<p>For Ephemeris Type, choose Observer Table. Under Table Settings, select:</p>
<blockquote>
<ol start="14">
<li>☑ Observer sub-lon &amp; sub-lat</li>
</ol>
</blockquote>
<p>They don't use the word &quot;libration&quot; because it also applies to other bodies e.g. Mars. Then the output has:</p>
<pre><code> 'ObsSub-LON ObsSub-LAT' =
   Apparent planetodetic longitude and latitude of the center of the target
disc seen by the OBSERVER at print-time. [...]
</code></pre>
<p>Note that at 1 lunar distance, the observer's geographic location can change the results by as much as 1° due to parallax.</p>

CC BY-SA 4.0
2023-10-06T16:36:17.650Z
2023-10-06T16:36:17.650Z
Mike G
<p>I've been searching Horizons settings to find lunar librations but can't find. How can I get the libration data?</p>
<p>So I have tested this <a href="https://ssd.jpl.nasa.gov/horizons/app.html#/" rel="nofollow noreferrer">Horizons Web Application</a> and selected Moon as the target. Whether I select Vector Table or Osculating Orbital elements or Observer Table as Ehpemeris Type there's no lunar libration column in the output data. I'm expecting two parameters like libration_lon, libration_lat or something. I've tested both ecliptic and equatorial reference planes (in Table Settings).<a href="https://i.sstatic.net/PMf5q.png" rel="nofollow noreferrer"><img src="https://i.sstatic.net/PMf5q.png" alt="Screenshot of Horizons Web Application" /></a></p>

CC BY-SA 4.0
2023-10-06T14:42:12.507Z
Where exactly did you look and what exactly did you search?
planetmaker
CC BY-SA 4.0
2023-10-06T15:11:58.720Z
@planetmaker I edited the question with some details.
user3202179
CC BY-SA 4.0
2023-10-06T16:05:22.317Z
Thanks. I also added the actual link to the web app.
planetmaker
<the-moon><lunar-libration>
Get Moon libration data from JPL Horizons
user3202179
# Get Moon libration data from JPL Horizons

(Asked by: username_0 on 2023-10-06)

I've been searching Horizons settings to find lunar librations but can't find. How can I get the libration data?

So I have tested this [Horizons Web Application](https://ssd.jpl.nasa.gov/horizons/app.html#/) and selected Moon as the target. Whether I select Vector Table or Osculating Orbital elements or Observer Table as Ehpemeris Type there's no lunar libration column in the output data. I'm expecting two parameters like libration\_lon, libration\_lat or something. I've tested both ecliptic and equatorial reference planes (in Table Settings).[![Screenshot of Horizons Web Application](https://i.sstatic.net/PMf5q.png)](https://i.sstatic.net/PMf5q.png)

**Tags:** the-moon, lunar-libration

> **Comments:**
> **username_1**: Where exactly did you look and what exactly did you search?  
> **username_0**: @username_1 I edited the question with some details.  
> **username_1**: Thanks. I also added the actual link to the web app.  

---

## 1 answers

### Answer by username_2 on 2023-10-06. Score: 5 | Accepted answer

For Ephemeris Type, choose Observer Table. Under Table Settings, select:


☑ Observer sub-lon & sub-lat


They don't use the word "libration" because it also applies to other bodies e.g. Mars. Then the output has:
 'ObsSub-LON ObsSub-LAT' =
   Apparent planetodetic longitude and latitude of the center of the target
disc seen by the OBSERVER at print-time. [...]

Note that at 1 lunar distance, the observer's geographic location can change the results by as much as 1° due to parallax.


---

