Ishta Devata ~ How to Find Ishtadevata ?
Ishta Devata is the personal Deity who will guide the soul to its real home--Moksha. The key role in revealing one's Ishta Devata plays the Atma Karaka. Atma Karaka is the planet that has the highest longitude. To find one's Ishta Devata we have to look at the Atma Karaka in Navamsa, since the Navamsa shows blessings of God onto the native and the way in which the native communicates with God. Navamsa is also known as the dharma-amsa, since it is the 9th division (9th house signifies dharma). Therefore we should look for Ishta Devata in this Varga.
Atma Karaka in Navamsa is called the "Karakamsa". The 12th from the Karakamsa determines the "Istha Devata". The 12th house from the karakamsa is called the "Jivanmuktamsa". This is the house signifying the emancipation of the soul and we have to examine this house in order to find one's Ishta Devata. If there is a graha in the Jivanmuktamsa, it signifies the Devata. If there are more grahas than one, we choose the strongest. If there is no graha in the Jivanmuktamsa, you can see whether any Grahas are aspecting the 12th. If no Grahas aspect it, you can take the 12th Lord as Ishta Devata.
In the chapter called "kaarakaamsa phala" in BPHS, Parasara mentioned the deities worshipped based on the planets in the 12th from kaarakaamsha. For example, Sun in 12th from AK shows a worshipper of Shiva and Moon in 12th from AK shows a worshipper of Gouri. Here are the presiding deities for each planet who will be your Ishta Devata as per your horoscope.
Sun~ Vishnu/ Rama/ Shiva
Moon ~ Krishna/Parvati
Mars ~ Hanuman/ Subramanya/ Sri Narasimha
Mercury ~ Vishnu
Jupiter ~ Vishnu/ Sri Vamana/ Dattatreya/ Sai Baba
Venus ~ Mahalakshmi/ Parashurama
Saturn ~ ShaniDev/ Hanuman/ Kurma
Rahu ~ Durga/ Varaha
Ketu ~ Ganesh/ Matsya
Ascendent ~ Kalki
Everyone is eligible for the worship of one's Ishta Devata and everyone at least should know their Ishta Devata. The process of worship is simple and is based on the chanting of the Dvadakshari Mantra for the appropriate Devata. An examplary Dvadakshari Mantra for Lord Vishnu as Ishta Devata is given by the Parashara Sage in his Vishnu Purana as follows: om namo bhagavate vasudevaya
In the given example chart Mercury is the AK. Its is placed in Pisces in Navamsa Chart. 12th from AK is Aquarius. As no planet is placed in Aquarius take the lord Shani. So his Ishta Devata would be Shani Dev. This native is a great devotee of Shani dev and Lord Hanuman. Saturn is with mars and mars also aspecting 12th from Karakamsa.
OM TAT SAT