Guru Pushya is Thursday in Pushya nakshatra, Ravi Pushya is Sunday in Pushya. Amrit Siddhi is a weekday in its own nakshatra (Sunday Hasta, Monday Mrigashira, Tuesday Ashwini, Wednesday Anuradha, Thursday Pushya, Friday Revati, Saturday Rohini). Sarvartha Siddhi is a weekday in one of its favorable nakshatras. Dwipushkar and Tripushkar fall on a Sunday, Tuesday or Saturday with Dwitiya, Saptami or Dwadashi tithi and a particular nakshatra; what is begun in them is said to repeat, so anything that could bring a loss is avoided. A weekday runs from sunrise to the next sunrise.
Times are local to London. A day runs from sunrise to sunrise, so a window after midnight belongs to the date above it.
Check a date against your own chart
These dates hold for everyone in the city. The Kaalvit app reads each one against a person's own Moon: chandra bala and tara bala across the window, with the reasons shown. Free on your own chart.
