Sankalpa,according to Hinduism,is Right Determination.
Any act,auspicious or otherwise is to be preceded by Sankalpa.
While Abhivadana Mantra is Geotagging the individual,Sankalpa is Event specific,where the Time of the occasion,location where it is performed is pinpointed.
Year,Season,Month,Thithi(phases of the Moon),Nakshatra(Star),Day,the Gotra,the founder of the Family are mentioned.
I am providing the Sankalpa for Amavasya .
For Grahana suitable changes as in Soorya/Chandra Grahana Punyakaale may be made along with month,day,Thithi,Nakshatra ,Ayana,Year may be made.
I am providing names of seasons and Thithis
Year,month,day,Nakshatra may be found in daily calendar.
Dakshinayana and Uttarayana.
Uttarayan begins from the day of Makar sankranti. Days are longer and nights are shorter during Uttarayan. This period involves pilgrimages and festivals. The period of Uttarayan collides with the Paush Magh month. Uttarayan is known to be the period of Devas. Yagyas, donations, charities, austerities, marriages, mundan etc. are considered to be auspicious during this period.
Dakshinayan begins from 21/22 June. The sun travels from Uttarayan to Dakshinayan on 21st June. According to religious beliefs, Dakshinayan is the night of Kal Devas. Nights and longer and days are shorter during Dakshinayan. During Dakshinayan, Sun travels with an inclination toward the southern direction.
Dakshinayan is the period associated with fasts. Many kinds of auspicious works are prohibited during Dakshinayan. This period is auspicious for Tamsik activities. Dakshinayan is a symbol of lust and desire. Therefore, fasts, yagyas, worship and other religious activities cure diseases and sorrows.
For inauspicious occasions, Lord Vishna as Govinda is invoked,while for auspicious occasions ,Shiva as Parameshwara is invoked by those who worship Shiva and Narayana by those who worship Lord Vishnu.
Sree Parameshwara Prretgyartham,
Sree Narayana Preethyartham.
For Mahalaya paksha,the same format is to followed with changes for month/Thithi/Nakshatra/Year/Season/Ayana(movement of Sun to Tropic of Cancer and Capricorn).
And chant Mahalaya Punyakaale…..Thithi,Vara etc.
nama samvathsare ,utharayane/dakshinayane , rithou(season), mase(month), pakshe(phases of Moon), adhya Amavasyam punya thidhou , …..vasara(day)yukthayam, nakshatra (Star)yukthayam, shubhayoga, shubhaKarana evam guna viseshena, visishtayam asyam Amavasyam punya thidhou, amavasya punyakale, darsa sradham , thilatharpana roopena adhya karishye