Is synastry even accurate without birthtimes?I specialize in Synastry Aspects.
It is very possible to get near accurate Synastry aspects without birthtimes of either party. I have done it and can do it. But, it is best to have the correct birthtime for at least yourself. This helps your Synastry chart to be accurate for at least you and with only some degree of error for the other person, provided, you use a 12 noon birth time for the other person. This is because, the Moon moves approximately 6 degrees per day - 12 noon places the Moon at the half way point. This places the other person's Moon in a fair position of correctness relative to the unknown time of birth. If you use this method, then using a pie chart is not required.
I have been able to use one person's birthdate to identify who the compatible birthdays may be without the use of pie charts. If you like, take a peek of any one of the several I have serviced in Linda Goodman.
http://www.linda-goodman.com/ubb/Forum11/HTML/003265.html
http://www.linda-goodman.com/ubb/Forum11/HTML/004238-2.html
http://www.linda-goodman.com/ubb/Forum11/HTML/004238.html
http://www.linda-goodman.com/ubb/Forum11/HTML/003820.html
http://www.linda-goodman.com/ubb/Forum24/HTML/214475.html
http://www.linda-goodman.com/ubb/Forum11/HTML/003892.html
http://www.linda-goodman.com/ubb/Forum11/HTML/003191.html
http://www.linda-goodman.com/ubb/Forum11/HTML/003483.html
http://www.linda-goodman.com/ubb/Forum11/HTML/004004.html
http://www.linda-goodman.com/ubb/Forum24/HTML/213909.html
http://www.linda-goodman.com/ubb/Forum11/HTML/003409.html
The method I use to find these dates is with the Colorvision Synastry Aspecting Chart.
http://www.linda-goodman.com/ubb/Forum24/HTML/222353.html
slowpoke