When having an Astrological reading, your chart is constructed by using the city & state (or country) in which you were born, plus the month/day/year of birth and the birth time. If you are trying to obtain your exact time of birth, you will need to contact the vital statistics department in the state where you were born.

I recommend going to the following web site for US births and there is even information for other countries listed at the www.vitalrec.com site:
www.vitalrec.com

For those of you born in the U. S., when you go into this web site, simply click onto "birth", and when taken to this page, you then only need to scroll down to the state in which you were born. Click onto your state, this will take you to your state's page. The address and phone # for the department handling birth information in your state will be given and the fee amount.
Be sure when you make your request for your birth certificate, that you request that your birth time be put on the certificate. If you don't, it probably will not be shown!

You will then need to request the certificate again with the fee. (There is directions on the web site how to obtain information for births outside of the U.S.)