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Re: [vsnet-chat 6390] Re: [vsnet-id 795] AAVSO names in SIMBAD
> I recommended long ago that people *not* use USNO-A or
> UCAC zone/number names, just for the reason that they were likely to
> change with later releases. You have seen that with
> USNO-SA, USNO-A1.0, USNO-A2.0 and now USNO-B1.0, for example.
Every time Arne (or someone) comments on this, I need to make a comment ;-)
(This is probably a sort of FAQ which needs to be summarized in some place).
A few important things.
(1) USNO Ax.x zone-number (or Bx.x) is the only existing correct
_identifier_ for the USNO catalogs.
(2) An identifier should uniquely refer to an object in some catalog.
(3) An identifier should be uniquely determined at least within the
same catalog.
(2) and (3) are necessary basic properties of the nomenclature systems.
A system lacking either of them can easily become a fuzzy one, and
lose the merits of single-to-single association.
(4) Coordinate-based expressions for USNO catalogs do not satisfy (3),
and potentially not (2). There is no "fixed coordinate-based
nomenclature" in the USNO catalogs.
(5) Do not confuse identifiers with non-identifiers. "A star at xx:xx:xx
+xx:xx:xx in USNO Ax.x" is descriptive, but is not unique in expression.
Even "a star recorded at the xxxxxxxx bytes in USNO Ax.x file xxxx"
is equally descriptive.
(6) There have been too much misunderstanding between "proper identifiers"
and "possible descriptions" for specifying an entry in catalogs.
The latter should not supersede the former.
Conclusion: use zone + number expression for USNO identifiers.
Regards,
Taichi Kato
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