An astrologer needs the birth time to an accuracy of 2 min to create the 60 Varga subdivision chart. However, an astronomer needs to detect planet movements to a 0.5 degree granularity. For example, the moon can move 0.5 degrees in about an hour or two Ghatikas. Astronomers could make an observation at 2 Ghatika intervals. They also took the help of formula based tables.