OiDbTechnicalSpecs < Jmmc/Software

This topic aims to describe the specification from a technical point of view.

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---+ 1.3 Granularity

The following discussion apply to data extraction from individual OIFits files.

Subgrouping must be done in the following order : target(OI_TARGET), instrument(OI_WAVELENGTH), night (OI_DATA rows) 

---++ Group by targets

The purpose is to identify different targets within an OIFits file or a file set.

---+++ Check and identify a target with Simbad

Function: return id for a target given its description
Inputs: target name (string) and/or coords (ra(deg), dec(deg), equinox(int))
Output: Simbad target identifier

---++++ Definitions

Target identifier (integer): OID (integer) from Simbad resolution if success resolving target

---++++ Function contents

   * if target_name
      * do name resolution with Simbad
         * no result
            * continue
         * single result: check returned coords against given coords
            * no coords: return identifier
            * off coords: raise error
            * within search radius: report difference, return identifier
         * more than one result
            * select result with closest to coords (within search radius)
   * do resolution with coords (and search radius)
      * no result
         * continue
      * single result
         * if name != result.name, report warning
         * return identifier
      * multiple result
         * report warning
         * return closest result
   * return resolution failure

---++++ Use cases

   * invalid coords
   * fancy coords
   * resolution of target name close to coords 
   * target name and coords do not match (big distance)
   * unknown target

---++++ Impact

   * jmcs :
      * manage coords with equinox != 2000
      * resolve target names with simbad (catalog)
   * oiexplorer-core
      * function implemtation

---++++ Notes

   * selection of the search radius for coord resolution
   * associate resolution timestamp to result in case of reprocessing later?
   * any additional information to save from resolution result?


---+++ Identify target

Function: return id for a target given its description
Inputs: target name (string) and or coords (ra(deg), dec(deg), equinox(int))
Output: target identifier

This provides an identifier even if the target is unknown by Simbad.

---++++ Definitions

temporary id: negative integer (no conflict with Simbad ID)
id cache: an association table between name or coords and identifier

---++++ Function contents

   * try resolving with Simbad
      * success
         * return identifier
      * failure
         * search temporary id cache with coords
         * if unknown target
            * create a new temporary id
            * save association of temporary id with coords in cache
         * return id


---+++ Identify targets in a !OIFitsFile

An !OIFits file can contain data for several targets. These targets are represented as rows inside the OI_TARGET table.

There is no guarantee that the targets are correct and unique within the target.

Function: associate ids to targets in a !OIFits file
Inputs: OI_TARGET table (TARGET_ID, RAEP0, DECEP0, EQUINOX columns)

---++++ Definitions

OI_TARGET identifier: derived column with type integer
temporary id: negative integer (to separate from Simbad identifier) associated with coords

---++++ Function contents

   * for each row in table
      * if fancy/incomplete coords
         * return failure
      * run 'identify target'
         * success
            * set derived column with id
         * error
            * search temporary id cache with coords
            * if unknown target
               * create a new temporary id
               * save association temporary id with coords
            * return temporary id

---++++ Use cases

   * invalid coords
   * resolution of target name close to coords 
   * target name and coords does not match (big distance)
   * unknown target
   * set unknown targets

   * fancy coords
   * missing coords
   * missing name
   * duplicated targets in rows

---++++ Impact

   * oitools: add derived columns in OI_TARGET (!TargetUUID + !CatalogIDs)
   * oiexplorer-core: function implementation



---++ Group by instrument mode
Function: retrieve instrument modes %BR%
Inputs: OI_WAVELENGTH tables : INSNAME + EFF_WAVE_min/max + NB_EFF_WAVE + EFF_BAND %BR%
        knowledge instrument_mode database %BR%
Outputs: List of instrument modes


Do not presume that every data are sorted properly in OIFits files when searching for min/max values.

---+++ Use cases
   * same data with epsilon values should retrieve the same instrument mode  (may feed INSNAME aliases)

---+++ Impact
   * oitools : add derived column (InsModeID for each OI_DATA or one per data row?)
   * oiexplorer-core : compute instrument signature (insname, wavelengths, resolution)
   * oidb :
      * use instrument signature to select instrument mode
      * insname aliases, knowledge database (aspro-conf)
      * instrument configurations

---+++ Examples

---+++ Questions:
   * how to handle data for unknown instrument ?
   * how to store an instrument_mode (single string, fields concatenation...)
   * How to solve ambiguity for MIDI (and MATISSE) between HIGH_SENS and SCI_PHOT ?



---++ Group by nights
Function: split by observation nights %BR%
Inputs: OI_DATA tables :  (DATE-OBS + TIME ) or  (MJD), ARRNAME %BR%
        OI_ARRAY tables %BR%
Outputs: List of observation nights

---+++ Use cases
   * handle oifits without OI_ARRAY

---+++ Impact
   * jmal : date, coords
   * oitools : add derived column (NightID for each data line)
   * oiexplorer-core : computing NightID


---+++ Examples


---++ General
   * oiexplorer-core must provide for every table row : the targetId, nightId, targetUuid
   * do we have to refresh/compare data retrieved by simbad
This topic: Jmmc/Software > OiDbTechnicalSpecs
Topic revision: r4 - 2014-04-09 - PatrickBernaud