IVOA SSA Interface

Although the databases of specdb are primarily intended to be accessed on one’s local machines, the repository includes software to add additional meta-data for IVOA compliance and to generate VOTables from a specdb database for standard Simple Spectral Access (SSA) queries.

For the following, we have referred to the Simple Spectral Access Protocal, Version 1.1 document and the IVOA working draft 20110319 of Version 2.0 of the Spectral Data Model (dated 20160928).

Notebooks

Meta Data

See the Private Database documentation for tips on how to add meta data for IVOA compliance.

SSA Interface

The repository includes a simple class SSAInterface which ingests a specdb database and enables standard SSA queries.

Instantiation

Instantiation is straightforward:

from specdb import ssa as spdb_ssa
ssai = spdb_ssa.SSAInterface(igmsp)

querydata

One may perform a standard SSQ querydata using the interface. Currently, only the POS, SIZE, and FORMAT parameters are enabled:

# votable = ssai.querydata(POS, SIZE=, FORMAT=)
votable = ssai.querydata('0.0019,17.7737', SIZE=1e-3)

The method returns a VOTable generated by astropy. See below for a listing of the standard meta parameters.

METADATA

As per SSA protocol, a data query with FORMAT=METADATA:

votable = ssai.querydata(FORMAT='METADATA')

will return the default input and output parameters of the service. The following shows the current implementation.

Referring to the Version 2.0 of the Spectral Data Model, all of the mandatory parameters are included except:

Field	Reason
Char.SpatialAxis.Coverage.Bounds.Extent	The aperture is not always precisely defined or known
Char.TimeAxis.Coverage.Bounds.Extent	The total exposure time has not always been recorded and
	spectra are often the combination of ones acquired over mutiple nights

Also, Target.Name is simply the data group name with the GROUP_ID appended.

specdb SSA METADATA shows the current METADATA response.