ESO SIA&SSA Hands-on

Publishing combined image- and spectral-data packages:

ESO has developed tools for publishing images and spectra compliant with SIAP and SSAP Virtual Observatory standards. In this exercise data from the Great Observatories Origin Deep Survey (GOODS) are used: Near infrared images (ISAAC) as wells as multi-object, optical to NIR spectra (FORS2) in the Chandra Deep Field South (CDFS). Download the step by step instructions to be able to reproduce the exercise


SIAP and SSAP are members of an integrated family of data access interfaces altogether comprising the Data Access Layer (DAL) of the IVOA.

SIAP definines an uniform interface for retrieving image data from a variety of astronomical image repositories. A query defining a rectangular region on the CAR frame is used to query for candidate images. The service returns a list of candidate images formatted as a VOTable. For each candidate image an access reference URL may be used to retrieve the image.

SSAP defines an uniform interface to remotely discover and access one dimensional spectra. SSA is based on a more general data model capable of describing most tabular spectrophotometric data, including time series and spectral energy distributions (SEDs) as well as 1-D spectra. Defines spatial (cone region), temporal, spectral and format queries.


  1. Software Installation
  2. Metadata Extraction and Ingestion Process
    • Database setup
    • Mapping editor
    • MEx
  3. Access the data
    • Query the services

1. Software installation

Base components for this workshop

Note that you do not need to install Java JDK 1.5 for this exercise.

Get the ESO data, components and tools specific to this workflow

2. Metadata Extraction and Ingestion Process

  • Database setup
    • create SQL tables
    • catalogue the files according to their type and internal FITS structure.
  • Mapping editor
    • get a sample FITS file header per data type
    • define mappings between FITS keywords and IVOA model metadata parameters
    • test mappings against sample FITS file headers

Try the ESO stand-alone mapping editor:

You can check the ESO guidelines to publish data in VO-compliant way:

The minimum set of information ('data items') requested for image data:

The minimum set of information ('data items') requested for spectral data:

  • MEx
    • ingest FITS into database

3. Access the data

-- MarSierra - 08 Jan 2008

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Topic revision: r13 - 25 Jan 2008 - MarSierra
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