The old solsticial rite of the Indo-Aryans is performed on the second last-last day of the year (mahAvrata). The description of the oldest version of the rite is seen in the pa~nchavimsha, aitareya and shA~NkhAyana brAhmaNa. The clearest explanations of the ritual actions are found in the shA~NkhAyana shruti. It appears to preserve some of the archaisms of the Proto-Indoeuropean form of the rite. It was literally round the clock and one requires considerable energy to perform it successfully.
1) It begins in the morning with a bahiShpavamAna soma rite. The hotar chants the Ajya (the chants composed by the kANva with one R^ik for every month of the year:12 ; then the chants composed by vasiShTha with one R^ik to agni for every moon cycle in the year + 1 R^ik (head of prajapati) for the remaining days that add up to the solar year: 24+1=25 ) and prayoga shastras (chants to indra, vAyu, mitra, varuNa, ashvins and sarasvati) and the prashAsta, brAhmaNachChamsin, potar, neShTar, agnIdhra and achChAvAka (the hotraka priests) chants the 3 Ajya shAstras.
2) In the midday pouring the mAdhyandinapavamAna and the pR^iSTha pavamAna stotras and the marutvatIya (the nivids are recited in ekashruti between the vasukra aindra chants in this shAstra) and niShkevalya shastras (respectively to indra with maruts and indra) are chanted
3) In the evening the soma pouring is made with the ArbhavapavamAna stotra, yaGYnAyaGYnIya sAman and the vaishvadeva and AgnimAruta shastras.
5) Then the performers rest for the night session as the sacrificial place is swept and the various accessories are brought and set up.
-A swing of udumbara fig wood is made for the hotar to sit on.
-A seat for the udgAtar with a darbha grass cushion is made.
-The adhvaryu stands on cushion of kusha grass while chanting the yajuses.
-The brahmA and other priests get reed mats.
-A vANa with 100 strings, with the body made of udumbara and handle of palAsha woods, covered with a brown ox hide is readied for the udgAtar to accompany the sAma gAnaM. A reed bow decorated with leaves is used to play it.
-Following musical instruments to accompany the sAma ganaMs: avaghaTarikA (a pot instrument), alAbuvINA (a vINA), ghATakarkari (the pot-cymbals?), godhAvINAKA (vINA), kANDavINA (vINA) and picchorA (flute) are readied.
-6 mR^idanga drums are placed all around the saman singers
-behind the AgnIdhra altar a hole is dug up in a hemispherical form and covered with the hide of a sacrificed bull. This is the earth drum that is played to accompany the sAma gAnaM.
-a round piece of hide, held up by two posts is set up as an archery target to the left of the AgnIdhra fire.
-a chariot with a single horse with a bow and 3 arrows are readied for the kShatriya to use.
-pots filled with water are readied for the dancing maidens
6) At night the prAtaranuvAka chant comprising of 1000 R^iks to indra from the R^ig and atharvan is chanted by the priests. Then an animal or a flour model of an animal is offered to indra and agni. The sacrificial implements are then washed carefully outside the sacrificial area and brought to the sacrificial hall, the sadas, where the guests and witnesses are seated.
7) Then the mAhendra cups are filled and soma offerings made with the yajur vedic mantras to indra.
8) Then the adhvaryu goes before the hotar’s fire altar. The hotar utters the praiSha “adhvaryu, now stop”. The hotar then leaves the sadas and goes around the AgnIdhra’s altar and bending his right knee, takes with a sruk made of udumbara wood, and makes 8 offerings of ghee to the devas. He then puts down the sruk and stands in front of the sadas, north of the shruti altars, and faces east and in a low tone chants the parimAd formulae.
-The udgAtar sings the A~ngirasa, bhuteChad, krosha, anukrosha, payas, arka and arkapuShpa sAmans, with hotar in a low tone muttering the parimAds.
-He then invokes savitA in the sacrificial hut and returns to the sadas and holds the swing from behind. He then instructs the adhvaryu as to how to proceed and the prastotar regarding the stotriyas.
9) The adhvaryu then initiates the mahAvrata sAman. The udgAtar mounts his udumbara stool and the other brAhmaNas sit on their mats. The udgAtar picks up the 100-stringed vANa and begins playing it, singing the mahAvrata sAman. The wives start playing on the other instruments that were brought in, while the drummers start beating the mR^idangas and the earth drum. Maidens water pitchers on their heads dance thrice to the left round the mArjAlIya altar singing the madhu gAnaM. Then they dance thrice to the right in silence. The horse is then yoked to the chariot and the kshatriya mounts it and taking the bow and three arrows encircles the vedi and shoots the target even as he is riding (these are stick to the target marking the 3 stars of Orion).
10) The prastotar signals to the hotar with the formula ‘A velA’. The hotar then pulls the swing towards him and performs prANAyAMa thrice and chants some gAthas. He then holds the swing stretches his feet forward and performs prANAyAMa once. He then sits on the swing and with his right hand touches the back of the swing and chants the prathama pratihAra and concludes with a prANAyAMa. The end of the chant all the drums stop beating and the maidens put down their jars on the mArjAlIYa.
-The prastotar then utters the formula ‘eShA’. The hotar then begins chanting the niShkevalya shAstra to indra.
-The chants corresponding to different set of bones of the body are chanted
-The 9 sets of 80 R^iks to different devas corresponding to the 720 days and nights of the normalized year are chanted.
-Then he chants a 100 triShTub R^iks to indra, followed by the hirANyastUpa chant and the yAtaUtIya chant. Then the procession of the nakshatras in the sky is enacted by the combination of the sajanIya chant (RV2.12) and RV2.14 which together constitute 27 verses, one for each nakshatra. The adhvaryu chants the nakshatra hymn for the 27 nakshatras. This is followed by the sUkta of of vishvAmitra begining with A yAhy arvA~N…
-finally the udubrahmIya hymn with viharaNa chandasaM permutation is chanted.