Gajachchhaya Yoga is formed by combination and concurrence of Sun, Moon and 2 tithis (Lunar Days) which are Trayodasi and Amavasya.
This yoga is formed when Sun transits through Hasta Nakshatra in Virgo (Kanya Rasi) once in a year and mostly during Pitru Paksha.
In 2021, Gajachchhaya Yoga occurs twice Trayodasi (3rd/4th October) on Amavasya (New Moon Day), which is 6th October.
Trayodasi yoga is not applicable in Asia and Europe, while Amavasya Yoga is not applicable in North and South America.
People in Europe, North and South American countries can utilise this yoga and offer prayers to their ancestors.
The combination when the Sun is in Hasta Nakshatra and the Moon is in Magha Nakshatra during Trayodasi Tithi of Pitru Paksha is known as Gajachchhaya Yoga, but this combination does not occur in 2021.
Next occurance of Gajachchhaya Yoga is when the Sun and Moon are in Hasta Nakshatra during Amavasya Tithi of Pitru Paksha is also known as Gajachchhaya Yoga.
So, there might be one or two Gajachchhaya Yoga during Pitru Paksha. This auspicious combination occurs either on Trayodashi Tithi or on Amavasya Tithi.
Gajachchhaya Yoga (गजच्छाया योग) does not form every year. But whenever Gajachchhaya Yoga occurs during Pitru Paksha, it is considered highly auspicious for performing Shraddha rituals and charity.
Transit of Sun in Hasta nakshatra happens every year during September-October. But this should be Bhadrapada Maasa (where fullmoon forms in Uttara Bhadrapada Nakshatra) and not adhika maasa.
Second half of this month (when Moon is waning between fullmoon to next newmoon) is called Mahalaya Paksha or Pitru Paksha and no auspiscious event is performed during these 15 days.
Traditional astrologers do not check any horoscopes and postpone all astrological advises.
These are the days to offer Shraddh to deceased ancestors in a family.
Pitru Dosha Causes, Effects & Remedies.
Curses of forefathers is said to cause pitra dosham according to puranas, but reality is that, one faces this only because of his/her past life deeds.
There are be millions of souls in this world who are not resting in peace. All the souls are ancestors of someone who are alive today.
But, reality is that Pitra devatas are not the one who are deceased, but the ones who are never born and will never die.
They reside in the form of DNA and continue that ‘Gotra‘ through ‘Y’ chromosome of males in that family.
When one person suffers from pitru dosha, his/her family will struggle to see next generation smoothly.
Either they will not have kids, or their children will seperate from them, or no male kids in next generation will end their Gotra.
In all Asian countries, Trayodasi Gajachchaya Yoga forms on 3rd October 2021 during night time (4th October in Australian Continent) and ends before or around sunrise, which makes it invalid for offerings.
For New Zealand Time Zone (GMT +7:30) : From sunrise till 10:56 AM (4th October 2021)
For AEST Zone (GMT +5:30) : From sunrise till 08:56 AM (4th October 2021)
For PDT Zone (GMT -8:30) : From 09:59 AM till 02:56 PM (3rd October 2021) (West Coast of USA)
For EDT Zone (GMT -8:30) : From 12:59 PM till 05:56 PM (3rd October 2021) (East Coast of USA)
Amavasya Gajachchaya Yoga forms on 6th October 2021 and is applicable in continents of Australia, Asia, Africa and Europe.
For New Zealand Time Zone (GMT +7:30) : From 08:40 AM till Sunset
For AEST Zone (GMT +5:30) : From Sunrise till Sunset
For IST Zone (GMT +5:30) : From Sunrise till 04:34 PM
For GST Zone (GMT +5:30) : From Sunrise till 03:04 PM (applicable for UAE, Mauritius etc)
For GMT Zone : From Sunrise till 12:04 PM
Gajachchhaya Yoga is useful when it falls during day time and it has no value when it falls during night time.
So, in 2021 Pitru Tarpan or Shraddh should be performed by people whose father passed away during that time and date.