panchag.py

# https://www.tifr.res.in/~vahia/tithi-calculations.pdf
import datetime
from astropy.coordinates import get_body
from astropy.time import Time
from astropy.coordinates import EarthLocation

NUM_TITHIS = 15

def get_tithi(timestamp, location):
  sun = get_body('sun', timestamp, location)
  moon = get_body('moon', timestamp, location)

  # TODO: Add the correction constant from the paper
  diff = sun.position_angle(moon).degree
  paksha = 'કૃષ્ણ' if diff > 180 else 'શુક્લ'
  tithi = (int(diff)) % NUM_TITHIS
  return (tithi, paksha)

if __name__ == "__main__":
  now = Time(datetime.datetime.now())
  location = EarthLocation.from_geodetic(lon=72, lat=23, height=0)

  tithi = get_tithi(now, location)
  print(tithi)