Description

This topic is dedicated to the ASPRO data model describing both the interferometer (stations, instruments, configuration) and an observation using an interferometer configuration with user parameters.
This model is related to meta data describing how the observation is done and do not describe the data itself. Optical interfometry products (visibilities, phase closures) use the OIFits file format but its data model does not describe in depth the interferometer & instrument configurations.

Interferometer

The interferometer is spread in two parts : a description with all possible elements (stations, delay lines, pops, switchyard, instruments ...) and one or more configurations to limit the real possibilities with these elements (instruments with their baselines ...).

Interferometer description

The interferometer description has the following elements :

• observatory position
• list of Telescopes (diameter / adaptiveOptics TBC)
• list of Stations (relative Position / associated Telescope / fixed offset / horizon profile)
• list of channels / beams
• list of delay lines (maximum throw)
• switchyard (fixed delay per [station / delay line] couple)
• pops (fixed delay per [station / pop] couple)
• list of instruments with their modes (wave length range)

Interferometer configurations

For now, interferometer configurations are really useful to model the VLTI restrictions associated to an ESO Call for Proposal Period like the list of allowed baselines per instrument.

The other interferometer have only one configuration listing all possible baselines per instrument.

Observation

The observation is defined by an the observation setting with :

• when : date
• interferometer configuration reference
• instrument reference + selected baseline (station list)
• list of targets (ra, dec, magnitudes ...)
• other parameters : TBC

Data Model Xml Schema

The current data model is written as an XML schema and is provided below :

Current Version : 8 Dec. 2009 :

• AsproOIModel.xsd: Xml schema for the data model

Sample documents

The following documents illustrate two interferometer description for the VLTI and the CHARA interferometers :

• VLTI.xml: VLTI description

• CHARA.xml: CHARA description

Observation / Provenance Data models

The IVOA organisation defines several data models related to astronomical observations to be used in the context of the virtual observatory (VO) :

• The Observation DM is a working draft that provides a domain model for observations and so define common items (target, dataset characterization, provenance & curation)
• The Characterisation DM is an official recommendation that describes the characteristics of the dataset among several axes(spatial, time, spectral)
• The Provenance DM is a work in progress and information can be found in the following documents (thanks to Juan de Dios Santander Vela) : Radio VO Thesis

The Aspro Observation can be seen in the VO context with the following parts :

• Curation : to describe the origin of the observation : DataID (proposal, project, identifier, creator, date of observation)
• Provenance : interferometer and instrument description / Environment (partially as ASPRO observations are instead simulations)
• Characterisation : spatial coordinates, time coverage with integration steps ...

The Provenance seems to be the common part where optical interferometer can be described in the VO context.

Here are several diagrams illustrating the Provenance data model :

• Interferometer case :

• Radio (RADAMS) case :

UCD ?

-- LaurentBourges - 08 Dec 2009