Resources \ Introduction to Calculating Charts by Hand
This is lesson 3 of the course
Introduction
To calculate charts by hand, there are resources that contain the data we need to be able to do so. I talk about and list those below. In the next article, I will provide an overview of the chart calculation process and then take you through the first steps. I thought I would be doing that in this article, with a brief section at the end for resources, but the resources section ended up being long, warranting its own post.
At the end of this article, I also list the two resources I used to learn how to calculate charts. If you'd like to learn how to do it without waiting for me to post each week, I can recommend the resources I list, which are free.
The Data We Need to Calculate Charts
General Information
To calculate charts, in addition to the event date, time and location that we are given, we need resources that provide the following data:
Latitude & Longitude
Sidereal time
Time zone
Planet Positions
House Cusp tables
Below, I explain why we need this information. Tried and true resources that can be used to gather this information include:
An ephemeris (plural: ephemerides)
A latitude, longitude, and time zone atlas
A table of houses
Ephemerides
An ephemeris lists planet positions for every day over the time period covered by the book. Some cover a year, some a decade, and some a century. They also include the sidereal time needed to make time adjustment calculations. To calculate a chart, we need a list of planet positions with which we can work.
Latitude, Longitude, and Time Zone Atlas
We need latitude, longitude, and time zone information to make various house cusp, time and planet position adjustments from the initial event data we are given. A latitude, longitude, and time zone atlas contains lists and tables with this information.
A Table of Houses
The houses are the twelve slices you see on an astrology wheel. Each house represents an area of life. The spokes of the wheel that create the twelve slices, or houses, are called house cusps. Although a complex topic, for our purposes we can say that, to individualize a chart, we need to determine the sign and degree of each house cusp. To do that, we use the latitude of the event location and the time of the event. For the time, we use sidereal time, which is different than the given event time.
Tables of houses list the degree and signs for the spokes, or house cusps, in both time and latitude increments. From this information, we can calculate the more precise cusps for a given chart.
If you haven’t had a chance to listen to the video in the previous lesson, I explain what sidereal time is and why we need to use it there. Here’s the link:
Resources
Below are the resources I know about and/or have used. I cover the book options first, then online resources. After that, I provide a compact list of all of them. Finally, I share the two free online resources I used to learn how to calculate charts.
Book Options
Although I would recommend holding off on buying books until you determine if it will be worth your while to invest in them, below are some that have all the information needed.
The American Ephemeris
by Neil F. Michelsen
There are many editions of this ephemeris covering different periods. For each period covered, the planet positions and sidereal time are listed for every day within the covered period. Each edition also contains additional information like moon phases, planet transits, and more. The ones that cover fewer years have more information, but the ones that cover a century have what we need to calculate charts.
The American Atlas and The International Atlas
by Thomas G. Shanks
The American Atlas covers the towns and cities in the United States. The International Atlas covers the rest of the world. (The US is not included in the international version.) For each location, the latitude and longitude are listed with a reference to a time zone table elsewhere in the book that has the time zone information.
The Michelsen Book of Tables
by Neil F. Michelsen
Houses are a complex topic. Suffice it to say that there are many different systems, each using different reference points to calculate the house cusps. Thus, no one list of houses works for all house systems.1
Looking for house tables in book form, I was only able to find ones for the Placidus and Koch systems. Michelsen's, The Michelsen Book of Tables, has both, so I list that.
To learn how to calculate charts, it does not matter which house system you use, but it is probably best to stick with one until you get the hang of it.
Parker's Astrology
by Derek Parker and Julia Parker
Some books cover all the basics of astrology, including how to calculate charts. They also provide you with the information you need to calculate the chart. I haven’t used Parker’s but it seems to fit the bill and seems to have a good reputation and is on my radar, so I’m listing that as an example. There are others out there. If the book covers chart calculation, it probably has the resources you need to do it. But be sure to check the table of contents to know for sure.
Update (7/30/2023): I took out the previous update saying Parker’s doesn’t go over how to calculate charts. It does! It’s just buried in the book and hard to find.
Online Options
Most of the information needed to calculate charts is available online for free. Astro.com, in particular, provides everything but the raw time zone data. The only thing to be aware of is that most sites provide this data for personal use only, including astro.com. That should be fine for learning how to calculate charts, so it makes sense to make use of them. I always like to find alternatives, so I also list the ones I’ve used where relevant. Be sure to look at the terms to know what’s allowable.
Latitude and Longitude
Find Latitude and Longitude
The website Find Latitude and Longitude is a US Naval Academy resource. When you enter a location or zip code, it pulls up the latitude and longitude. It's a little slow, and can be a little picky about what it accepts in terms of how you type in a location, but it works well enough and I'm willing to trust that the information is accurate given the source because of their need for accurate data to navigate.
Note that different sources give different latitudes and longitudes for the same places. That makes sense because each location covers a large area. Be aware, though, that if the latitude and longitude data you use for a given chart calculation is different from the data used by the source against which you check your work, your results may be further off than they otherwise might be. With this in mind, one of the things you can do when checking your work is compare your latitudes and longitudes with your source's.
Astro.com Atlas
The second resource is astro.com. Astro.com has all the resources needed for calculating charts except for raw time zone information. Although the name is confusing, you can use their Time-zone Atlas to find the latitude and longitude of a location.
Sidereal Time
Sidereal Time
Sidereal Time is a website of the Astronomical Applications Department of the US Government. It provides a handy sidereal time calculator. We'll go over how to use it when we get to that part. Just know that it's out there.
Astro.com Sidereal Time
Astro.com has ephemerides for 9,000 years. Like other ephemerides, these include the sidereal time needed to calculate charts.
Ephemerides
Astro.com Ephemerides
Astro.com is the best resource for online ephemerides. Their ephemerides cover 9,000 years and are considered the gold standard by many.
Table of Houses
Astro.com Table of Houses
Once again, Astro.com is the best resource. At this time, it’s the only online source I know about, but there may be others. They have tables of houses for every house system, detailed and compact versions, and versions for northern and southern latitudes. The compact versions list cusps in 4 minute time increments. The detailed versions list them in 1 minute increments. All of this will make sense when we get there. We’ll be using 4 minute increments for learning.
Time Zones
The challenge with time zones is finding information for event dates prior to the last few decades. In fact, while there are plenty of online resources that cover the current year, finding sources that go back beyond that is challenging. For this reason, we'll be using a date from this year to learn how to calculate charts.
Time.is
For current time zone data, I use Time.is.
Time and Date
Time and Date is a handy resource. You can use their time zone converter to find the time zone for a given location, date, and time. It has information for dates going back a few decades, but not beyond that.
All Resources \ Compact Lists
Books
The American Ephemeris (Neil F. Michelsen)
The American Atlas (Thomas G. Shanks)
The International Atlas (Thomas G. Shanks)
The Michelsen Book of Tables (Neil F. Michelsen)
Parker's Astrology (Derek Parker and Julia Parker)
Online
Latitude and longitude finder: Find Latitude and Longitude.com
Latitude and longitude finder: Astro.com Time-zone Atlas
Sidereal time calculator: Sidereal Time
Sidereal time (as part of their ephemeride): Astro.com Ephemerides
Current time zone information: Time.is
Time zone converter: Time and Date
Planet positions: Astro.com Ephemeris
Table of houses: Astro.com Tables of Houses
Resources for Learning How to Calculate Charts
I used two resources to learn how to calculate charts. The first was a Youtube video series put out by Dave Campbell (AFA). The second was a series of online articles published by Ken Ward on his trans4mind.com site. I provide links below. There are also plenty of books out there that take you through the process. I haven’t used them so can’t offer any advice about which one or ones to choose, though I’m interested in the Parker’s Astrology book I listed above.
With regard to the resources I used, I recommend starting with Dave Campbell's series, then moving on to Ken Ward's tutorial. Campbell's videos teach you the basic steps. Ward's articles, while a little harder to understand (at least they were for me), provide explanations for why the calculations are made. Thus, they complement each other well.
Be aware that Ward uses a slightly different approach than Campbell. It is for this reason that I recommend working through Campbell's videos first before moving on to Ward's article tutorials, i.e., get clear on one before moving on to the other. Ultimately, I found that Ward's articles helped fill in some of the gaps that were missing for me from Campbell’s videos but that Campbell’s videos were initially more accessible to me in terms of being able to follow the calculation steps.
The Resources I Used to Learn How to Calculate Charts
Dave Campbell's Chart Calculation Video Series on Youtube
How to calculate your birth chart by Dave Campbell AFA part 1 of 5
AFA Math How to calculate your birth chart, part 2 of 5 The American Federation of Astrologers
How to calculate birth chart part 3 of 5. The American Federation of Astrologers
How to Calculate birth chart part 4 of 5 , Natal Calculation, American Federation of Astrologers
How to calculate the birth chart part 5 of 5 The American Federation of Astrologers
Ken Ward's Chart Calculation Articles
For the online article tutorials published by Ken Ward, go to the Table of Contents for astrology on his trans4mind.com site. You will find links to all of the articles on chart calculation under the chart calculation section.
More Below
See below for links to the first two articles in the series and an announcement.
First Two Articles in the Series
First Article
Course Introduction: Astrology Chart Calculation
Watch now (4 min) | Note: If you prefer audio, there is an audio version of the video in the next section. And below that there is an edited transcription that you can read. In the Intro to the Intro section that comes next, I share some additional thoughts. Intro to the Intro :)
Second Article
Why Do Charts Need to Be Calculated?
Watch now (6 min) | Notes I use the phrase “sync up” a number of times in the video \ audio. It’s not really the best term for what I’m trying to say. What we’re doing in chart calculation is converting a given time to another kind of time. That’s different than syncing.
Announcing the Astrology Journal Bookshop
Please note: For the course, I do not recommend that you buy books at this time. Also note that you can find used versions of the books that have all the information you need. Nevertheless, I am pleased to be able to offer the option below if it should ever make sense.
Bookshop.org is an online bookseller that was created to support independent booksellers. It is a certified B corp company. Proceeds from every book you buy support independent booksellers, which gets me excited.
Bookshop.org also has a robust affiliate program that allows people to open an online bookshop on their platform. When someone buys a book from a shop, 10% of the purchase goes into a pool to support independent booksellers, 10% goes to the affiliate shop owner, and 10% goes to Bookshop.org.
Thanks to Bookshop.org, I now have an online bookshop called Astrology Journal Bookshop* that allows me to share my book recommendations and support independent booksellers, Bookshop.org, and myself while I’m at it. The focus of my shop is astrology books and I will be adding more in the future. I may also include non-astrology books that help to broaden one’s understanding of the archetypes.
*Note that the link I provided above takes you to my shop. When you purchase a book from my shop, I receive a commission.
Here are three article reviews about Bookshop.org:
Positive
How Bookshop.org Survives—and Thrives—in Amazon’s World (Wired)
Bookstores Are Struggling. Is a New E-Commerce Site the Answer? (The New York Times)
Negative
Why Bookshop.org is not the saviour the book world needs (The Passive Voice: A Lawyer’s Thoughts on Authors, Self-Publishing and Traditional Publishing)
Update
11/30/2023: I discovered that pixabay’s license changed so I changed the cover image to align with their new terms.
Update (7/27/2023): I added the article thumb as an image so that I could better link the creator’s name with the creation.
Update (7/28/2023):
I made some minor edits to correct grammar and provide more clarity.
In the section, A Table of Houses, I explained that I talked about why we need the sidereal time in the previous article and provided a link to it.
Towards the end of the post, I included a link to the first article in the series in addition the previous (second) article.
I corrected a mistake. I meant century, not millennia regarding how many years ephemerides cover, though astro.com has ephemerides for every year for 9,000 years.
Notes
If you would like to get a sense of the house division topic, Wikipedia has a lengthy article on it called House (astrology). I cannot speak to its accuracy but it will introduce you to the topic.