European Space Astronomy Centre (ESAC) Villafranca del Castillo, MADRID (SPAIN) Jesús Salgado SLAP Implementations May 2007, Beijing, China Simple Line Access Protocol (SLAP) v0.6 Current Status Jesús J. Salgado* on behalf of the specification authors * ESA/VO - European Space Astronomy Centre (ESAC)

European Space Astronomy Centre (ESAC) Villafranca del Castillo, MADRID (SPAIN) Jesús Salgado SLAP Implementations May 2007, Beijing, China SLAP for uncorrected lines (I)  There is a need to include support in the SLAP specification for services that includes uncorrected lines  One uncorrected line has the following properties: It belongs to an observational line database, i.e., If a service is able to provide both corrected and uncorrected lines, the service could be registered as soon as a default call to the service only return the corrected lines as output. it contains a value observed Wavelength (ldm:Line.observedWavelength) The wavelength in vacuum has not been calculated yet. There is not a final value for (ldm:Line.wavelength). Raw data and most of pre-processed data is in this status  The wavelength correction does not imply necessarily an identification

European Space Astronomy Centre (ESAC) Villafranca del Castillo, MADRID (SPAIN) Jesús Salgado SLAP Implementations May 2007, Beijing, China SLAP for uncorrected lines (II) o CORRECTION_STATUS This parameter would constraint the search to lines with a assigned wavelength in vacuum value. That implies for observational line databases the correction of the observed central wavelength from environmental/astrophysical effects. “UNCORRECTED” and “CORRECTED” Default value CORRECTED. If a service is able to provide both corrected and uncorrected lines, the service could be registered as soon as a default call to the service only return the corrected lines as output. oIDENTIFICATION_STATUS This parameter would constraint the search to lines with a certain level of identification. “UNIDENTIFIED”, “IDENTIFICATION_UNCERTAIN”, “IDENTIFICATION_PROVISIONAL” and “IDENTIFIED”

European Space Astronomy Centre (ESAC) Villafranca del Castillo, MADRID (SPAIN) Jesús Salgado SLAP Implementations May 2007, Beijing, China SLAP for uncorrected lines (III) o Exactly one field MAY have utype=”ldm:Line.correctionStatus”, with datatype="char" and ucd=“em.wl.central;meta.id.cross", describing if the “ldm:Line.wavelength” has been calculated. Possible values: “Uncorrected” and “Corrected”  Please note that for uncorrected lines the compulsory field with utype=”ldm:Line.wavelength” (corrected wavelength in vacuum) will contain either the observed wavelength for “Uncorrected” or a provisional assignment value. o Exactly one field MAY have utype=”ldm:Line.identificationStatus”, with datatype="char" and ucd=“em.line;meta.id.cross", describing the identification status of the line. Possible values: “Unidentified”, “Identification uncertain”, “Identification provisional”, “Identified”

European Space Astronomy Centre (ESAC) Villafranca del Castillo, MADRID (SPAIN) Jesús Salgado SLAP Implementations May 2007, Beijing, China SLAP support for Observational services  Once we have given support for observational line databases for the level of line correction/identification, it was necessary to include support for 4- dimensional physical parameter space constraints  POS, SIZE and TIME included as non-compulsory parameters. Notation taken from SSAP v1.0 (except reference frame) (degrees ICRS)  The following optional output fields are added in the specification: Char:SpatialAxis.Coverage.Location.Value Char:TimeAxis.Coverage.Bounds.Start Char:TimeAxis.Coverage.Bounds.End  Using both the correction/identification and the 4-D constraints, support for observational line databases (like ALMA) should be covered

European Space Astronomy Centre (ESAC) Villafranca del Castillo, MADRID (SPAIN) Jesús Salgado SLAP Implementations May 2007, Beijing, China SLAP issues to be solved  Before to go to PR, some issues should be solved: Current version of the protocol make use of the FORMAT=METADATA paradigm. As it could be seen during last “Spectroscopy and VO Workshop” held in ESAC, the need of a capabilities discovery process is needed for scientific usage. We will update the document accordingly with the discussions taken during this interop SOLVED! Current plain output is not enough for some scientific use cases. In particular, the number of quantum numbers to characterize a quantum level depends of the level, so that means the number of cells per record of the table is not fixed. Extension mechanism needed Use of uTypes in data models should be clarified (see presentation/debate in Data Model group). That affects the Atomic and Molecular Line data model and, as a consequence, the protocol

European Space Astronomy Centre (ESAC) Villafranca del Castillo, MADRID (SPAIN) Jesús Salgado SLAP Implementations May 2007, Beijing, China SLAP extension needs (I)  ldm:Line.initialLevel.id, ldm:Line.finalLevel.id in main results table  1 J 2 …………………………. 

European Space Astronomy Centre (ESAC) Villafranca del Castillo, MADRID (SPAIN) Jesús Salgado SLAP Implementations May 2007, Beijing, China SLAP extension needs (II)  Current DAL protocols are based in VOTable. Results are showed in the main results table.  Presently a CDS-ESAVO proposal is the only reference to a standard way to include extension mechanisms in DAL protocols  For some science cases, this is also need for SLAP, e.g., In SLAP, start and final levels for the origin of a line are defined in the main result table in a String way. To include better metadata for automatic use, the quantum numbers that define the level should be given. The number of necessary Quantum numbers to define a level is not fixed, so a fix length tabular table is not the way to represent them Secondary resource that includes a set of tables could be a solution, but this extension mechanism is not standard and it is quite ad-hoc

European Space Astronomy Centre (ESAC) Villafranca del Castillo, MADRID (SPAIN) Jesús Salgado SLAP Implementations May 2007, Beijing, China SLAP fields in different units  To create a uniform access to different data we were forced to select a system of units. In this particular case, we decided to use the SI  However, as a transformation is needed and the risk to loose precision exists it has been suggested to duplicate some of the output information in different units: the original and the one imposed by the protocol Energy levels in Joules (typical unit cm-1) Wavelength versus frequency  This is not a SLAP problem but a general one.

European Space Astronomy Centre (ESAC) Villafranca del Castillo, MADRID (SPAIN) Jesús Salgado SLAP Implementations May 2007, Beijing, China Conclusions  Support to observational line data bases has been added  Some open issues to be clarified during this interop  If no major changes to be implemented in the document, the protocol specification could be updated to create WD 1.0 and can start the process to PR at the end of this interop meeting