<p>Those vendors don't need an API, and neither do you.
What their "how it works" pages do talk about are star catalogs and map projections.</p>

<p>The <a href="http://cdsarc.u-strasbg.fr/viz-bin/cat/V/50" rel="noreferrer">Bright Star Catalog</a> has about 9000 stars down to magnitude 6, as faint as most people can see in a dark sky without optical aid.
The <a href="http://cdsarc.u-strasbg.fr/viz-bin/cat/I/311" rel="noreferrer">Hipparcos catalog</a> has about 100k stars down to magnitude 9 or 10.
The key data for a star map are <a href="https://en.wikipedia.org/wiki/Celestial_coordinate_system" rel="noreferrer">equatorial coordinates</a> (right ascension, declination) and V-band <a href="https://en.wikipedia.org/wiki/Apparent_magnitude" rel="noreferrer">apparent magnitude</a>.
For an all-sky map, which typically uses a <a href="https://en.wikipedia.org/wiki/Stereographic_projection" rel="noreferrer">stereographic projection</a> to plot everything within 90&deg; of the zenith (RA = <a href="https://aa.usno.navy.mil/data/docs/siderealtime.php" rel="noreferrer">sidereal time</a>, Dec = geographic latitude), transformation to horizontal coordinates may be a useful intermediate step.</p>

<p>If you like working in Python, either <a href="https://rhodesmill.org/skyfield/" rel="noreferrer">Skyfield</a> or <a href="https://www.astropy.org/" rel="noreferrer">Astropy</a>/<a href="https://astroquery.readthedocs.io/en/latest/" rel="noreferrer">Astroquery</a> can help you retrieve and process the data but will not plot the map.</p>

CC BY-SA 4.0
2019-08-02T16:38:26.217Z
Thank you very much Mike, really appreciate the help!
Akalife
CC BY-SA 4.0
2020-05-19T17:53:45.167Z
I am also looking for this info. The abive answer sounds really smart bust does not offer and answer. It simply tells the person to learn PYTHON. Which is not how these are done. They are tied to an API. We are both wondering WHICH API and the links to them.
Old F'n School
CC BY-SA 4.0
2020-05-19T21:31:41.537Z
@OldF'nSchool I looked for a web API but didn't find one. Any programming language will do.
Mike G
CC BY-SA 4.0
2020-10-02T01:07:22.643Z
@OldF'nSchool at some point a question ceases to be about Astronomy at which point it no longer belongs on this site. For example [How (the heck) does Astrometry.net work?](https://astronomy.stackexchange.com/q/33575/7982) was on topic because it asks about the underlying astronomical image processing algorithm rather than the API. If the question is about web apps then *rather than complaining here*, perhaps a similar but non-identical question can be posted in [Web Applications SE](https://webapps.stackexchange.com/) focusing on how those applications work.
uhoh
CC BY-SA 4.0
2019-08-01T19:45:15.747Z
2019-08-01T19:45:15.747Z
Mike G
<p>The ones used by underluckystars.com and thenightsky.com</p>

<p>I have found several but I am having difficulty finding a working updated version, has anyone come across this API, or know where I can find it?</p>

CC BY-SA 4.0
2019-08-01T10:03:30.660Z
What do you exactly want: to find a beautiful star map or an accurate star map?
User123
CC BY-SA 4.0
2019-08-02T16:22:41.593Z
I want a webapp that creates accurate starmaps like those sites
Akalife
CC BY-SA 4.0
2020-11-20T06:20:38.123Z
you can now use astronomyapi.com api to do this. it's free
astroanu
<star-maps>
I am looking for the SKYMAP Api (To create nightsky/star maps)
Akalife
# I am looking for the SKYMAP Api (To create nightsky/star maps)

(Asked by: username_0 on 2019-07-31)

The ones used by underluckystars.com and thenightsky.com

I have found several but I am having difficulty finding a working updated version, has anyone come across this API, or know where I can find it?

**Tags:** star-maps

> **Comments:**
> **username_1**: What do you exactly want: to find a beautiful star map or an accurate star map?  
> **username_0**: I want a webapp that creates accurate starmaps like those sites  
> **username_2**: you can now use astronomyapi.com api to do this. it's free  

---

## 1 answers

### Answer by username_3 on 2019-08-01. Score: 7 | Accepted answer

Those vendors don't need an API, and neither do you.
What their "how it works" pages do talk about are star catalogs and map projections.

The [Bright Star Catalog](http://cdsarc.u-strasbg.fr/viz-bin/cat/V/50) has about 9000 stars down to magnitude 6, as faint as most people can see in a dark sky without optical aid.
The [Hipparcos catalog](http://cdsarc.u-strasbg.fr/viz-bin/cat/I/311) has about 100k stars down to magnitude 9 or 10.
The key data for a star map are [equatorial coordinates](https://en.wikipedia.org/wiki/Celestial_coordinate_system) (right ascension, declination) and V-band [apparent magnitude](https://en.wikipedia.org/wiki/Apparent_magnitude).
For an all-sky map, which typically uses a [stereographic projection](https://en.wikipedia.org/wiki/Stereographic_projection) to plot everything within 90° of the zenith (RA = [sidereal time](https://aa.usno.navy.mil/data/docs/siderealtime.php), Dec = geographic latitude), transformation to horizontal coordinates may be a useful intermediate step.

If you like working in Python, either [Skyfield](https://rhodesmill.org/skyfield/) or [Astropy](https://www.astropy.org/)/[Astroquery](https://astroquery.readthedocs.io/en/latest/) can help you retrieve and process the data but will not plot the map.

> **Comments:**
> **username_0**: Thank you very much username_3, really appreciate the help!  
> **username_4**: I am also looking for this info. The abive answer sounds really smart bust does not offer and answer. It simply tells the person to learn PYTHON. Which is not how these are done. They are tied to an API. We are both wondering WHICH API and the links to them.  
> **username_3**: @username_4 I looked for a web API but didn't find one. Any programming language will do.  
> **username_5**: @username_4 at some point a question ceases to be about Astronomy at which point it no longer belongs on this site. For example [How (the heck) does Astrometry.net work?](https://astronomy.stackexchange.com/q/33575/7982) was on topic because it asks about the underlying astronomical image processing algorithm rather than the API. If the question is about web apps then *rather than complaining here*, perhaps a similar but non-identical question can be posted in [Web Applications SE](https://webapps.stackexchange.com/) focusing on how those applications work.  

---

