Yoga and karana are the two Panchang limbs people know least, but both appear in every almanac and both matter when choosing a time.
Yoga
Here "yoga" does not mean the exercise. It is the combined position of the Sun and Moon: their longitudes are added together and the result is divided into 27 equal parts. Each part is one yoga, lasting roughly a day.
Most yogas are favourable. Nine are traditionally avoided for new beginnings: Vishkambha, Atiganda, Shula, Ganda, Vyaghata, Vajra, Vyatipata, Parigha and Vaidhriti. Vyatipata and Vaidhriti are considered the most severe.
Some of the best-known good yogas are Siddhi, Siddha, Shubha, Saubhagya and Shobhana.
Karana
A karana is half a tithi, so there are two karanas in each lunar day. There are 11 karanas in all:
- 7 movable karanas that repeat in a cycle: Bava, Balava, Kaulava, Taitila, Garaja, Vanija and Vishti
- 4 fixed karanas that occur once a month around the new moon: Shakuni, Chatushpada, Naga and Kimstughna
Bhadra (Vishti karana)
Vishti, also called Bhadra, is the one karana everyone watches. It is considered unfavourable for ceremonies, travel and new ventures. Festivals such as Raksha Bandhan and Holika Dahan are specifically timed to avoid Bhadra. Because a karana lasts around 12 hours, Bhadra can cover a large part of a day.
Rekha lists Bhadra under "Avoid today" whenever it falls in your day.
How yoga is calculated, with an example
Suppose the sidereal Sun is at 175 degrees and the Moon at 200 degrees. Their sum is 375 degrees, which wraps around to 15 degrees. Each yoga spans 13 degrees 20 minutes, so 15 degrees falls in the 2nd yoga, Priti. When the sum passes 26 degrees 40 minutes, the yoga changes to Ayushman.
The 27 yogas in order
Vishkambha, Priti, Ayushman, Saubhagya, Shobhana, Atiganda, Sukarma, Dhriti, Shula, Ganda, Vriddhi, Dhruva, Vyaghata, Harshana, Vajra, Siddhi, Vyatipata, Variyana, Parigha, Shiva, Siddha, Sadhya, Shubha, Shukla, Brahma, Indra and Vaidhriti.
How karanas repeat through the month
The first half of Shukla Pratipada is always Kimstughna. After that the seven movable karanas repeat in order (Bava, Balava, Kaulava, Taitila, Garaja, Vanija, Vishti) eight times. The last three halves of the month, around Krishna Chaturdashi and Amavasya, are Shakuni, Chatushpada and Naga.
Bhadra and festivals
Because Vishti returns every few days, festival timings often depend on it. Raksha Bandhan rakhi-tying is done after Bhadra ends, and Holika Dahan is performed in the evening when Bhadra is not active. If Bhadra covers the whole evening, almanacs use special rules, which is why Holika Dahan times sometimes look unusual.