Calculating Daylight Savings Time?

[mike3reynolds]

I've found GeoNames, a database of two million cities with long, lat and timezone, but I need to take it a step further and calculate when DST begins and ends. I know this is the biggest challenge facing my desire to automate online chart making. Does anyone know how I would start to address this issue? I know there use to be two books on calculating Time Changes, one was for the US and the other was for world countries.

(P.S. I want to do this in order to create an astrology match making website.)

[waterbird]

mike3,

Before I bought a program I used The International Atlas. There were two, one for USA and one for the rest of the World.

water bird

[saturn]

Good luck - this is an area that seriously needs help.

There is no decent atlas out there that is available for free. The "old" ACS atlas was taken over by www.alabe.com, but they have been working on an updated version for many, many months and it is still not ready for licensing. If you want to go the brute force method, then here is a website that can help you with the information (but it will be a HUGE job for you to collect all the relevant data):

http://www.timeanddate.com/time/dst/2010.html (back years are available)
http://www.timeanddate.com/time/dst/2010b.html
http://www.timeanddate.com/news/time/

I heard once that www.astro.com wanted to produce an open source DST database, but does not yet have the rights/etc. in order to be able to do it. I wish AstroDienst would/could buy the rights from Astrolabe. Maybe some day. So you are sort of stuck for now.

[mike3reynolds]

I went through all the books at http://alabe.com/books.html, but I couldn't find the ACS atlas you are talking about.

[saturn]

http://astrocom.com/products/book.php?book_id=b110x - American atlas

http://astrocom.com/products/book.php?book_id=bia6e - International atlas

These are the books that need to be "reproduced" in a MySQL database for all to use (some day).

Trust me - it is a HUGE job unless one starts with the existing ACS atlas, which legally cannot be done at this time.

[mike3reynolds]

Has anyone looked at cafeastrology.com's natal chart maker?
http://astro.cafeastrology.com/cgi-bin/astro/natal

It gets my ascendant right and I was born during DST, so I know it is working for some cases.

At this very early point in the development of my website I would be happy with just the most common pattern for when DST starts and ends in the US, which is what cafeastrology.com does, I suspect.

[Noel Tyl]

  Mike:

Before computers, all knowledge about time changes was the astrologer's responsibility.  The giant achievement of recording all time changes in the nation was accomplished by Doris Chase Doane.

Her "Time Changes in the USA" [Perhaps still available from the AFA in Tempe AZ] was/is vitally important.

Every state is covered from when the area was first settled!  All DST date-periods are recorded.

In short, you need this book.  It will solve all your problems ... I think!

Noel Tyl

[Sternleser]

Mike3reynolds:
Be careful of "cafeastrology" chart maker.
It insists that I was born during DST.
I was not!
I also have checked it with other dates in my data base,
and at times it gets it correct and other times it is off.
So far I have never found Astrodienst to be wrong.
I use that site if I am not sure.
Dave

[Ray Murphy]

I've found GeoNames, a database of two million cities with long, lat and timezone, but I need to take it a step further and calculate when DST begins and ends. I know this is the biggest challenge facing my desire to automate online chart making. Does anyone know how I would start to address this issue? I know there use to be two books on calculating Time Changes, one was for the US and the other was for world countries.

(P.S. I want to do this in order to create an astrology match making website.)

Facts (or things that are purported to be facts) cannot be protected under any
copyright law. It's only the formatting of them that can be, but only if it's done
right. It also pays to keep in mind that while copyright protection may be claimed,
it may not necessarily exist - for example if someone claimed they had a unique
formatting style for a batch of facts and they didn't want anyone using that same
style, then only a court could decide.


Another interesting thing for astrologers is that copyright can only be claimed on
astro-fiction, ideas or speculation etc. - not standard astrological teachings - which
are regarded as facts.

[mike3reynolds]

  Mike:

Before computers, all knowledge about time changes was the astrologer's responsibility.  The giant achievement of recording all time changes in the nation was accomplished by Doris Chase Doane.

Her "Time Changes in the USA" [Perhaps still available from the AFA in Tempe AZ] was/is vitally important.

Every state is covered from when the area was first settled!  All DST date-periods are recorded.

In short, you need this book.  It will solve all your problems ... I think!

Noel Tyl

That's the book that I remember! Thank you very much, I found it on Amazon for $10.