public CFHTLenS web page. During the TD I will show instructions how to create and download this catalogue. These catalogues will also be available on the virtual machine for the school.
      If you like, you can however download the catalogue on your laptop at home. Please have a look at the instructions in the TD slides.
    2. If you want to do the TD on your laptop, you'll need to download and install athena (the newest version 1.7). Available on the VM.
    3.  For one of the bonus TD you'll need a new version of (v 1.8beta). Download it here. Available on the VM.
  • Lecture notes and exercise classes.  You can already download the slides in one file (40 - 60 MB), but be ware that the content will still change slightly until the classes.
    • Part I (Cycle 1):    [all | day 1 (1/6)  |   day 2 (2/6) |  day 3 (3/6)]
    • Part II (Cycle 2):  [all | day 1 (4/6)   |   day 2 (5/6)  | day 3 (6/6)]
    • TD:                             [1/2 and 2/2]
    • Table Ronde sujet
  • Slack channel:

Cosmological parameters from weak cosmological lensing


Authors: M. Kilbinger
Year: 07/2018
Download: ADS| Arxiv


In this manuscript of the habilitation à diriger des recherches (HDR), the author presents some of his work over the last ten years. The main topic of this thesis is cosmic shear, the distortion of images of distant galaxies due to weak gravitational lensing by the large-scale structure in the Universe. Cosmic shear has become a powerful probe into the nature of dark matter and the origin of the current accelerated expansion of the Universe. Over the last years, cosmic shear has evolved into a reliable and robust cosmological probe, providing measurements of the expansion history of the Universe and the growth of its structure.
I review the principles of weak gravitational lensing and show how cosmic shear is interpreted in a cosmological context. Then I give an overview of weak-lensing measurements, and present observational results from the Canada-France Hawai'i Lensing Survey (CFHTLenS), as well as the implications for cosmology. I conclude with an outlook on the various future surveys and missions, for which cosmic shear is one of the main science drivers, and discuss promising new weak cosmological lensing techniques for future observations.




Authors: M. Kilbinger
Language: C
Download: athena_1.7.tgz
Description: A tree code for calculating second-order correlation functions.

athena: Tree code for second-order correlation functions

athena olive tree Martin Kilbinger, CEA Saclay, Service d'Astrophysique (SAp), France

METHOD athena is a 2d-tree code written in C, which estimates second-order correlation functions from input galaxy catalogues. These include shear-shear correlations (cosmic shear), position-shear (galaxy-galaxy lensing) and position-position (spatial angular correlation).

  DOWNLOAD Get the latest version athena_1.7.tgz. A readme file is available. Run the code on the test data set. New features and bug fixes in version 1.7 (Mar 2014):

  • General
    • Added FITS file support. Input catalogues and output correlation function files can be both in ascii or fits format.
      (Note: If reading a FITS file causes a segmentation fault, remove the compiler option "-std=c99", either from CMakeLists.txt or src/Makefile.athena".)
    • Format of resample files changed, only relevant columns are output.
    • Compilation of code automated using cmake. Alternatively, the traditional Makefile is still usable.
    • Directory structure changed.

To compile and run the code, you need a C-compiler. To calculate the angular correlation function, including reading mask files and creating random catalogues, gsl and perl and required. The library cfitsio is optional (for FITS file support).

Further scripts are part of the athena package:

  • The python script calculates (band-)power spectrum by integrating over the correlation function using an estimator from this paper. Further, the aperture-mass dispersion is compuated, also via integrating the correlation function.
  • The perl script is the master script for angular correlation function calculations. It creates random catalogues and calls athena for all necessary combinations of data and random catalogues, including redshift bins, and outputs the Landy & Szalay (1993) and Hamilton (1993) estimators of the correlation function.
  • Two perl scripts ( and calculate projections of an input catalogue in spherical coordinates, and transform an arbitrary (ascii) input catalogue into an athena-readable format.
  • The python script runs a series of tests for easy comparison with expected results.
  • Various scripts to transform and plot resampled data (e.g. Jackknife)

  • For older versions of athena please contact me (martin.kilbinger at


Martin Kilbinger
Christopher Bonnett (gal-gal lensing)
Jean Coupon (venice)

With helpful suggestions from Henry McCracken, Lance Miller, and Barnaby Rowe. Ami Choi, Jonathan Benjamin, Matthieu Béthermin, and Shahab Joudaki are thanked for testing the code and bug-hunting.

Please feel free to send questions, feedback and bug reports to If you want to be added to the athena mailing list, to get updates about new versions and bug-fixes, send me a mail to

CosmoPMC (cosmology sampling with Population Monte Carlo [PMC])
nicaea (cosmology and lensing package)
reduced-shear corrections home

Last updated February 2017.



Authors: Chieh-An Lin
Language: C
Download: GitHub
Description: A code for fast weak lensing peak count modelling.

Counts of Amplified Mass Elevations from Lensing with Ultrafast Simulations
Chieh-An Lin (University of Edinburgh)



Camelus is a fast weak lensing peak count modeling in C. It provides a prediction on peak counts from input cosmological parameters.

Here is the summary of the algorithm:

  • Sample halos from a mass function
  • Assign density profiles, randomize their positions
  • Compute the projected mass, add noise
  • Make maps and create peak catalogues

For a more detailed description, please take a look at Lin & Kilbinger (2015a).


Please check the GitHub page of Camelus.


The following softwares are required:


Current release: Camelus v1.31

New features in v1.31 - Mar 22, 2016:

  • Made installation more friendly by removing the dependency on cfitsio and mpi
  • Added the routine for computing 1-halo & 2-halo terms of the convergence profile
  • Flexible parameter space for PMC ABC
  • Remove files: FITSFunctions.c/.h

New features in v1.3 - Dec 09, 2015:

  • New files: constraint.c/.h
  • Allowed multiscale peaks in one data vector
  • Allowed a data matrix from several realizations
  • Used the local galaxy density as the noise level in the S/N
  • Increased the parameter dimension for PMC ABC
  • Changed the summary statistic options for PMC ABC

New features in v1.2 - Apr 06, 2015:

  • Improved the computation speed by a factor of 6~7
  • Converted the halo array structure into a binned structure, called "halo_map"
  • Converted the galaxy tree structure into a binned structure, called "gal_map"
  • Added the population Monte Carlo approximate Monte Carlo (PMC ABC) algorithm

New features in v1.1 - Jan 19, 2015:

  • Fixed the bug from calculating halo radii

New features in v1.0 - Oct 24, 2014:

  • Fast weak lensing peak count modeling


Contact information


Please feel free to send questions, feedback and bug reports to calin AT roe DOT ac DOT uk.

Last updated Jun 26, 2015.