<p>There exist many <a href="http://en.wikipedia.org/wiki/List_of_astronomical_catalogues" rel="nofollow">astronomical catalogs</a>, reaching from rather simple catalogs like the <a href="http://en.wikipedia.org/wiki/Bayer_designation" rel="nofollow">Bayer catalog</a> for stars, or the <a href="http://en.wikipedia.org/wiki/List_of_Messier_objects" rel="nofollow">Messier catalog</a> for galaxies, nebulae, etc., to huge catalogs with millions of entries. <a href="http://en.wikipedia.org/wiki/Gaia_%28spacecraft%29" rel="nofollow">A catalog with about a billion objects</a> is scheduled for 2022.</p>

<p>There exist also <a href="http://www.deepskywatch.com/Deep-Sky-atlas/comparison.html" rel="nofollow">printed editions</a> of some catalogs.</p>

<p>Objects in the sky have several properties, by which they can be described and mostly identified.</p>

<p>One of the most frequently used properties is the position in the sky. From the local geographic position and the time, the observed position of the object can be translated into a celestial coordinate system, e.g. the <a href="http://en.wikipedia.org/wiki/Equatorial_coordinate_system" rel="nofollow">equatorial coordinate system</a>. The position of an object is described in this system by <a href="http://en.wikipedia.org/wiki/Declination" rel="nofollow">declination</a> and <a href="http://en.wikipedia.org/wiki/Right_ascension" rel="nofollow">right ascension</a>.</p>

<p>Two other frequently used properties are <a href="http://en.wikipedia.org/wiki/Apparent_magnitude" rel="nofollow">magnitude</a> and <a href="http://www.physics.uc.edu/~hanson/ASTRO/LECTURENOTES/W07/Stars/Page3.html" rel="nofollow">color</a>.</p>

<p>Also frequently used are patterns of stars, meaning their relative position to each other, beginning with <a href="http://en.wikipedia.org/wiki/Lists_of_stars_by_constellation" rel="nofollow">star constellations</a>.</p>

<p>The analysis of <a href="http://www.physics.sjsu.edu/tomley/ObjectSpectra/Rigel.html" rel="nofollow">steller spectra</a> allows a more detailed identification.</p>

<p>Longer term observations may uncover <a href="http://en.wikipedia.org/wiki/Variable_star" rel="nofollow">variability</a> and <a href="http://en.wikipedia.org/wiki/Proper_motion" rel="nofollow">proper motion</a> as additional properties.</p>

<p><a href="http://heasarc.gsfc.nasa.gov/W3Browse/star-catalog/bsc5p.html" rel="nofollow">Here</a> is a description of parameters (including properties) provided by the BSC5p catalog.</p>

CC BY-SA 3.0
2014-02-08T18:44:21.610Z
What all details will this catalog contain? Can you give a little more details about the procedure one may go through to locate and identify an object he just saw in the sky in this catalog? I can assume it might require some skill and knowledge about this but could you give a general idea?
Mat J
CC BY-SA 3.0
2014-02-09T23:37:13.977Z
To use a simple example - one could go out at this time of year and (in the Northern Hemisphere) see Sirius, which is the brightest star in the sky, or Polaris, which is essentially due North and unmoving as a result. From that beginning we can look at the pattern in the atlas/catalogue and recognise the patterns from there.
adrianmcmenamin
CC BY-SA 3.0
2014-02-10T11:46:32.220Z
Yes, that's one of the usual ways to it. First look at the patterns of brighter stars for an overview, then go down into detail for fainter stars. Not far from Sirius you'll see e.g. Jupiter (moves over time), the brightest most object (besides Sun and Moon) at the moment. You'll also find the constellation Orion not far away from Sirius. At Orion you may e.g. go down into detail.
Gerald
CC BY-SA 3.0
2014-02-10T12:10:12.920Z
Here a nice introduction to february night sky, northern hemisphere: http://www.youtube.com/watch?v=AvCK4dJQrSw
Gerald
CC BY-SA 3.0
2014-02-08T17:55:09.320Z
2014-02-08T20:22:49.673Z
2014-02-08T20:22:49.673Z
Gerald
<p>I've always wondered how someone looking at the sky into the enormous amount of stars and other things out there figures out that whether it is an already identified object or is he looking at something new? Is there some sort of tools like latitude and longitude to pin point something in the sky or some catalog where you can see if this is an identified object and what it is called, how it looks like and where it is located and all? </p>

<p>As you might have guessed, I don't have any science background, just asking out of a common man's curiosity, so please be gentle with the jargon you use.  </p>

CC BY-SA 4.0
2020-02-23T00:55:58.653Z
Just to note, for a long time you *didn't*.  For instance, Messier published his catalog not intending to document galaxies, nebulas and such, but to help identify things which *weren't* comets.  And dying stars were mistakenly identified as being "new".
Michael
<observational-astronomy>
How do one identify something they see in the sky?
Mat J
# How do one identify something they see in the sky?

(Asked by: username_0 on 2014-02-08)

I've always wondered how someone looking at the sky into the enormous amount of stars and other things out there figures out that whether it is an already identified object or is he looking at something new? Is there some sort of tools like latitude and longitude to pin point something in the sky or some catalog where you can see if this is an identified object and what it is called, how it looks like and where it is located and all?

As you might have guessed, I don't have any science background, just asking out of a common man's curiosity, so please be gentle with the jargon you use.

**Tags:** observational-astronomy

> **Comments:**
> **username_1**: Just to note, for a long time you *didn't*.  For instance, Messier published his catalog not intending to document galaxies, nebulas and such, but to help identify things which *weren't* comets.  And dying stars were mistakenly identified as being "new".  

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## 1 answers

### Answer by username_2 on 2014-02-08. Score: 5 | Accepted answer

There exist many [astronomical catalogs](http://en.wikipedia.org/wiki/List_of_astronomical_catalogues), reaching from rather simple catalogs like the [Bayer catalog](http://en.wikipedia.org/wiki/Bayer_designation) for stars, or the [Messier catalog](http://en.wikipedia.org/wiki/List_of_Messier_objects) for galaxies, nebulae, etc., to huge catalogs with millions of entries. [A catalog with about a billion objects](http://en.wikipedia.org/wiki/Gaia_%28spacecraft%29) is scheduled for 2022.

There exist also [printed editions](http://www.deepskywatch.com/Deep-Sky-atlas/comparison.html) of some catalogs.

Objects in the sky have several properties, by which they can be described and mostly identified.

One of the most frequently used properties is the position in the sky. From the local geographic position and the time, the observed position of the object can be translated into a celestial coordinate system, e.g. the [equatorial coordinate system](http://en.wikipedia.org/wiki/Equatorial_coordinate_system). The position of an object is described in this system by [declination](http://en.wikipedia.org/wiki/Declination) and [right ascension](http://en.wikipedia.org/wiki/Right_ascension).

Two other frequently used properties are [magnitude](http://en.wikipedia.org/wiki/Apparent_magnitude) and [color](http://www.physics.uc.edu/~hanson/ASTRO/LECTURENOTES/W07/Stars/Page3.html).

Also frequently used are patterns of stars, meaning their relative position to each other, beginning with [star constellations](http://en.wikipedia.org/wiki/Lists_of_stars_by_constellation).

The analysis of [steller spectra](http://www.physics.sjsu.edu/tomley/ObjectSpectra/Rigel.html) allows a more detailed identification.

Longer term observations may uncover [variability](http://en.wikipedia.org/wiki/Variable_star) and [proper motion](http://en.wikipedia.org/wiki/Proper_motion) as additional properties.

[Here](http://heasarc.gsfc.nasa.gov/W3Browse/star-catalog/bsc5p.html) is a description of parameters (including properties) provided by the BSC5p catalog.

> **Comments:**
> **username_0**: What all details will this catalog contain? Can you give a little more details about the procedure one may go through to locate and identify an object he just saw in the sky in this catalog? I can assume it might require some skill and knowledge about this but could you give a general idea?  
> **username_3**: To use a simple example - one could go out at this time of year and (in the Northern Hemisphere) see Sirius, which is the brightest star in the sky, or Polaris, which is essentially due North and unmoving as a result. From that beginning we can look at the pattern in the atlas/catalogue and recognise the patterns from there.  
> **username_2**: Yes, that's one of the usual ways to it. First look at the patterns of brighter stars for an overview, then go down into detail for fainter stars. Not far from Sirius you'll see e.g. Jupiter (moves over time), the brightest most object (besides Sun and Moon) at the moment. You'll also find the constellation Orion not far away from Sirius. At Orion you may e.g. go down into detail.  
> **username_2**: Here a nice introduction to february night sky, northern hemisphere: http://www.youtube.com/watch?v=AvCK4dJQrSw  

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