21cm Club Meeting 2016 October 25

Merci à tout le monde qui a participé mardi!  Voici un petit compte

le 25 octobre 2016, Salle du Levant, bâtiment Perrault, Observatoire de Paris


Françoise Combes
Jean-Michel Martin
Martin Bucher
Benoît Semelin
Marc Moniez
Ken Ganga
Réza Ansari
Steve Torchinsky

Martin nous a présenté le papier par Masui et al, « Dense magnetized
plasma associated with a FRB », arxiv:1512.00529, 2015 Nature, 528, 523

Nous avons discuté les indications fortes de la nature extragalactique
du FRB (DM, scintillation).

Ensuite, nous avons fait un résumé des projets BAO Intensity Mapping:





En discutant HERA, il a été décidé de faire un résumé des precursors
et pathfinders pour le SKA:

Les 4 precursors: ASKAP, MeerKAT, MWA, HERA


la participation d’ASKAP aux observations suite à la détection de

discussion sur la technologie de « Phased Array Feed », avec mention
du projet APERTIF sur Westerbork (SKA Pathfinder).



première image de MeerKAT (16 paraboles)

Murchison Widefield Array

HERA (mentionné plus haut)

Les 13 Pathfinders, dont 3 sur le site de Nançay:




et les 10 autres:
APERture Tile In Focus (APERTIF), The Netherlands
Arecibo Observatory, Puerto Rico
Allen Telescope Array (ATA), USA
electronic European VLBI Network (eEVN), Europe
Expanded Very Large Array (EVLA), USA
Giant Metrewave Radio Telescope (GMRT), India
Long Wavelength Array (LWA), USA
Parkes Telescope, Australia
SKA Molonglo Prototype (SKAMP), Australia

Fin de la réunion vers 13h et ensuite quelques-uns d’entre nous ont
continué les discussions à La Chope Daguerre, rue Daguerre.

Il a été proposé de faire la prochaine réunion à Nançay avant
mi-décembre.  Un doodle sera bientôt en ligne pour choisir la date.

Steve & Martin

Posted in Non classé | Leave a comment

21cm Club meeting 3 June 2016 at LAL

Today’s meeting is hosted by LAL.  Thanks to Reza for the local organization!

Friday, 3 June 2016, 10.30 in room 101 of LAL.

Initial topic for discussion:
Bull et al, 2015, ApJ, 803, 21


Unfortunately, this meeting was cancelled because of flooding, and strikes.

back to the doodle to choose a new day:

Posted in Non classé | Leave a comment

21cm Club

21cm Club

A discussion group for 21cm Cosmology

first meeting: 26 April 2016 at APC

second meeting: 25 October 2016 at Observatoire de Paris

Posted in Non classé | Leave a comment

21cm Club: 26 April 2016

Date: Thu, 28 Apr 2016 11:03:23
From: Steve Torchinsky <steve.torchinsky@obspm.fr>
To: Club 21cm
Subject: 21cm Club summary and next meeting

Hi Everyone,

Thanks for a very interesting discussion on Tuesday!

The next meeting will be hosted by LAL in the first half of June.
Please fill in the doodle:

Here are a few notes from Tuesday’s meeting:

21cm Cosmology club meeting
26 April 2016 at APC, Paris, 10.30 to ~14.30 (including lunch).

Martin Bucher
Ken Ganga
Reza Ansari
Marc Moniez
Steve Torchinsky
Aurore Savoy-Navarro
George Smoot

HIRAX: Martin Bucher and Ken Ganga

HIRAX is The Hydrogen Intensity and Real-time Analysis eXperiment.  It is a 21cm intensity mapping instrument to be built on the SKA South Africa site.  It will be composed initially of 128 7m dishes, and will later grow to 1024 dishes.  Redshift range 0.8 to 2.5 (400MHz to 800MHz).

Martin is an honorary professor at Universty of Kwazulu-Natal, and both Ken and Martin have an established collaboration with Jonathan Sievers, the PI of HIRAX.

CHIME: (all)

CHIME is the Canadian HI Intensity Mapping Experment.  No French astronomers are currently members of the collaboration.  CHIME is composed of 4 cylindrical reflectors, each of 20m diameter, and 100m diameter length.  The line focus is populated by a number of dipoles, and CHIME is a transit telescope using beamforming to map the sky. The CHIME pathfinder was operational last year, and the full CHIME should start taking data this year.

GBT: (all)

survey correlated with optical survey (Masui et al, 2013, ApJ, 763, L77), and recent « re-cleaning » by Wolz et al (arXiv:1510.05453)

Intensity Mapping with FAST: George Smoot
and by Bigot-Sazy et al arXiv:1511.03006

PAON4 at Nancay and TIANLAI: Reza

PAON4 is a 4 dish array, each of 5m diameter, installed at Nancay. This is a prototype to test the BAOradio electronics which is also a contribution to the TIANLAI dish array in China.  TIANLAI is two separate instruments.  There is an array of cylinders, and a 16 dish array.


The use of Nançay Radio Telescope and the BAORadio electronics to detect 21 cm signal in nearby clusters (A85 ?) On sky characterization of the BAORadio wide band digital backend
Search for H I emission in Abell85, Abell1205 and Abell2440 galaxy clusters:
Ansari et al, 2016, Experiment Astronomy, 41, 117

Map making for transit interferometers , noise power spectrum, sensitivity to temp. brightness.  The first paper submitted to MNRAS, « Sky reconstruction method from transit visibilities application to the PAON-4 & Tianlai Dish Array« 

SKA Mid Frequency Aperture Array: Steve

The dense packed array of antennas is proposed for the second phase of SKA for the frequencies between 450MHz and 1450MHz.  EMBRACE is the prototype in operation at Nancay composed of 4608 Vivaldi antennas. Results and details of the characterization of EMBRACE are published in A&A 2016, 589, A77,

The SKA Phase 2 is currently planned for ~2030.  In the shorter term, a station of around 1000m2 is proposed to be built on the SKA South Africa site, and hopefully will be in operation roughly on the same time scale as SKA Phase 1 (probably around 2022 or so).  The project is called MANTIS.  It’s led by ASTRON, and we are seeking funding.  A first draft proposal has been written, but it’s not clear where to submit a funding proposal.

France is not a member of SKA, and it doesn’t look like we will become members before Phase 2 (not before 5 years from now).


INFIERI is the INtelligent, Fast, Interconnected and Efficient devices for Frontier Exploitation in Research and Industry.

INFIERI is a European Commission FP7 ITN network.  Aurore is the coordinator.  INFIERI focuses on training of Early Career Scientists by funding PhD students, post-docs, and organizing two workshops and a summer school each year.  Projects are related to front-end hardware and software development, including fast data processing and algorithm development in the fields of particle physics, astrophysics, and medical physics.  In astrophysics, the Cerenkov Telescope Array and SKA are the primary instruments for INFIERI.

Discussion continued over lunch.

next meeting at LAL in early June: doodle survey

Steve & Martin

Posted in Non classé | 2 Comments

BAORadio (english)

Mapping cosmic matter distribution  in radio, through the observation of 21 cm radiation of neutral atomic hydrogen is a complementary method to optical surveys to study Large Scale Structures (LSS) and more specifically, the Baryon Acoustic Oscillations (BAO). An R&D program for 21 cm cosmological surveys is being carried out by LAL (CNRS/IN2P3), IRFU (CEA) and several Observatoire de Paris laboratories: GEPI, LESIA and the Nançay radio astronomy observatory (USN). The BAORadio R&D effort is part of an international effort, bringing together scientists from France, USA, Canada and China. The NAOC (National Astronomical Observatories, Chinese Academy of Sciences), Carnegie Mellon University (CMU), University of Wisconsin (UW), Fermilab and CITA are among the institutes contributing currently to the project.

The following sub-projects are currently part of BAORadio in France:

  • Development of a set of electronic modules suited to 21 cm digital interferometry (BAORadio electronic system)
  • Development of the acquisition and processing software suit, including a software correlator (BAORadio / TAcq package)
  • FAN, which is a focal plane phased array receiver system for the Nançay radio telescope (NRT), equipped with the BAORadio electronic and acquisition system
  • PAON, which is a small testbed for dense array interferometers using small (D ~ 5 m) dishes with wide band receivers at Nançay
  • Wide band observations using the NRT and the BAORadio electronic system or the WIBAR receiver system, aiming at the detection of HI in clusters in the redshift range z ~ 0.1-0.2 (Amas@Nançay)


Posted in Non classé | Leave a comment

Liens utiles / Useful links


Project meeting pages on indico:

International partners web pages:

Workshops related to 21cm cosmology & BAO:

  • CRT/BAORadio/Tianlai list of workshops …
Posted in Non classé | Leave a comment

BAORadio (Français)

La cartographie de l’univers en radio, à travers l’observation de la raie à 21 cm de l’hydrogène atomique, constitue une approche complémentaire aux relevés optiques pour l’étude des grandes structures, et des oscillations acoustiques baryoniques (BAO) en particulier. Un programme de recherche et développement est mené par le LAL (CNRS/IN2P3) et l’IRFU (CEA) et l’Observatoire de Paris (la station de Nançay, GEPI, LESIA)  en vue d’un projet de relevé cosmologique à 21 cm avec des partenaires internationaux (Chine, Etats-Unis, Canada …). Nos activités comprennent plusieurs axes:

  • Développement d’une chaîne électronique adaptée à l’interférométrie à 21 cm (électronique BAORadio)
  • Développement des logiciels d’acquisition et de traitement des signaux radio, et d’un corrélateur logiciel (TAcq)
  • FAN, prototype de réseau phasé au foyer du NRT, utilisant l’électronique BAORadio
  • PAON, prototype d’interféromètre à base d’antennes de petites dimensions (D~5m) à Nançay
  • Observations large bande avec le NRT et l’électronique BAORadio (programme Amas@Nançay)
Posted in Non classé | Leave a comment