Hello everybody,

Working on time standards to introduce a full user interface in A32v3, I went back to looking at the thread created by Martin Gansten more than a year ago (birth of Copernicus):

http://skyscript.co.uk/forums/viewtopic ... b249cb7349

I wrote something wrong:
Equation of Time calculators generally work with the Gregorian calendar, so you need to do a conversion first:
February 19, 1473 [Giuliano] → February 28, 1473 [Gregorian]

This creates confusion...

-1-
For ancient births, if the known time is the sundial time - LAT - , in Morinus "Local Apparent" must be selected. Conversely, if the time was already the local mean time - LMT - the choice must be "Local Mean".

-2-
It is only if you want to use the LMT starting from the older LAT, that E comes into play. Assuming that the source of the E calculation is reliable, we will use the well-known formula LMT = LAT - E and then proceed as in point -1-

And here is the correction to what I wrote then...

-3-
The calculation of E makes use of the Julian *Day*, and the Julian *Day* is calculated correctly by Morinus if you pay attention to select the right calendar in the birth data settings. Hence, Julian *calendar* or Gregorian *calendar*.

-4- Astrolog and Astrolog32 automatically switch to the Julian *calendar* (apart from the details on its date of adoption by the states back then), so they too calculate Julian *Day* correctly.
The only limitation for them is that at the moment they only work with hours according to the current standard of Time Zones. And it is on this point that we are working to insert in Astrolog32 also the old LST, LMT, LAT standards.

Roberto