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Simple Spectral Access Protocol
Version 1.1

IVOA Proposed Recommendation 18 October 2011

Interest/Working Group:
http://www.ivoa.net/twiki/bin/view/IVOA/IvoaDAL
Author(s):
Dou Tody, Markus Dolensky, Jonathan McDowell, Francois Bonnarel, Tamas Budavari, Ivo Busko, Alberto Micol, Pedro Osuna, Jesus Salgado, Petr Skoda, Randy Thompson, Frank Valdes
Editor(s):
Doug Tody

Abstract

The Simple Spectral Access (SSA) Protocol (SSAP) defines a uniform interface to remotely discover and access one dimensional spectra. SSA is a member of an integrated family of data access interfaces altogether comprising the Data Access Layer (DAL) of the IVOA. 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; however the scope of the SSA interface as specified in this document is limited to simple 1-D spectra, including simple aggregations of 1-D spectra. The form of the SSA interface is simple: clients first query the global resource registry to find services of interest and then issue a data discovery query to selected services to determine what relevant data is available from each service; the candidate datasets available are described uniformly in a VOTable format document which is returned in response to the query. Finally, the client may retrieve selected datasets for analysis. Spectrum datasets returned by an SSA spectrum service may be either precomputed, archival datasets, or they may be virtual data which is computed on the fly to respond to a client request. Spectrum datasets may conform to a standard data model defined by SSA, or may be native spectra with custom project-defined content. Spectra may be returned in any of a number of standard data formats. Spectral data is generally stored externally to the VO in a format specific to each spectral data collection; currently there is no standard way to represent astronomical spectra, and virtually every project does it differently. Hence spectra may be actively mediated to the standard SSA-defined data model at access time by the service, so that client analysis programs do not have to be familiar with the idiosyncratic details of each data collection to be accessed.

Status of this document

This is an IVOA Working Draft for review by IVOA members and other interested parties.
It is a draft document and may be updated, replaced, or obsoleted by other documents at any time.It is inappropriate to use IVOA Working Drafts as reference materials or to cite them as other than "work in progress".



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