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

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
Inputs: OI_WAVELENGTH tables : INSNAME + EFF_WAVE_min/max + NB_EFF_WAVE + EFF_BAND
knowledge instrument_mode database
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
Inputs: OI_DATA tables : (DATE-OBS + TIME ) or (MJD), ARRNAME
OI_ARRAY tables
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