[vsnet-chat 4883] Re: new Tycho variables & HD 235749

[Brian Skiff <bas@lowell.edu>]

     Knowing a little bit about how te SIMBAD database has been built,
I can hazard a guess as to why the NSV is not fully entered into the system.
The guess is that the catalogue was not available in machine-readable form
until sometime in the past decade.  The VizieR ReadMe documentation suggests
it wasn't until Goddard put out the CD with "selected astronomical
catalogues" in 1992 that you could get the NSV in a workable form short of
keying it in oneself.  By that time the SIMBAD folks were swamped with
trying to keep up with the new stuff coming in (with insufficient people and
computing resources to do it quite right), so things such as the NSV were
left behind.  Thus the only NSV numbers present in SIMBAD are those that
have been mentioned in some more recent paper or catalogue.  To a great
extent, the long lists of coords and IDs that Timo Kinnunen and I published
last year in the IBVS (and which I plan to crank up on again soon) were
simply to force the issue of getting positions and IDs linked in SIMBAD
(they were only secondarily to aid the GCVS folks---although I hope they've
found them useful, too!).
     It would probably be possible to request that the CDS folks add the NSV
and NSVS to SIMBAD in full.  There might still be the problem of linking
the names with others (HD, BD, IRAS, etc.), which is the sort of work that
takes a lot of time, so it might not be straightforward for it to be done.
You would end up having to search SIMBAD by position---which is now by far
the preferred mode (name-only searches will too often miss un-linked 
entries).

\Brian

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