Code names for astronomical objects

[Andrewmelon]

What does the messier symbol mean and what is it used for? Also, ngc, what does that mean? Can someone please explain a lot of the symbols and codes of these astronomical objects?

[Ruud]

Hi Andrew,

Messier identified objects that look like comets, but are not. He was a comet hunter and used his list to avoid mistakes. I suppose he numbered the objects in the order which he found them. Messier lived in the 18th century. His objects are ideal for amateur astronomers. They are mostly nebulae, galaxies, open clusters and globular clusters.

Patrick Moore later expanded Messier's list with the Caldwell catalogue: more nice objects for amateurs. Moore published his list in the 20th century.

NGC is the New General Catalogue. A longer list of objects that was compiled in the 18th century. There are many more catalogues of astronomical objects, like the Index Catalogue (IC). Many objects appear in more than one catalogue.

The Hipparcos catalogue is a list of some hundred thousand stars whose positions and properties were measured by the European Hipparcos satellite. There's a new European satellite, Gaia, which is currently measuring positions  and properties of a thousand million stars.

All these catalogues (there are more) were and are used to refer to objects in space, to make sure that people can communicate and compare their observations.

[ronin]

Messiers are as said objects that were in effect "not comets", I gather that the original list was only about 45. After he died the list was expanded to include ones that he referred to but did not get round to incorporating - for whatever reason. M101 is still open to debate. Oddly I think you will find that his assistants name Pierre Mechain is against a lot of them.

This makes interesting reading, CM's original and you can read how/why M1 is first, he was comet observing and what is now M1 happened top be close.

Messier-1771

Messier is often referred tp as a catalogue of things not to bother about, Messier was simply not interested in them. Patrick Moore made the Caldwell Catalogue of the same number of objects as Messier that were "interesting" objects, C14 being the obvious/easy.

The remainder are to an extent surveys. NGC is a fair size, SAO and HIP are I think just stars but most stars we can see will have a reference in one or both - look up Betelgeuse in Wiki to find out how many catalogue names it has.

I suppose one day there will be a Gaia catalogue of stars, so clean out your hard drive if you want that one.

[Vox45]

I explained to my daughter how to find objects in Stellarium using Messier's list

As she was 4 or 5 at the time I made it really easy for her ... press F3 then press M and then a number using only 2 digits (at first she would enter M844357897594.. I came up with this rule to avoid this)

One day she called me after 'discovering' M51 and as she was drawing it in her little sketchbook I asked her what were the white specks she drew all over.

Her answer: "that is the light from the flash when Mr. Messier took the picture"

kids

[Andrewmelon]

Thanks everyone!!