Quality controls

We have performed data checks and quality controls on the data stored in the database, both on internal and external bases. Many inconsistencies were found. When an obvious solution could be found, corrections were applied to the stellar identifications or photometric data. If not, the number of measurements has been set to null (0), so that the suspect observations do not influence the computation of mean values, when relevant.

We have prepared lists of errors and problems found. They can be reached from the description of the characteristics of each photometric system.

Internal checks

Each time there is at least two independent sources of measurements for a star in a photometric system, we have compared them and looked for larger than normal differences.

When some were found, we have carefully checked the values entered in the computer or the published identifications. However, in many cases, it was not possible to find any reliable explanation for the discrepancies.

The problems may be due either to the observation of a wrong object or to some misprint.

External checks

We have also compared similar data from several photometric systems. For example, we have checked that the V magnitudes published for the same star in various systems are in good agreement. Again, any abnormal difference may reveal a problem on the measurements or the star identification.

We shall also work graphically. We plot diagrams with photometric indices of similar astrophysical content (for example B-V versus b-y) and examine the most deviant stars.

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Last update: 16 March 1996