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Designations and quality control

The observations ingested into the archive undergo some tests to verify their quality. Most of the times the observations are archived, whatever their quality, and this procedure is intended to provide a meaningful description of the observation.
A major step in this process is to check if the target is properly identified. The main cases of mis-identifications occur because:

  • The name provided in the input catalogue is ambigous or unrecognizable
  • The telescope is pointed in a direction different than the catalogued one (detected as a discrepancy between the positions of the telescope and input catalogue)
  • The object was wrongly identified

Identification of the targets

The procedure proceeds through automatic attempts to recognize the target, and the failed cases are handled to the archive curators for a "manual" identification.

Recognition in our internal catalogue

The first step is to rewrite the name provided in the input catalogue in a canonical form following some rules: (i) For catalogues known to our algorithm, the name is reshaped to comply with a template, for example, HD 1 is rewritten to HD000001. (i) For other names, the names are converted to upper-cases, leading and trailing spaces are trimed and single spaces are replaced with a single '_' (underscore, IAU recommended equivalents for blanks in names). Since this algorithm is applied to any name passed to the system, this enables comparisons and searches.
The second steps consists in searching the canonical form in our internal database of astronomical names (inherited from the HyperLeda database), where the names from different catalogues are cross-identified. A successful match allows us to adopt a 'principal' designation of this object. This process makes possible to recognize 'aliases' of the same object belonging to different catalogues. The target names from important catalogues of stars, like HD, BD, HIP, TYC ... are usually well recognized.

A couple of particular common targets are recognized with a dedicated piece of code. These are namely SUN (when named as "soleil"), MOON (either named "moon" or "lune") and SKY (often named "ciel").

About 70% of the targets are properly recognized at this step.

Recognition in Simbad

The Simbad database, from the CDS in Strasbourg, provides a much larger set of names (in particular for the stars, since HyperLeda is primarily scoped for extragalactic objects). Therefore, the names that we did not recognize locally are sumbitted to Simbad and a set of names from the catalogues locally recognized are retrieved. The returned name are then submitted to our local resolver, as in the case above. About 5% of the targets are recognized by Simbad and half of them are then identified locally.

Manual identification

The remaining 25% of the targets are identified manually. Since the name provided in the input catalogue is not recognized neither locally or by Simbad, we do our best to understand what the target is, and assign a name that can be either recognized locally or by Simbad. A number of these objects are solar systems objects (planets and asteroids) which are not index in HyperLeda nor Simbad. Others are valid names which are mis-spelled or internal identification proper to a particular project.

This is an extremely time consuming task, and we are deeplly grateful to the observers who take care of providing easily recognizable names.

See the table of manually identified targets.

Unidentified objects

Some targets are not identified with celestial sources. A small fraction of them are from recent observations that we will shortly review, and most of the others are test observation of presumably little scientific value.

See the table of unidentified targets.

Consistency tests

Comparing the position of the target in the input catalogue with the position of the telescope can in principle be efficient to detect and correct mis-identifications. Unfortunately, at variance with the time when the Elodie spectrograph was in operation, the telescope control system (TCS) had several failures during the first years of operation of Sophie. This was due to ageing hardware and software that had to be replaced, and because of this, for some periods of time the telescope coordinates were not transmitted to the archive, or they were corrupted. We identified and flagged most of the affected data, and the consistency tests are carried-on with the remaining observations. Since 2010-05-01 the TCS is stable and the reported telescope position is reliable.
The table of observations with inconsistent target and telescope positions reports the cases that we did not yet solve. The list may contain some remaining cases of telescope dysfunctioning, some test/calibration observations and some mis-identifications. In any case we are working on clarifying those cases.

Last updated on : 15.04.2014