Expert: Tom Whiting - 11/3/2005

Question
I was recently suprised to find a number of 'single star' entries in the Revised NGC / IC catalogue, as I always believed that it contained only Nebula / Galaxy / Clusters etc.
My question is: Despite quite intensive Google'ing on the matter I cannot find any cross referencing between HD or HR star records and NGC / IC 'single star' objects. Do some 'single star' objects in the NGC / IC relate to HD or HR records (or any other star records)? Am I being ignorant on this matter? If not is it possible to cross reference these records?

Many Thanks,

Shortcake.  

Answer
Hi Shortcake,
It's my understanding that the project...re-visiting all NGC
and IC objects to eliminate errors, it not yet completed., See
http://www.ngcic.org/
and punch on "Project Mission".....

So it's quite possible that they just aren't finished with the new revised NGC/IC catalogue as yet.
(unless I am way behind in my information).

As far as single point objects, it's quite possible what you
might be seeing (or researching) are very, very small /distant planetary nebulae--which rightly have either an NGC or IC number....some  (actually, a lot of them out there) are only one or two arc-second diameters, or smaller, which would look virtually stellar in nature, in our small amateur telescopes.
(Even with the application of an O-III nebular filter).

As far as cross-referencing HD stars and other catalogues,
I know of no way of doing it because I am not a computer
expert, nor a faint "star" expert....I mainly specialize in deep sky objects which show a decent brightness (say brighter
than 14th magnitude) and a measureable, easily viewed  diameter;  so I even avoid those small, faint planetaries (like PK's) that are too difficult to resolve by 63 year old eyes.
Hope all this helps,  (but it's the best I can do for you, )
Clear Skies,
Tom Whiting
Erie, PA


FOLLOW UP
Oh, I just learned something....go to that site listed above,
and punch on Corrected NGC/IC objects, go to Harold
Corwin's data base, punch on NGC objects # 6000 to 6999;
go down to say, NGC 6910, and on that object, they actually
list the HD number of the star....so there is a database
that you might be able to use that perhaps cross-references
the HD star number involved.
Clear Skies,
Tom Whiting
Erie, PA