The Zodiac is divided into 12 equal parts and each division is called Rasi or Sign or Solar Mansion. These are Aries (Mesha), Taurus (Vrishabha) so on till and Pisces (Meena) and each measuring 30 degrees.
The Hindu or Vedic astrology has another division. In this division, the Zodiac is divided into 27 equal parts each measuring 13-20 degrees or 13 degrees and 20 minutes. (The equivalent decimal degrees will be 13.333.)
These 27 divisions are called as Lunar Mansions or Nakshatras or Asterisms or Star Constellations.
These 27 Lunar Mansions are named as – Ashwini, Bharani, Krittika, Rohini, Mrigashira, Ardra, Punarvasu, Pushya, Ashlesha, Magha, Poorva Phalguni, Uttara Phalguni, Hasta, Chitra, Swati, Vishakha, Anuradha, Jyeshtha, Moola, Poorva Ashadha, Uttara Ashadha, Shravana, Dhanistha, Satabhisha, Poorva Bhadrapada, Uttara Bhadrapada and Revati.
So from 0 to 13.333 (decimal degrees, otherwise would be 13 Deg. and 20 Minutes), it is Ashwini. From 13.333 to 26.667 it is Bharani and so on.
Each Nakshatra is again divided into 4 equal parts of 3 deg. and 20 minutes (decimal equivalent will be 3.333). Each part is called as Pada or Quarter. In another post, this topic will be discussed, later, with the help of proper images.
9 planets have been given the lordship of these 27 Nakshatras. In other words, we can say that the 9 planets have influence on these 27 Nakshatras. The order of lordship is as follows-
Ketu (South Node), Venus, Sun, Moon, Mars, Rahu (North Node), Jupiter, Saturn and Mercury.
So the first 9 Nakshatras will be ruled by the 9 planets, in the order mentioned above. Then from 10 to 18 Nakshatras, again the lordship will be in the same order. And from 19 to 27 Nakshatras, again the lordship will be in the same order.
So the 1, 10 and 19 Nakshatra will be ruled by Ketu (South Node). In other words, Ashwini, Magha and Moola are influenced by Ketu. 2, 11, 20 (i.e. Bharani, Poorva Phalguni and Poorva Ashadha) will be ruled by Venus. And so on.
Now the Solar Mansion, Aries which measures 30 degrees contains Ashwini (13.333), Bharani (13.333) and one-fourth of Krittika (3.333 or 1st Pada or 1st Quarter). The remaining 3/4th of Krittika will be in the Solar Mansion Taurus. So the Taurus will have Krittika (10 deg or 2nd, 3rd and 4th Padas or Quarters), Rohini (13.333 deg i.e. complete) and half of Mrigashira (6.667 deg or 1st and 2nd Padas or Quarters). In this way the Lunar Mansions are allotted to Solar Mansions.
The 1/3rd of the Zodiac i.e.; 120 degrees (first 4 signs; Aries, Taurus, Gemini and Cancer) are allotted first 9 Lunar Mansions. Leo, Virgo, Libra and Scorpio will get next 9 Lunar Mansions. And from Sagittarius to Pisces will get last 9 Nakshatras.
These Lunar Mansions or Constellations are either a group of stars or a single star. More information can be found here - https://en.wikipedia.org/wiki/Nakshatra
As I always say, A Picutre Is Worth Thousand Words... Right... ?
BTW, here after I will be using a common term for these Lunar Mansions, Asterism or Constellations and it will be Nakshatra.
In the above image, you will see that, there are dashed horizontal lines denoting the starting degrees (Ingress Point) each Nakshatra. Also you will see 3 dashed lines are identical in color, denoting the lord ship of a particular planet. Exception is the 0 (zero) deg line.
Below image is of NIFTY with Sun Ingress in these 27 Nakshatras.
Below image is of NIFTY with Mercury Ingress...
Below images are of Crude (MCX) with Saturn and Rahu (North Node) Ingress...
To be contd...
Note: The longitudinal degrees are Sidereal (Niryana).