What it does
Times the worship, havan and mantra of each devta for the fastest activation.
Where
At the pad of the devta being worshipped
When
Shikhi: the period ending at 3:00 am, before sunrise. Parjanya: 3:00 to 3:45 am. Shikhi and Parjanya stay awake through the Shravan month.
Explanation and notes
32 periods of 45 minutes make 24 hours, so the outer devtas return to the same time every day; the cycle is counted from 3:00 am to 3:00 am.
Shikhi, also called Shiva, is the first outer devta of the pishach bhoomi, at E1 near the North-East corner. A mahayogi and a highly sensitive maha-dowser, its pad reacts at once to anything done there; it governs vision, foresight and decisions.
Parjanya, the cloud and rain devta (megh, badal) at E2 next to Shikhi, brings rain, productivity and fertility and fulfils plans and wishes like a kalpavriksha. It is the doctor of crops, people and animals.
A quick manual method to divide any plan into the concentric bhoomis of the 81-pada grid by multiplying the centre-to-corner distance by 0.33, 0.55 and 0.77.
After the bhoomi rings are drawn, the outer ring is cut into 32 pads of 11.25 degrees each, starting with Som devta centred on North, and the middle ring into 12 inner pads with an 18-54-18 degree split for each direction.
During Shiva's battle with Andhakasura a drop of his sweat produced a starving mahabhoot; devas and asuras laid him face down and 45 devtas sat on him, creating 45 places with separate functions on every plot. Brahma made him his manas putra and promised that whoever occupies land would remember and feed him.
Both grids hold the same 45 vastu devtas, but the 81-pada mandala is used for homes and business premises while the 64-pada mandala is used for temples, villages, palaces (raj mandir), towns and city gates.
The biggest pooja, havan and sthapana of the 45 devtas should be done at garbh vinyas or shilanyas, while the devtas are on open ground and can receive their samagri at their own pads; the building is then raised over them.
In earlier times, after garbh vinyas and the plinth beam, builders left the work for a season of about three months so that the sun, moon, 27 nakshatras and 9 planets could fully act on the newly acquired and worshipped land.