SSA
xs
ssap
XML Schema used to describe the capabilities of a service instance
conforming to the Simple Spectral Access (SSA) protocol.
The capabilities of an SSA service implementation.
The category indicating the level to which
this instance complies with the SSA standard.
Allowed values are "query", "minimal", and "full".
See definitions of allowed values for details.
The category specifying where the data originally
came from.
Allowed values are "survey", "pointed", "custom",
"theory", "artificial"
The category that describes the process used to
produce the dataset.
Typically this describes only the processing
performed by the data service, but it could
describe some additional earlier processing as
well, e.g., if data is partially precomputed.
Allowed values are "archival", "cutout", "filtered",
"mosaic", "projection", "spectralExtraction",
"catalogExtraction"
Identifiers of spatial reference frames that can be used
in the POS parameter. The identifiers must be taken
from the vocabulary http://www.ivoa.net/rdf/refframe.
At least one recognized value must be listed
when the service supports POS.
With SSA v1.1, ICRS must be supported in that
case; thus,
this list must include at least this value.
The largest search radius, in degrees, that will be
accepted by the service without returning an error
condition. Not providing this element or
specifying a value of 180 indicates that there
is no restriction.
Not providing a value is the prefered way to indicate
that there is no restriction.
The hard limit on the largest number of records that
the query operation will return in a single response.
Not providing this value means that there is no
effective limit.
This does not refer to the total number of spectra in
the archive but rather maximum number of records the
service is capable of returning. A limit that is
greater than the number of spectra available in the
archive is equivalent to their being no effective
limit. (See RM, Hanisch 2007.)
The largest number of records that the service will
return when the MAXREC parameter not specified
in the query input. Not providing a value means
that the hard limit implied by maxRecords will be
the default limit.
The largest aperture that can be supported upon
request via the APERTURE input parameter by a
service that supports the spectral extraction
creation method. A value of 180 or not providing
a value means there is no theoretical limit.
Not providing a value is the preferred way to
indicate that there is no limit.
The maximum spectrum file size in bytes that will
be returned. Not providing
a value indicates that there is no effective limit
the size of files that can be returned.
This is primarily relevant when spectra are created
on the fly (see creationType). If the service
provides access to static spectra, this should only
be specified if there are spectra in the archive that
can be searched for but not returned because they are
too big.
a set of query parameters that is expected to
produce at least one matched record which can be
used to test the service.
The allowed values for indicating the level at which a
service instance complies with the SSA standard.
The service supports all of the capabilities and features
of the SSA protocol identified as "must" in the
specification, except that it does not support returning
data in at least one SSA-compliant format.
This level represents the lowest level of compliance.
The service supports all of the capabilities and features
of the SSA protocol identified as "must" in the
specification.
In brief, this includes:
* implementing the GET interface,
* support the parameters POS, SIZE, TOME, BAND, and
FORMAT
* includes all mandatory metadata fields in query
response
* supports getData method retrieval in at least one
SSA-compliant format
* supports the "FORMAT=METADATA" metadata query.
This level represents the middle level of compliance.
The service supports all of the capabilities and features
of the SSA protocol identified as "must" or "should" in the
specification.
This level represents the highest level of compliance.
The defined categories that specify where the spectral data
originally came from.
A survey dataset, which typically covers some region of
observational parameter space in a uniform fashion, with
as complete as possible coverage in the region of parameter
space observed.
A pointed observation of a particular astronomical object
or field.
Typically, these are instrumental observations taken as
part of some PI observing program. The data quality and
characteristics may be variable, but the observations of
a particular object or field may be more extensive than
for a survey.
Data which has been custom processed, e.g., as part of
a specific research project.
Theory data, or any data generated from a theoretical
model, for example a synthetic spectrum.
Artificial or simulated data.
This is similar to theory data but need not be based on
a physical model, and is often used for testing purposes.
The entire archival or project dataset is returned.
Transformations such as metadata or data model mediation
or format conversions may take place, but the content of
the dataset is not substantially modified (e.g., all the
data is returned and the sample values are not modified).
The dataset is subsetted in some region of parameter
space to produce a subset dataset. Sample values are not
modified, e.g., cutouts could be recombined to reconstitute
the original dataset.
The data is filtered in some fashion to exclude portions
of the dataset, e.g., passing only data in selected regions
along a measurement axis, or processing the data in a way
which recomputes the sample values, e.g., due to
interpolation or flux transformation.
Filtering is often
combined with other forms of processing, e.g., projection.
Data from multiple non- or partially-overlapping datasets
are combined to produce a new dataset.
Data is geometrically warped or dimensionally reduced by
projecting through a multidimensional dataset.
Extraction of a spectrum from another dataset, e.g.,
extraction of a spectrum from a spectral data cube
through a simulated aperture.
Extraction of a catalog of some form from another dataset,
e.g., extraction of a source catalog from an image, or
extraction of a line list catalog from a spectrum (not
valid for a SSA service).
A query to be sent to the service
the center position the search cone given in
decimal degrees.
the size of the search radius.
Fully specified test query formatted as an URL
argument list in the syntax specified by the SSA standard.
The list must exclude the REQUEST argument which is
assumed to be set to "queryData".
This value must be in the form of name=value
pairs delimited with ampersands (&). A query
may then be formed by appending to the base URL the
request argument, "REQUEST=queryData&", followed
by the contents of this element.
a position in the sky to search.
The longitude (e.g. Right Ascension) of the center of the
search position in decimal degrees.
The latitude (e.g. Declination) of the center of the
search position in decimal degrees.
the coordinate system reference frame name indicating
the frame to assume for the given position. If not
provided, ICRS is assumed.