.. _SIRLocationTable: Location Table Product ---------------------- Data product name ================= .. DataProductNameStart LocationTable .. DataProductNameEnd Data product custodian ====================== .. DataProductCustodianStart SIR .. DataProductCustodianEnd Data model tag ============== .. DataModelTagStart R-1.6.6 .. DataModelTagEnd Name of the Schema file ======================= .. NameSchemaStart euc-test-sir-LocationTable.xsd .. NameSchemaEnd Schema documentation tag ======================== .. SchemaDocTagStart No documentation element was found in schema file! Data Model custodian: even minimal information can be helpful .. SchemaDocTagEnd Data product elements ===================== .. DataProductElementsStart Header of type: sys:genericHeader Data of type: sir:genericSirCollection Parameters of type: ppr:genericKeyValueParameters .. DataProductElementsEnd Processing Element(s) creating/using the data product ===================================================== .. PECreatorStart This data product is produced by the SIR_SpectraLocation PE. It is used by SIR_BackgroundSubtraction, SIR_SpectraDecontamination and SIR_SpectraExtraction PEs. .. PECreatorEnd Processing function using the data product ========================================== .. PFUsingStart This is an internal data product. It is used only by SIR-PEs. .. PFUsingEnd Detailed description of the data product ======================================== .. DetailedDescStart The main purpose of the **LocationTable** is to gather information to locate and extract spectra on the detectors. **LocationTable** is an hierarchical organization of **LocationSpectra**, **AstronomicalObjects** and **LocationObjects**. Each object in the field of view produces spectra of different orders. The **LocationSpectrum** describes every spectral trace (of every orders) produced on the detectors. A single spectrum can involve multiple detectors; in this case one **LocationSpectrum** for each detector is created. The **LocationSpectrum** is the atomic component of the **LocationTable**. **LocationSpectra** which refer to the same target are collected into the **LocationObject**. The **LocationObject** contains also the **AstronomicalObject** which describes physical properties of the target. The **LocationTable** data product is the hierarchical collection of **LocationObject** of all available targets. Each one of these objects (**LocationSpectrum**, **LocationObject**, **AstronomicalObject** and **LocationTable**) is serialized as HDF5 `group `_ into the HDF5 `file `_. These 4 objects will be described in details in the next paragraphs. .. _LocationTableGlobal: .. figure:: ./figures/LocationTableGlobal.png : Location Table HDF5 file structure. Location Spectrum group +++++++++++++++++++++++ Due to optical distortions and uncertainty in grism alignment, dispersed spectra are curved and not perfectly aligned with the dispersion direction. Since this curvature changes moving around the the FOV, each spectrum has it own curvature and it own inverse wavelength solution. These 2 properties are different spectrum by spectrum. For this reason the SIR_Pipeline has to produce one **LocationSpectrum** (green box in :numref:`LocationTableGlobal`) for each spectrum in the FOV. The **LocationSpectrum** group contains information about geometry of the spectrum and it is used to locate spectral wavelengths on the detector. This is performed by: #. Setting a lambda reference value * this value is defined by the `attribute `_ *Offset* of the IDSX and IDSY groups. #. Identifying the positions on the detector of this lambda reference value along the cross-dispersion direction * these positions are defined by The *Reference lambda* `dataset `_. This dataset is a n by 2 matrix, each row defines the pixel where the reference lambda is. Number of rows changes object by object according with object size and angle. #. Applying polynomial solutions: along X and Y directions. * the IDSX and IDSY groups contain the *Coeffs* dataset: the polynomial coefficients of the wavelength solution. Each row is a set of polynomial coefficients; the number of rows of this dataset must be identical to the number of rows of the *Reference lambda* dataset. Finally the **LocationSpectrum** contains attributes used to uniquely identify the spectrum: * the target *ID* * the *Order* of the spectrum itself * the *Grism Position*: 0, 90 or 180 * the *Detector* involved by the spectrum * the *Exposure ID* * the *Field ID* .. _AstronomicalObject-label: Astronomical Object group +++++++++++++++++++++++++ The **AstronomicalObject** (yellow box in :numref:`LocationTableGlobal`) gathers the astronomical properties of the target using the attributes: * *Angle* of the object in the sky * *Bulge fraction* of the target * Y-H *Color* * *Dec* and *RA* coordinates * object *ID* * *Major axis* and *Minor axis* of the object * object *Type*; at the moment only star (1) and galaxy (2) are implemented Beside these values the **AstronomicalObject** also contains infrared magnitudes of the objects. The *Magnitudes* `complex type `_ table has 3 columns: * the magnitude *Band* * *Vega* flag: 1 if the magnitude is in the Vega system, 0 if not * the magnitude *Value* Location Object group +++++++++++++++++++++ The **LocationObject** (purple box in :numref:`LocationTableGlobal`) collects together spectra with the same target ID; it combines one **AstronomicalObject** and several **LocationSpectra**. Location Table group ++++++++++++++++++++ The **LocationTable** (cyan box in :numref:`LocationTableGlobal`) data product gathers **LocationObjects** and organizes them according with 2 different criteria: #. In the *Detector_n* groups **LocationObjects** are organized detector by detector (blue box in :numref:`LocationTableHierarchy`). Each **LocationObject** in one of these groups contains only spectra produced on the n-th detector. #. In the *Location Objects* group **LocationObjects** are organized by ID (red box in :numref:`LocationTableHierarchy`). **LocationObject** in this group gathers all spectra in the FOV with the same target ID. .. _LocationTableHierarchy: .. figure:: ./figures/LocationTableHierarchy.png : Different hierarchy in the Location Table. Finally the *Reduction Recipes* group contains one attribute for each input parameter of the SIR_Pipeline task used to create the **LocationTable** itself. .. DetailedDescEnd