http://1.As  many of you know, an ephemeris only tabulates the planet’s positions at one time of day. Thus, what are you to do when you want to find where a planet is at an intermediate time?

(Tl;Dr: Linear interpolation)

2. Now, I must admit the method I shall describe in this thread is more-or-less obsolete. Websites and apps can cast whole charts with absolute accuracy in seconds. But this method formed the base of all astrological calculation right up till computers were invented.

3.The method is rather simple. It is based on the fact that the planets travel at a roughly even speed throughout the day. If you know [say] that the Moon travels 12 degrees in 24 hours, she travels 6 degrees (half of 12) in half a day, or a 3 degrees in a quarter of a day

4.Thus, by adding or subtracting the distance in the moon travels in so many hours or minutes to the midday time, you can predict where she shall be after so many hours or minutes.

http://5.Here ’s an example using nice round figures. Suppose you knew the Moon’s daily motion (12 degree per 24 hrs) and the fact that she was at 10 Aries today, at midday.

Now, If someone asked you “where would the Moon be at 1 PM today?” this can be put into action

6.Since the moon travels 12 degrees in a day, and the time is 1 hour after the tabulated time, you do two things.

First you find the amount the Moon travels in 1 hour. You do this by dividing the daily motion (12 degrees) by 24 hours, so you get 0.5 degree an hour

http://7.Next , you add this figure to the tabulated position: so, 10 Aries + 0.5 degrees= 10.5 Aries or, to use the modern term, 10Ari30. This is where the moon shall be at 1 PM.

8. In reality, the numbers are never so nice and round, and there are quirks to ephemerides. Let's give a practical eg.

To do this, you first need two things:
I: A given time and date you want to calculate – say your birthday
ii: The ephemeris for that day.

http://9.As  for the time and date of that day, you must know the time zone it is in. The Latitude is not necessary for this calculation.

10.The part about the ephemeris can be solved easily. http://Astro.com  offers ephemerides, which you can customize to the timezone required. The steps for doing so are here:

https://twitter.com/edwardW2/status/1278213470047989761
This cuts out a lot of trouble.