MANGO 1.0: Proposed Recommendation: Request for Comments

There is a paradox in the VO world: source data which represent the basic building blocks of astronomers’ work, is not modelled. This paradox can be explained by the fact that the observation of source objects is multifaceted.
In a general way, the way features for source data are described and organised depends on the targeted science case.Principal investigators and archive designers set up the data profile and structure it according to this goal which varies from one project to another. Therefore this diversity cannot be served by a single static data model describing a source item for all possible cases.
Having a global source model would lead to a very complex solution not usable in practice.
This standard proposes to overcome this paradox and presents a template model gathering independent components from VO existing models embedded on demand in a container. MANGO is not designed to describe what a source is but to help clients to discover and to understand the quantities available for a particular source instance.

VOtable data mapped on MANGO with Mivot annotations can be consumed quantity par quantity instead of column per column. The way complex quantities are built is described by MANGO but no longer by the clients.

The main purpose of MANGO is to add an upper description level to the tabular data of query responses. MANGO is not designed to replace the meta-data already present in query responses,
Uses-cases have been collected since 2019 from representatives of various astronomical missions, archive designers and tools developers. These open contributions gave a good picture of the needs but we do not pretend that everything will be supported by this first version.

Latest version of IVOASTANDARD can be found at:

• URL link to the document

Reference Interoperable Implementations

The project contains 4 static files, located in PROJECT_HOME/implementations, that cover most of the model features (see coverage table). IN additio to this, we have 2 services (Vizier, XMM) providing annotated data.

The term "reference implementation" has never been clearly defined in the context of a model. In the case of MANGO, whose purpose is to restore complex quantities from tabular data, we provide static or dynamic VOtables, whose data are mapped onto MANGO using the Mivot schema. Additionally, we consider the Pyvo Mivot API to be another type of implementation.

Static Files

4 references files implementing most of the model features are provided within the implementations folder in the Git repository. The detail of the covered properties is givel by this table.

• xtapdb:TAP query response on the 4XMMdr14 slim catalog. The VOTable has been annotated on the flight by the server.
  A link binding the postion with a quality flag has been added by hand.

  • file: xtapdb.xml
  • service: https://xcatdb.unistra.fr/xtapdb
  • query: SELECT TOP1 * FROM "public".mergedentry
  • format: application/x-votable+xml;content=mivot

• Gaia:Vizier query response on the GAIA DR3 catalog. The VOTable has been annotated on by hand with the Pyvo MIVOT API.

  • file: gaia_with_mivot.xml
  • service: https://vizier.cds.unistra.fr/viz-bin/votable
  • query: see the mango:origin.QueryOrigin instance

• datalink:Query on an Obscore table made to exercise the mapping on both Footprint and Datalink classes. The VOTable has been annotated on by hand on the project purpose.

  • file: datalink.xml
  • service: https://ws.cadc-ccda.hia-iha.nrc-cnrc.gc.ca/argus
  • query: SELECT TOP 1 ivoa.ObsCore.obs_id,ivoa.ObsCore.s_region,ivoa.ObsCore.access_url FROM ivoa.ObsCore

• vizier_cs_I_239:Cone search response on the I/239 Vizier table. The VOTable has been annotated on the flight by the server.

  • file: vizier_cs_I_239.xml
  • service: https://cds/viz-bin/conesearch/V1.5/I/239/hip_main
  • query: RA=0&DEC=0&SR=0.5

Services

There are two services in operation and serving data mapped on MANGO.

XTapDB (HE Data and Photometry)

A TAP service serving XMM catalogue (https://xcatdb.unistra.fr/xtapdb/) data (table mergedentry) has been deployed.

This service demonstrates the ability of MANGO to properly describe the following quantities

• Coordinate systems (space, time imported from Coords DM)
• Position at a given epoch
• Photometric filters and calibration (imported from Phot DM)
• Fluxes and hardness ratio
• Quality flags

The service can be connected with Taphandle or by using curl (or any other client enable to set a specific format)):

• url: https://xcatdb.unistra.fr/xtapdb/sync?LANG=ADQL&REQUEST=doQuery&QUERY=[QUERY]&FORMAT=application%2Fx-votable%2Bxml%3Bcontent%3Dmivot
• query: SELECT TOP1 * FROM "public".mergedentry
• format: application/x-votable+xml;content=mivot
• example: copy this URL in your clipboard.

Vizier Endpoints

There are 2 Vizier services returning VOtable partially mapped on the EpochPosition MANGO property.

• ConseSearch: Vizier deployed a cone search service that returns VOtable partially mapped on MANGO
  • URL: https://vizier.cds.unistra.fr/viz-bin/conesearch/V1.5/TABLE_ID
  • Example curl "https://vizier.cds.unistra.fr/viz-bin/conesearch/V1.5/I/329/urat1?RA=52.26708&DEC=59.94027&SR=0.05"
• ASU: proprietary URL based protocol to query catalogs.
  • URL: https://vizier.cds.unistra.fr/viz-bin/votable/V1.5?-source=TABLE_ID&-out.max=10
  • Example: curl https://vizier.cds.unistra.fr/viz-bin/votable/V1.5?-so urce=I/239/hip_main&-out.max=10

Python API

An important new module is being added to Pyvo. This module's purpose is to write and read Mivot annotations, with a particular focus on MANGO (see the doc).

• Reader (since Pyvo 1.6):
  • Mivot annotations are rendered as dynamic Python objects that obey the model structure. This allows data to be explored through the model view.
  • If the data id mapped onto the EpochPosition property, this API can automatically extract SkyCoord instance.
• Generic writer (since Pyvo 1.6):
  • Allows to build Mivot annotation element per element (attribute, instance, collection...). This API has been made for developpers to build mode user-friendly functionalities.
• Mango writer (to be released with PyVO1.8)
  • Write coordinate frames (space, time ang photmétric calibration) that are part of Mago instances
  • Map data on EpochPosition, Brightness and Color properties. This is faciltated by a meta-data analizer included in the code.

Implementations Validator

VOTable whose data are mapped onto MANGO can be validated with mivot-validator:

• Package on Pypi
• Doc on readthedocs

The validator operates at 3 levels

• Validation against the VOTable schema
• Validation against the Mivot schema
• Validation of the annoatation agans the models they refer to

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