Jean-Marie Mariotti Center

The JMMC is actively pursuing research and developement on several subjects related to interferometric observations and data processing, through specialized working groups:

Astronomical Software to PRepare Observations (ASPRO)

- G. Duvert (IPAG), Principal Investigator
- JC. Augereau, JP. Berger, L. Bourgès, F. Henault, JB. Le Bouquin, F. Malbet, G. Mella, JL. Monin, K. Perraut (IPAG)
- P. Kervella (OBSPM-LESIA)

- Beta testers: J. Kluska (University of Exeter)
- Past scientist members: G. Duchêne, H.Beust, D. Mourard

This group is the science support for the JMMC's observation preparation software ASPRO, whose documentation can be found in the ASPRO section. This group has strong connections with the Calibrators Group (see below), as calibrators are pivotal for interferometric observations, and ASPRO can be used as an interface for the JMMC's SearchCal tool.

ASPRO is an all purpose interferometric observing preparation tool, with special support for the VLTI and its instruments, but can help prepare observations on other interferometers (GI2T, CHARA, IOTA/FLUOR, PTI, etc..) as well[*]. It is a client-server web service declined in three 'flavors': one is dedicated to the preparation of observations with the AMBER intrument of the VLTI, and is updated every 6 month to match closely the current status of the instrument, interferometer limitations and other observing parameters, as described in the ESO "Call for Proposal" published each semester. A second 'flavor' does the same for the MIDI instrument. ASPRO can aso be used with a more general user interface giving access to all its possibilities, to e.g., test a set of baselines not yet offered by ESO.

ASPRO does it job by simulating in a comprehensive manner the actual observations and computing the interferometric observables and their expected uncertainties. It permits to use models of science objects, either simple geometrical models or user-defined models, show the observability of these objects, model their observation and the expected sensitivity of the instruments, retrofit the model in the simulated data to assess whether the science requirements will be met by the actual observations. Asking for ASPRO 'approved' observations is an asset in ESO proposal preparation.

The reader is invited to test ASPRO on its dedicated page. Regular users should apply for a local repository to store ans retrieve their personal data (use models, list of sources, preferences, etc...)

[*] If you are interested in having ASPRO supporting your interferometer, contact us at JMMC user support.

Catalogue of calibration sources

- A. Chelli (LAGRANGE), Principal investigator
- D. Bonneau, P. Cruzalebes (LAGRANGE)
- H. Beust, L. Bourgès, X. Delfosse, G. Duvert, J.-B. Le Bouquin, G. Mella (IPAG)

- Past engineer members: J-M. Clausse (2002-2005), S. Cêtre (2003-2005), S. Lafrasse(2003-2014), Y. Vanderschueren (2004-2005), G. Zins (2003-2007)
- Past scientist members: P. Bério (2001-2002), P. Bordé (2001-2003), O. Chesneau (2014†) , X. Haubois (2006-2007), A. Mérand (2004-2005), D. Mourard (2001-2012), R. Pétrov (2002-2007)

Optical long baseline interferometry allows determining the morphology of astronomical sources at high angular resolution from the complex visibility of the source provided by the measurement of the contrast and phase of the interference fringes. Still, the raw fringe visibility must be calibrated to take into account atmospheric and instrumental effects and the selection of suitable calibration stars is crucial to reach the ultimate precision of the long baseline interferometers. The JMMC calibrators group have produce a software tool (SearchCal) to assist the astronomer in the search and the selection of calibration stars for interferometric observations in the visible (i.e. V band) or the near infrared (i.e. J, H, K bands).

The structure of the SearchCal tool has been directed to create a dynamical catalogue of stars in the calibrator field defined around the science object using astrophysical requirements. SearchCal has been designed as an on-line service which uses a method of the "virtual observatory" type to extract all relevant astronomical parameters (i.e. astrometry, spectral type, visible and IR magnitudes, variability and multiplicity flags) from a set of stellar catalogues available in the data base VizieR at CDS. For each possible calibrator, the expected visibility at the time of the observation is estimated using the information available in the astronomical databases. The current version of SearchCal ("bright object" case, magnitudes V<12 and K<5) is integrated into ASPRO the interferometric observing preparation software issued by the JMMC.

To follow the gain in sensitivity expected with the interferometric instruments (in particular on the VLTI) a "faint objects" case of SearchCal (magnitudes K>5 or V>12) was developed with a limiting magnitude only bounded by that of the photometric catalogues of the CDS. The new version of SearchCal will be soon available as web service with display in the environment of a Virtual Observatory portal.

Under product of the SearchCal tool is the development of catalogues of calibrateurs for the targets of observing programs which will be carried out with instrument PRIMA of the VLTI. Collaboration is in progress between the JMMC calibrator group and the ESO science staff to create an improved calibrator tool for the current and 2nd generation instruments of the VLTI.

Instrument data reduction software

- J.-B. Le Bouquin (IPAG), Principal Investigator
- G.Duvert, F. Malbet (IPAG)
- A. Chelli, F. Millour (LAGRANGE)

- Beta testers: O. Absil, J.-B. Berger, A. Merand
- Past members: E. Altariba, M. Benisty, A. Domiciano, R. Petrov, E. Tatulli, G. Zins

The group develops and maintains the pipeline of the Astronomical Multi-BEam Recombiner (AMBER), near-infrared instrument installed at the focus of the Very Large Telescope Interferometer (VLTI). This includes the user interface, written as a plugin in yorick, the code procedures in C, the user documentation, and the testing of innovative algorithms. After several years of development and optimisation, the pipeline is now stable in version 3, accessible on the AMBER data processing page at JMMC.

Since 2014, the group also distributes the pipeline of the PIONIER instrument from VLTI, accessible on the dedicated page at JMMC. Automatically processed data for this instrument are made available in the OiDb database.

Members of the group are also involved in the pipeline of GRAVITY and MATISSE instruments, although not formally endorsed by the JMMC but by the respective consortia. This triggers fruitful sharing of expertises with all groups of JMMC.

Model fitting -

- I. Tallon-Bosc (CRAL), Principal investigator
- M. Tallon (CRAL)
- H. Beust, L. Bourgès, G. Duvert, G. Mella (IPAG)
- A. Domiciano de Souza, M. Vannier (OCA-LAGRANGE)

- Beta testers: N. Nardetto, J.-B. Le Bouquin
- Past members: C.Béchet, P. Berlioz-Arthaud (2016†) , O. Chesneau (2014†), S.Lafrasse, F. Millour, E.Thiébaut, G.Zins, M. Chadid, A. Chelli, D.Mourard G. Perrin, P. Stee, R. Petrov

The aim of the "Model fitting" working group is to develop a software for fitting models on data obtained from various stellar optical interferometers, existing or coming. Those data must be written in the OI Exchange Format.

This software, named LITpro (for Lyons Interferometric Tool prototype) written in Yorick, provides for modeling the object, a set of elementary geometrical and center-to-limb darkening functions, all combinable together. It is also designed to make very easy the implementation of more specific models with their own parameters, to be able to use models closer to astrophysical considerations. LITpro only requires the modeling functions to compute the Fourier transform of the object at given spatial frequencies, and wavelengths and time if needed. From this, it computes all the necessary quantities as needed (e.g. visibilities, spectral energy distribution, partial derivatives of the model, map of the object model). The fitting engine, especially designed for this kind of optimization, is based on a modified Levenberg-Marquardt algorithm. It includes a Trust Region Method, minimizing a heterogeneous non-linear and non-convex criterion and allows the user to set boundaries on free parameters. From a robust local minimization algorithm and a starting points strategy, a global optimization solution is effectively achieved. Tools have been developed to help users to find the global minimum. LITpro is also designed for performing fitting on heterogeneous data, like for example interferometric data and data of spectral energy distribution.

Since LITpro has to be used easily, and largely accessible, it must be seen as a desktop application: a GUI has then been built, using a Java platform, like other graphical applications developed by the JMMC. To provide specific model-fitting computation inside the Java GUI, the scientific code is not rewritten in Java but is delegated to the existing LITpro "expert" layer. This layer has been indeed deployed on a dedicated server, to provide Model-Fitting capabilities through a webservice across the Internet.

The Model Fitting group comes from a restructuration in February 2004 of the previous "Models group". It simultaneously became a Working Package (WP2.3) of the Joint Research Activity 4 (JRA4) "Integrating interferometry into mainstream astronomy". In the JRA4 context, the group has to furnish some basic documents until the public software itself, and worked in coordination with the JRA4 Work Package "Common Software" (WP2.2). Since 2007, it works through another architecture : an "expert" layer (the fitting software itself LITpro) under a Java GUI. A first public delivery of the software is foreseen for Autumn 2009.

Image reconstruction -

- Eric Thiebaut (CRAL), Principal investigator
- J. Leger, F. Soulez (CRAL)
- L. Mugnier (ONERA)
- L. Bourgès, G. Duvert, G. Mella (IPAG)
- A. Domiciano, A. Ferrari, M. Vannier, A. Schutz (OCA-LAGRANGE)

- Beta testers: S. Meimon
- Past members: E. Altariba

The objective of this group is to develop an image reconstruction algorithm aimed at the processing of interferometric data. This algorithm is specially tuned for the case of optical interferometry, in particular: small number of telescopes (from 3 or 4), no phase reference and specific noise statistics. This group participated into the work package "Image Rebuilding" (WP2.5) of the JRA4 from 2004 to 2008. First versions of the softwares have been delivered.

Currently, two prototypes have been developed and compared to other algorithms during the Interferometric Image Beauty Contest.WISARD was mainly developed by ONERA and MiRA was developed at CRAL.Both prototypes take into account phase closures data, power spectrum data and their statistics to rebuild an image under the control of some prior which plays the role of the required regularization. The algorithms are in the course of finalization to allow their use by non-experts without limiting their capabilities.

Optical Interferometry Database (OiDB)

- Scientific Leader : Xavier Haubois
- M. Benisty, L. Bourges, G. Duvert, J.-B. Le Bouquin, G. Mella (IPAG)
- P. Berio, A. Chelli, D. Mourard, N. Nardetto (LAGRANGE)
- X. Haubois, S. Lacour (OBSPM-LESIA)
- Johan Olofsson (Universidad de Valparaíso)
- Observer: T. Paumard (OBSPM-LESIA), JM. Clausse (LAGRANGE)
- Beta testers:
- Past members: P. Bernaud

The Virtual Observatory (VO) is opening up new ways of exploiting the huge amount of data provided by the ever-growing number of ground-based and space facilities. Specially created to develop softwares for the exploitation of interferometric facilities, the Jean Marie Mariotti Center (Aspro, LITpro, amdlib, SearchCal) is working on VO tools to increase the diffusion and operability of interferometric data. As a first part of this project, we are developing an OIFITS archive containing or at least describing reduced interferometric observations (first-version OIFITS) obtained with a wide range of interferometric instruments. The goal is to make this database as complete as possible and easy to use for non-specialists.
Get more detail on the OiDB realization.

Technical staff and software development

- Technical Director: L. Bourgès (OSUG), Coordination Center Leader : G. Mella (OSUG)
- Past members: E. Altariba, P. Bernaud, S. Cêtre, J-M. Clausse, L. Gluck, V. Jammet, C. Kemps, P. Kervella (webmaster),S. Lafrasse, Y. Vanderschueren, G. Zins
- Past trainees members: B. Colucci, J-P Gros, N. Hofmann, S. Prette, T. Stein, E. Taillifet, S. Vedel

This group aims at developing softwares and managing services distributed by the JMMC. Technical staff is highly coupled to scientists through the whole life of JMMC projects (from project specification to code contribution and support). The JMMC has defined tools and rules to improve quality of software developments. The JMMC considers Virtual Observatory as a data provider but also as a powerfull technical framework.

Most of the JMMC softwares and services are distributed over the Internet. Our website management is handled by the webmaster, whom ensures best content to our users. Servers maintenance ((installation, maintenance, network management, security, databases, user authentification, download mechinisms, mailing lists...) is done by the JMMC staff with support from OSUG and Grenoble University system administrators.

The technical staff also responds to technical support with JMMC members and users in collaboration with the jmmc-user-support team.