<p>That is part of this document: <a href="ftp://ssd.jpl.nasa.gov/pub/eph/planets/ioms/ExplSupplChap8.pdf" rel="nofollow noreferrer">The Whole Chapter 8</a></p>

CC BY-SA 4.0
2020-06-12T22:21:36.797Z
2020-06-12T22:21:36.797Z
Huy Pham
<p>I believe you are right, this is extracted from the &quot;Explantory supplement to the Astronomical Almanac (2006?)&quot;  (although it might date back to the 1960s...)</p>
<p>For example a similar <a href="ftp://ftp.lowell.edu/www_users/gerard/q_refs/keplerian%20elements%20for%20approx%20positions%20of%20major%20planets.pd" rel="nofollow noreferrer">PDF document</a> gives that citation.</p>
<p>The supplement is published in a separate binding from the main astronomical almanc and a new version is published each year.  Finding a copy may be challenging (its not going to be on the shelves of your local Waterstones).</p>

CC BY-SA 4.0
2020-06-07T21:50:08.667Z
2020-06-22T06:09:29.533Z
2020-06-22T06:09:29.533Z
James K
<p>Simple question here. I am working on something that needs to compute an orbital path using Keplerian Elements. When doing some research I came across this JPL page: <a href="https://ssd.jpl.nasa.gov/?planet_pos" rel="nofollow noreferrer">Click Here</a>. Within that link is a PDF titled <a href="https://ssd.jpl.nasa.gov/txt/aprx_pos_planets.pdf" rel="nofollow noreferrer">'Keplerian Elements for Approximate Positions of the Major Planets'</a>.</p>
<p>From what I can tell, it looks as though this PDF is an excerpt from a larger document. I'm making this assumption based off of the equation numbering. They start at 8-30. From my experience, this is usually due to the fact that there were more equations/sections preceding these equations in the overall doc.</p>
<p>I would love to explore this larger document in order to learn more and find some answers to questions that have developed after reading through the doc. Does anyone know what this document is taken from?</p>
<p>Thanks!</p>
<p><strong>Full Answer</strong></p>
<p>Just for those who are looking for a complete answer to this question, I wanted to combine the two answers below into one complete answer (without taking credit and making my own answer).</p>
<p>As JamesK mentions, this excerpt is actually pulled from the book, <em><a href="https://rads.stackoverflow.com/amzn/click/com/1891389858" rel="nofollow noreferrer" rel="nofollow noreferrer">Explanatory Supplement to the Astronomical Almanac</a></em>. I now own this book and it is chock full of useful information, including the excerpt I was looking for. It also dives into a deeper explanation of everything in the excerpt I posted. If you don't want to buy the book, Huy Pham provided a <a href="ftp://ssd.jpl.nasa.gov/pub/eph/planets/ioms/ExplSupplChap8.pdf" rel="nofollow noreferrer">link</a> to the full chapter that includes the excerpt I linked.</p>

CC BY-SA 4.0
2020-06-07T21:16:03.957Z
I don't see why you assume it is from a larger document.  It seems self contained.  I'd assume that is the complete document.
James K
CC BY-SA 4.0
2020-06-07T21:19:53.777Z
@JamesK It's the equations that make me think it's coming from somewhere else. Why would the equations be numbered the way the are? i.e. starting with 8-# for each equation. From my experience, that's only done when there are more sections and equations preceding them. Right? I'll update the question to reflect this.
Jee
CC BY-SA 4.0
2020-06-07T21:35:49.690Z
Good point.  will investigate further..
James K
<orbit><planet><orbital-mechanics><orbital-elements><kepler>
Keplerian Elements for Approximate Positions of the Major Planets
Jee
# Keplerian Elements for Approximate Positions of the Major Planets

(Asked by: username_0 on 2020-06-07)

Simple question here. I am working on something that needs to compute an orbital path using Keplerian Elements. When doing some research I came across this JPL page: [Click Here](https://ssd.jpl.nasa.gov/?planet_pos). Within that link is a PDF titled ['Keplerian Elements for Approximate Positions of the Major Planets'](https://ssd.jpl.nasa.gov/txt/aprx_pos_planets.pdf).

From what I can tell, it looks as though this PDF is an excerpt from a larger document. I'm making this assumption based off of the equation numbering. They start at 8-30. From my experience, this is usually due to the fact that there were more equations/sections preceding these equations in the overall doc.

I would love to explore this larger document in order to learn more and find some answers to questions that have developed after reading through the doc. Does anyone know what this document is taken from?

Thanks!

**Full Answer**

Just for those who are looking for a complete answer to this question, I wanted to combine the two answers below into one complete answer (without taking credit and making my own answer).

As JamesK mentions, this excerpt is actually pulled from the book, *[Explanatory Supplement to the Astronomical Almanac](https://rads.stackoverflow.com/amzn/click/com/1891389858)*. I now own this book and it is chock full of useful information, including the excerpt I was looking for. It also dives into a deeper explanation of everything in the excerpt I posted. If you don't want to buy the book, username_2 provided a [link](ftp://ssd.jpl.nasa.gov/pub/eph/planets/ioms/ExplSupplChap8.pdf) to the full chapter that includes the excerpt I linked.

**Tags:** orbit, planet, orbital-mechanics, orbital-elements, kepler

> **Comments:**
> **username_1**: I don't see why you assume it is from a larger document.  It seems self contained.  I'd assume that is the complete document.  
> **username_0**: @JamesK It's the equations that make me think it's coming from somewhere else. Why would the equations be numbered the way the are? i.e. starting with 8-# for each equation. From my experience, that's only done when there are more sections and equations preceding them. Right? I'll update the question to reflect this.  
> **username_1**: Good point.  will investigate further..  

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## 2 answers

### Answer by username_1 on 2020-06-07. Score: 5 | Accepted answer

I believe you are right, this is extracted from the "Explantory supplement to the Astronomical Almanac (2006?)" (although it might date back to the 1960s...)

For example a similar [PDF document](ftp://ftp.lowell.edu/www_users/gerard/q_refs/keplerian%20elements%20for%20approx%20positions%20of%20major%20planets.pd) gives that citation.

The supplement is published in a separate binding from the main astronomical almanc and a new version is published each year. Finding a copy may be challenging (its not going to be on the shelves of your local Waterstones).


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### Answer by username_2 on 2020-06-12. Score: 2

That is part of this document: [The Whole Chapter 8](ftp://ssd.jpl.nasa.gov/pub/eph/planets/ioms/ExplSupplChap8.pdf)


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