13
Ursa Major wrote:
Fleur wrote:Why am I getting a different chart when I enter that date and time into Astrodienst? I am getting Sun 6 degrees Leo 55 minutes, Moon 0 degrees Virgo 08 minutes and Ascendant 2 degrees Sagittarius 52 minutes.
Fleur,

Is is a Julian date not Gregorian !!
There is more than a 4 degree difference in the Sun's position, ie more than 4 days, between the Julian date and the Gregorian. The Sun in the chart above is 10 degrees Leo 48 minutes, and the chart when you enter that date into Astrodienst's chart calculator is 6 degrees Leo 55 minutes.

This discrepancy has nothing to do with the Julian v. Gregorian calendars.

14
Fleur wrote:
This discrepancy has nothing to do with the Julian v. Gregorian calendars.
Well, it does I think. When Julius Ceasar brought in his calendar in 46 BC, the start of the year was at the right place. But by 1582 when Pope Gregory brought in his reforms to the calendar, the error in the Julian calendar had resulted in a ten day slip in the start of the year. So, part of the reforms in changing over to the Gregorian calendar was to simply fast-forward ten days to put the calendar back on track.

But that was in 1582. If the Gregorian corrections had happened at a date half way between 46BC and 1582, then you would only have needed half as much correction....

Re: Foundational Chart for Baghdad

15
Geoffrey wrote:
delaforge wrote: Am I missing something?

Melissa
No, I don't think so. I think the conclusion of the paper is that the Al-Biruni chart gives the right day and time. Modern software can make up deficiencies in planetary positions, which we not expect a chart from the 8th century to have exactly right.
But that doesn't explain why the 'modern' positions are incorrect too.

Have the 'modern' positions perhaps been calculated by the same means Biruni would have used? That would explain the discrepancy.

Melissa

16
Fleur wrote:
Ursa Major wrote:
Fleur wrote:Why am I getting a different chart when I enter that date and time into Astrodienst? I am getting Sun 6 degrees Leo 55 minutes, Moon 0 degrees Virgo 08 minutes and Ascendant 2 degrees Sagittarius 52 minutes.
Fleur,

Is is a Julian date not Gregorian !!
There is more than a 4 degree difference in the Sun's position, ie more than 4 days, between the Julian date and the Gregorian. The Sun in the chart above is 10 degrees Leo 48 minutes, and the chart when you enter that date into Astrodienst's chart calculator is 6 degrees Leo 55 minutes.

This discrepancy has nothing to do with the Julian v. Gregorian calendars.
It does !

If you enter this in Astrodienst you have to enter as year 762 jul. and with the time 14h 30m . Then you will have the right chart.

17
But that was in 1582. If the Gregorian corrections had happened at a date half way between 46BC and 1582, then you would only have needed half as much correction....
That is my understanding too
"The universe is full of magical things, patiently waiting for our wits to grow sharper" Eden Phillpotts