TheSkySearchers

I've noticed that in SkyTools there's a spiral galaxy with 2 NGC designations (or so it seems). It lists the object as "NGC 3373 (NGC3389)". I thought it was odd so did some searching for this and similar objects. This lead to more confusion as I came across galaxies with that same type of designation. For example, NGC 3384 is also known as NGC 3371.

Are some of those designations referring to 'galaxy clusters' or something since some of these seem to be in galaxy groups? My bit of searching has not helped my understanding (quite the opposite) so I figured I would ask here to see if anyone might be able to clarify.

Check out the notes: https://simbad.cds.unistra.fr/simbad/si ... =submit+id

Ha! Thanks for that. I guess it shouldn't seem strange that astronomers mess things up once in a while too.

[Edit] Also meant to add that while the detailed notes answered some questions it also added more.

That is fairly normal for astronomy in general
Glad it help at least a bit.

By the 1990s, it was obvious the NGC had a a ton of errors--nonexistent objects, duplicate sightings, position errors, etc.
An attempt was made to clean it up, but it still had around 700+ missing objects.
An organization known as the NGC/IC project got started, with people observing each one, pinning down the correct coordinates, and looking at original 18th and 19th century notes to identify errors.
The number of unidentifiable objects reduced significantly. A few errors were identified that were not corrected, like NGC90 and 91, which were reversed. Too many studies and pictures had taken place, so reversing the numbers would make a hundred years of study
become problematic.
You can find the latest corrections here:
http://www.klima-luft.de/steinicke/index_e.htm
The point is, the NGC catalog has a lot of errors in it that have not been cleaned up and probably will never be, due to the poor notes left by the discoverers.
Still, having a more corrected version is a good thing, even if some NGC objects will never be identified (if they were real).

It is common, especially on the nearer (larger angular size) galaxies to have NGC numbers for specific features within the galaxy, typically star-forming regions, as well as an overall designation for the galaxy itself.