Software Updates and ACS Atlas History
ACS and Solar Fire Updates Available Now

Currently, there is an update for both Solar Fire 9 and the ACS Atlas posted at our website. It is highly recommended that you update both programs. You can do that here:  

The ACS Atlas update can also be used for v. 8 of Solar Fire. However, it is not usable in prior versions. If you own an older version of Solar Fire (7 or earlier), we recommend that you upgrade your software here: 

When future updates are posted to either the Atlas or Solar Fire 9, we will use this email list and our Facebook group to inform you. 

Below is a history of the atlas and our methodology for making changes to the atlas.

The History of the ACS Atlas

Prior to the widespread use of computers, few except astrologers had any interest in putting together detailed information about the time standards that were actually in use in different geographical areas at various times in history. 

Neil Michelsen saw the need for accurate time change and zone information and became the modern center of efforts to make a truly comprehensive Atlas for astrologers. He originally undertook this project in order to facilitate his computerized astro chart service. Much of the research for the time zone information contained therein was done by Thomas Shanks, Mark Pottenger and his brother Rique building on the source work of the early pioneers.

The major early sources for time changes were the pioneering works by Doris Chase Doane (Time Changes in the USA) and Curran and Taylor (World Daylight Savings Time). To this base were added the results of primary research, such as Eugene Derney who compiled the latitude and longitude information that underlies much of the modern work and Tom Shanks and others who researched the history of time changes at local libraries using newspaper microfilm collections.  Also, a collection of The Official Guide of the Railways of the United States was incorporated into the atlas providing a wealth of time change information. With regard to the ACS International Atlas, the major work was conducted by Francoise and Michel Gauquelin. In addition, other astrologers and non-astrologers contributed and, indeed, continue to contribute to the database of international time change and time zone information. 

In addition to Doane, Derney, and the Gauquelins, many individual astrologers willingly shared their information with Neil's team so that the entire astrological community could benefit from its publication. Without their groundbreaking work, we would not be able to reliably cast charts for many smaller places in the world. And, just about every time zone database that exists today has used the information originally published and copyrighted by Michelsen as a starting point.

Eventually, the ACS PC Atlas software was created from the 1980's database from which the books were published. In 2008, Astrolabe took over the maintenance of the Atlas from Maria Kay Simms, the current owner of ACS Publications. We inherited a program that is both difficult to maintain and written in ancient code, so ancient that younger programmers have no clue where to begin. We have spent countless hours and a great deal of money (think in the 6 figures) in order to transition this very complicated program and its extensive database into something more manageable and easier to maintain without losing the more nuanced and hidden data embedded into the data streams. Otherwise, Astrolabe would have created a simple database. We believe the integrity of the data is integral to this project. That work continues through the efforts of Bart Lidofsky. 

A Community Project     

The ACS Atlas has always been and continues to be a collaboration among astrologers and is considered a work in progress. Even as I write this, time changes for Argentina are being researched by staff and, if necessary, will be incorporated into the atlas. 

We often hear comparisons of the data in vs ACS Atlas. When we are talking about clock transitions prior to 1970, has this disclaimer on their website:

"Clock transitions before 1970 are recorded. However, the database is not designed for and does not suffice for applications requiring accurate handling of all past times everywhere, as it would take far too much effort and guesswork to record all details, of pre-1970 civil timekeeping."

While is not reliable for pre-1970 information, they can be a better resource for post-1970 changes. Even currently they do not try to be accurate for small areas that diverge from "standard" time rules and give the standard government proclamations for time rules, even if the populace does not follow them. Please note that we monitor the changes to their database on a regular basis and the reason for the change as well. Such changes, if they meet our high standards of well-researched and reliable, are then incorporated into the atlas. 

Before we make a change to the historical data in the ACS PC    Atlas, we require two corroborating pieces of information of a high reliability, i.e. original sources. For example, newspapers of the time in question are a good source. Lacking this information, the current data will not be changed. Just this week, we received such information about Burlington Ontario from an astrologer in Canada and this too is being reviewed. Lacking this information, the current data will not be changed.

If you have concerns or questions about a particular date/time/place or if you have a change to the historical information and the corroborating evidence as we explained above, please do not hesitate to email who will review your information. We take the accuracy of the atlas as seriously as you do and we will make every effort, with your help, to update the atlas as needed. 

This is astrology's collective work and Astrolabe is only the current caretaker for this unique and fundamental work. The community should be proud that your collective contributions have shaped not only astrology but also the underpinnings of the World Wide Web that we all depend upon.

Thank you for all the support through the years,

Team Astrolabe

Astrolabe | | 1-800-843-6682 |
See what's happening on our social sites: