Sudarshana Chakra versus Graha-Chakras
Houses have been rotated in Kundalee Software to make SK (Surya Kundali) and CK (Chandra Kundali), but Lagna is not the cusp of that house in which Sun or Moon lie in SK or CK respectively. In SK, Sun is the lagna, and in CK, Moon is the lagna. If Lagna in CK is Vrishchika's last degree where Moon lies, why the next house should be approximately 30 degrees from cusp of Moon's house in LK because that will make difference of 2nd cusp too large from lagna which is Moon. Therefore, I added 30 degrees progressively to make cusps of other houses in SK and CK. I am not satisfied with this scheme, but I am hesitant with what is the logical alternative : to make each 7 planets LAGNA respectively and compute their bhaavachalitas from the basic equations. It will make eight ellipses in the sky instead of one. That sounds bizarre, but so is the concept of shodasha-varga. If 9th part of a rasi in D1 can be inflated to make one whole rasi in D9, we can digest many such apparently illogical concepts. Jyotisha is not logical if human logic is the criterion of logic. Hence, the criterion of truth in Jyotisha must be correctness of the phalaadesha and not the fallible and inconstant human logic.
Read the last portion of Varga-vivechana-adhyaaya in BPHS (Brihat-Parashara-Hora-Shastra) which states that in all vargas we ought to make a SC (Sudarshana Chakra) with eight chakras, one LK (Lagna Kundali) in which all 12 bhaavas will be significant, but other planets taken as lagnas in their charts in which only a few bhaavas will be significant. CK (Chandra Kundali) has five houses (1-2-4-9-11th houses from Moon ) significant, SK (Surya Kundali) has three significant houses, hence LK+CK+SK being most important in SC, but Saturn has two significant houses and other four planets have one each. If we take all twelve houses in SK and CK to be equally significant, we will find wrong phalaadesha in many cases. This point is missed by astrologers.
In this scenario, I think we should include all seven planets in SC with due weightage to their significant houses only.
How to Compute Surya Kundali and Chandra Kundali
Surya Kundali (SK) or Chandra Kundali (CK) do not change the longitudes of planets. Hence the lord of a planet will not be changed. But Bhaava-madhyas of SK and CK are sometimes different from those in LK (Lagna Kundali), because SK and CK are made differently. Here is the method I use for constructing SK and CK :-
Convert the decimal bhaava position of a planet into integers. Eg, if a planet is in 7th house and 10% before bhaava middle, its decimal bhaava will be 6.400 (decilam bhaava 7 means end of 7H). Then, remove the fraction and get the integer, which means 6 houses have elapsed and the planet is in 7H.
Then, substract this integral bhaava of Sun from the integral bhaava of the planet in question, you will get the bhaava of that planet in SK. In this way, you can compute houses in which all planets are planets in SK and CK. But uchchaadi strengths, aspects on planets and placements in signs will not change. Only the aspect on houses will change, because the houses have changed. For instance, if 10H in SK is 3H in LK, you should read the aspect on 3H in LK to be used for 10H in SK. That is why I did not provide separate aspect tables for houses of SK and CK. Unfortunately, astrologers are not using these features of Kundalee software because they do not use SC which is INDESPENSABLE in the absence of DAC (Dashaa Arambha Chakra). In 99.9% of cases, you will never be able to make correct DAC due to time constraints, and therefore SC is a must.
SCD (Sudarshana Chakra Dashaa)
BPHS explains SCD in clear language. In first year of birth, MD (Maha Dashaa which is annual) of SCD of Lagna or first house starts from date and time of birth. In second year, SCD-MD of second house starts. And so on. This rule applies to all divisionals.
One year starts from birthday and lasts for 360 degrees of Sun. Second level of SCD is Maasa-lagna which lasts for one solar month, ie, 30 degrees of Sun. In monthly SCD, first month's dashaa is same as the annual (ie, MD) SCD, second month;s SCD is of the next house, and so on.
Third level of SCD is called Pratyanatara or Vidashaa and has a duration of 2.5 degrees of Sun. First Pratyantara is same as the monthly SCD, next Pratyantara is of next house, and so on.
Kundalee Software has two more levels of SCD , decreasing in duration by a factor of 12 in each level.
At the onset of all these SCD dashas, five levels of VPC (Varsha Pravesha Chakrts) charts should also be made, which are actually Dashaa Entry Charts of SCD and may be called Varsha-phala charts as well.
After twelve years, the SCD's MD of first house repeats, but actual events in life do not repeat. Hence, SCD must be used in conjunction with Vimshottari &c, and sometimes common sense is also needed. Birth of offsprings should not be predicted if SCD of 5H commences when the native is only ten years old, for instance. There are some general rules of using SC and SCD described in BPHS which should be read carefully, and extraneous matter inserted by commentators, which have no link with original verses, should be ignored or used carefully.
Example of Using Sudarshana Chakra Dashaa
8H from a particular house is its Mrityu Sthaana. 8th from that Mrityu Sthaana shows the timing of that Mrityu of the chief topic of original house. For instance, 8th from Lagna is Mrityu of Deha (Deha = Lagna). 8th from 8H shows timing of Mrityu, ie, longevity.
In same way, 8th from 7H shows Mrityu or end of relation with spouse, hence 2H is house of second wife. 8th from 2H , ie, 9H, shows timing of second marriage or longevity of first marriage.
Here is one example :- my maternal uncle died when my D-1's SCD (Sudarshana Chakra Dashaa) was of :-
8H (MD of SCD),
2H (AD of SCD) and
11H (PD of SCD),
These houses 8H or 2H or 11H seen from my D-1's 6H made Lagna, ie, 8th from my D-1's 6H was Lagna of D-1 which had MD (Varsha-Lagna) in SCD. 6H is maternal uncles's house, and it should be made Lagna to judge events for maternal uncle. In that chart (6H made Lagna), 8H shows death of maternal uncle, 2H shows Maarakesha (killer) of maternal uncle, and 11H contained a malefic planet which was lord of 6H and therefore signalled illness.
Kundalee Software contains SCD table of all SCD-MD (ie, Varsha-lagnas of SCD), and all five levels of SCD for the Desired Date, which can be used to examine SCD for such events. Unfortunately, this use of SCD is not used now-a-days, although classics mention it, and BPHS, Bhrigu Samhita, Nadi granthas, etc contain innumerable instances of annual timings which were actually computed from SCD.
Munthaa and SCD (Sudarshana Chakra Dashaa)
Munthaa of Tajik Neelakanthee is exactly same as the sign of Bhaava whose SCD is running in annual or monthly or finer levels of SCD. It is noteworthy that the author of Tajik Neelakanthee was ignorant of Parashari Hora otherwize he would have noticed that Munthaa is same as SCD, although the latter was known to Varaha Mihira but not easily available as Varaha Mihira's commentator Bhatta Uptapa complained. The positive contribution of Tajik Neelakanthee lies in the fact that it examines the fruits of Munthaa according to its placement in annual (or monthly &c) charts, which is an additional use of Munthaa. But the drawback of Tajik is that it is ignorant of the basic meaning of Munthaa.
For instance, suppose your current annual chart's Munthaa is Mesha sign. In annual chart, suppose Mesha is the sign of cusp of 10H in annual chart. It means the overall fruits of planets in 10H and its condition of its lord plus relatives of lords will also affect the Bhaava of Mesha in birth chart. If the Bhaava of Munthaa in birth chart is 5H, then placement of Muntha in 10H in annual chart means that 10H and its effective planets will also affect the issues concerned with 5H in that year. This is the only significant importance of Munthaa in Vedic Jyotisha, rest of Tajik Neelakanthee is Islamic garbage imported into Vedic Jyotisha by ignorants like Neelakantha who had not read Parashari Hora. Another folly of Neelakantha was the use of Mean Sun for determination of annual or monthly returns of Sun, which is a serious error, because difference bewteen Mean Sun and True Sun may be uptu nearly two days, whereas annual charts need accuracy of lagna ! If we inspect the fuller method of SC and SCD, then all divisional charts must be used in annual charts, and therefore accuracy in determination of lagna in annual chart must be highly precise. The author of Tajik Neelakanthee was, therefore, a fool and worked with wrong annual and monthly charts. Some modern fools like Namichandra Shastri write that "Varshesha" was invented by Yavanas and was introduced into India by Tajik Neelakanthee! These fools never read ancient Siddhantic texts which mentioned Varshesha, Maasesha, etc, and BPHS also speaks of annual charts in SC chapter. There is no need to study foolish books like Tajik Neelakanthee. Just make the annual or monthly charts using precise solar returns, and use Suryasiddhantic Varshesha, BPHS SCD Bhaava (- Munthaa) and analyze the annual/monthly charts according to standard methods of BPHS &c, ignoring non-Vedic methods. Mixing incompatible systems into Vedic Jyotisha will prevent clear understanding of rishi-based method of Vedic Jyotisha. After you master the ancient techniques of rishis, you can experiment with extraneous methods and techniques.