 ## Gyalpo Losar # Calculation for Gyalpo Losar

One of the dates that is calculated for each year of the Tibetan lunar calendar is the gyalpo losar or the royal new year. In general, Tibetan mathematics requires a lot of effort to understand it. And if look at the calendars, then every year we can come across amendments related to the calculation of calendar dates, as well as knowledge of losar and other parameters of the previous year. All this seems relatively hard to understand, especially if a person is just starting to study Tibetan astrology and is trying to build calendars, relying on tracts. It is also necessary to take into account that Tibetan calculations may initially contain an additional error, which is already initially embedded in the calendar. And it makes you suffer a lot of misunderstanding when you try to make a calendar.

Is it possible to avoid all these troubles? Yes. To do this, we need to determine several basic values, and also we can proceed to the use of modern methods of computing related to astronomy, especially since there are a lot of astronomical calculators now.
So. What requirements can we have for calculations?
1 - the presence of a certain base date.
2 - the presence of a certain value, which is not subject to change

For the initial date we will take December 21 -991. This date (as opposed to 1023 or 1026) corresponds to some parameters, which so far in the article will not be indicated. Theoretically, the base date to start calculations can be rolled back into the past for several thousand years.
The second. For a certain constant value, we take the period of the orbital rotation of the moon, equal to 29.530588. This value does not change very much, so it can serve well for our purposes.
Now we give the procedure for calculating the Losar for example for 2019. The calculations use values ​​that can be found using various astronomical algorithms or calculators presented on the network. Therefore, we will not disclose them.
So. What is the procedure for settlements?
1. Define the modified Julian date for the base date. It will be equal to -1040550.3932.
2. Choose a date for preliminary determination of the number of months elapsed since the beginning of the reference period.

For the initial date we will take December 21, minus 991. This date (as opposed to 1023 or 1026) corresponds to some parameters, which so far in the article will not be indicated. Theoretically, the base date to start calculations can be rolled back into the past for several thousand years.

The second. For a certain constant value, we take the period of the orbital rotation of the moon, equal to 29.530588. This value does not change very much, so it can serve well for our purposes.

Now we give the procedure for calculating the Losar for example for 2019. The calculations use values ​​that can be found using various astronomical algorithms or calculators presented on the network. Therefore, we will not disclose them.
So. What is the procedure for settlements?
1. Define the modified Julian date for the base date. It will be equal to -1040550.3932.
2. Choose a date for preliminary determination of the number of months elapsed since the beginning of the reference period.
Best of all for any year is the date when there is definitely no losara. This date can be any date starting from the first of May and up to the first of November.
Take as an example May 1, 2019 and determine the modified Julian date. It will be equal to: 58603.83333
3. Next, we need to determine the number of days elapsed from the base date.
58603,833333 - (- 1040550,3932) = 1099154,226533
4. Determine the number of past months from the starting date (the number of periods of the Moon's circulation), select the integer part and add to the given number 1.
1099154,226533 / 29,530588 = 37220.87167 or 37220
37220 + 1 = 37221
5. Determine the number of months that can be considered double. To do this, divide by 33.5, subtract 0.02 (error found) and select the whole part
37221 / 33.5-0.02 = 1111.05462 or 1111
6. Remove the number of double months from the calculation, leading to the usual calendar of 12 months
37221-1110 = 36110
7. Determine the number of possible past years. Divide by 12 and take the whole part.
36110/12 = 3009.166666 or 3009
8. Determine the number of past months.
3009 * 12 = 36108
9. Determine the shift by month.
36110-36108 = 2
10. Subtract the shift from the value obtained in paragraph 4.
37221-2 = 37219
11. For the obtained value we repeat the calculations made in paragraph five.
37219 / 33.5-0.02 = 1110.99492 or 1110
12. If the obtained value coincides with that obtained in paragraph 5, then in the interval from the possible beginning of the year to the date from which it was considered - an additional month was not.
If it does not match, then we must subtract 1, which we do.
37219-1 = 37218.
13. Now we determine approximately the date of the occurrence of the Gyalpo Losara.
-1040550,3932 + 37218 * 29.530588 = 58519.030984
14. With the help of astronomical calculators determine the date of the Gregorian calendar.
We get the fifth of February 2019.
15. Determine the nearest new moon to this date.
2019 February 4 21:03 (UT).
16. Since we are now making calculations for Moscow, we must also find out when this event came in Moscow. Since we have a third time zone, we get
2019 February 5 0:03
17. From the point of view of Tibetan astrology, an event refers to a particular day if it is in the range from morning civil twilight to the next morning civil twilight.
Civil twilight time 7:36. That is, the event (new moon) does not apply to this day. and this day is a new lunar day. And as a matter of fact - the comer debris.

As you can see, this sequence of operations is not difficult to execute. All mathematics has been tested on the current Rabjung and coincides with all calculations of Lozars. Of course, to determine other types of lozar (Phugpa, Bon, Rebkong), it is necessary to introduce some minor adjustments. We will talk about them in the next article.