<p>There is doubtless a way to do it in AstroPy, but in case you’re interested, the Skyfield library both supports the operations of loading the Hipparcos catalog and computing apparent coordinates. Here is its overall guide to positions, with running examples in the text:</p>
<p><a href="https://rhodesmill.org/skyfield/stars.html" rel="nofollow noreferrer">https://rhodesmill.org/skyfield/stars.html</a></p>
<p>And here's a more elaborate and realistic example star plot, using the stereographic projection, which is my favorite when doing astronomical work:</p>
<p><a href="https://rhodesmill.org/skyfield/example-plots.html#drawing-a-finder-chart-for-comet-neowise" rel="nofollow noreferrer">https://rhodesmill.org/skyfield/example-plots.html#drawing-a-finder-chart-for-comet-neowise</a></p>
<p>In Skyfield you will account for location and time of year by using a specific time and location when generating your apparent positions, a maneuver that's included in this example:</p>
<p><a href="https://rhodesmill.org/skyfield/examples.html#at-what-angle-in-the-sky-is-the-crescent-moon" rel="nofollow noreferrer">https://rhodesmill.org/skyfield/examples.html#at-what-angle-in-the-sky-is-the-crescent-moon</a></p>

CC BY-SA 4.0
2020-09-12T04:48:25.253Z
I wanted to say that this is link-only but in this case I remember several posts from years ago where I posted code blocks in Python 2 for an early Skyfield and now none of that is even close to useful. So I think in this particular case this is a good way. :-)
uhoh
CC BY-SA 4.0
2020-09-14T23:32:14.187Z
Thank you, Skyfield has been very useful for this! I very much appreciate both the answer and the package.
Jacob
CC BY-SA 4.0
2020-09-11T18:58:30.943Z
2020-09-11T18:58:30.943Z
Brandon Rhodes
<p>I'd like to be able to generate star maps using Python, similar to what is done at <a href="http://www.fourmilab.ch/cgi-bin/Yoursky" rel="nofollow noreferrer">YourSky</a>. I believe this is possible with <a href="http://astropy.org" rel="nofollow noreferrer">Astropy</a> and the details provided in <a href="https://astronomy.stackexchange.com/questions/31987/calculating-the-range-of-visible-right-ascension-and-declination-from-specific-l">this question</a>. I can import stars from Hipparcos and use <a href="http://learn.astropy.org/rst-tutorials/plot-catalog.html?highlight=filtertutorials" rel="nofollow noreferrer">this tutorial</a> to map stars using a Mollweide projection.</p>
<p>What calculations are needed to adjust for location on earth and time of year? Is the Mollweide projection the appropriate projection to use, or would something else be better?</p>
<hr />
<p>Also related: <a href="https://astronomy.stackexchange.com/questions/36147/correct-units-to-use-while-plotting-mollweide-projection-of-sky-chart-with-ra-an">Correct units to use while plotting mollweide projection of sky chart with RA and Dec values, matplotlib</a></p>

CC BY-SA 4.0
2020-09-11T18:24:27.787Z
See also [How to make a star chart from entries in a Bright Star Catalogue?](/q/35864)
Mike G
<python><star-maps>
How can I calculate the apparent position of stars as seen from a location on Earth at a specific time?
Jacob
# How can I calculate the apparent position of stars as seen from a location on Earth at a specific time?

(Asked by: username_0 on 2020-09-11)

I'd like to be able to generate star maps using Python, similar to what is done at [YourSky](http://www.fourmilab.ch/cgi-bin/Yoursky). I believe this is possible with [Astropy](http://astropy.org) and the details provided in [this question](https://astronomy.stackexchange.com/questions/31987/calculating-the-range-of-visible-right-ascension-and-declination-from-specific-l). I can import stars from Hipparcos and use [this tutorial](http://learn.astropy.org/rst-tutorials/plot-catalog.html?highlight=filtertutorials) to map stars using a Mollweide projection.

What calculations are needed to adjust for location on earth and time of year? Is the Mollweide projection the appropriate projection to use, or would something else be better?

---

Also related: [Correct units to use while plotting mollweide projection of sky chart with RA and Dec values, matplotlib](https://astronomy.stackexchange.com/questions/36147/correct-units-to-use-while-plotting-mollweide-projection-of-sky-chart-with-ra-an)

**Tags:** python, star-maps
> **Comments:**
> **username_1**: See also [How to make a star chart from entries in a Bright Star Catalogue?](/q/35864)  

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## 1 answers

### Answer by username_2 on 2020-09-11. Score: 3 | Accepted answer

There is doubtless a way to do it in AstroPy, but in case you’re interested, the Skyfield library both supports the operations of loading the Hipparcos catalog and computing apparent coordinates. Here is its overall guide to positions, with running examples in the text:

<https://rhodesmill.org/skyfield/stars.html>

And here's a more elaborate and realistic example star plot, using the stereographic projection, which is my favorite when doing astronomical work:

<https://rhodesmill.org/skyfield/example-plots.html#drawing-a-finder-chart-for-comet-neowise>

In Skyfield you will account for location and time of year by using a specific time and location when generating your apparent positions, a maneuver that's included in this example:

<https://rhodesmill.org/skyfield/examples.html#at-what-angle-in-the-sky-is-the-crescent-moon>

> **Comments:**
> **username_3**: I wanted to say that this is link-only but in this case I remember several posts from years ago where I posted code blocks in Python 2 for an early Skyfield and now none of that is even close to useful. So I think in this particular case this is a good way. :-)  
> **username_0**: Thank you, Skyfield has been very useful for this! I very much appreciate both the answer and the package.  

---

