What is Turīyasandhyā mentioned in Devi Atharvashirsha?

Question

Yesterday, there was Amrit-Siddhi yoga, also called Bhaumāśvini yoga. Chanting of Devi Atharvashirsha on this day has great significance as mentioned in the text itself: "Bhaumāśvinyāṃ mahādevīsannidhau japtvā mahāmṛtyuṃ tarati". While chanting Devi Atharvashirsha, I noticed the word तुरीयसन्ध्या (Turīyasandhyā) which I think talks about particular timing:

सायमधीयानो दिवसकृतं पापं नाशयति । प्रातरधीयानो रात्रिकृतं पापं नाशयति । सायं प्रातः प्रयुञ्जानोऽपापो भवति । निशीथे तुरीयसंध्यायां जप्त्वा वाक्सिद्धिर्भवति । नूतनायां प्रतिमायां जप्त्वा देवतासांनिध्यं भवति । प्राणप्रतिष्ठायां जप्त्वा प्राणानां प्रतिष्ठा भवति । भौमाश्विन्यां महादेवीसंनिधौ जप्त्वा महामृत्युं तरति स महामृत्युं तरति । य एवं वेद ॥ इत्युपनिषत् ॥ २७॥

Quoting English translation from here:

By Shri Devi’s grace, one escapes from the greatest of difficulties. By chanting this hymn in the evening, one gets rid of the sins committed during the day. By chanting this hymn in the morning, one gets rid of the sins committed during the previous night. By using this hymn in the morning and evening (everyday) one becomes free from all sins. By chanting this during the Turiya Sandhya (midnight when Turiya meets Turiyatita), one gets Vak Siddhi (power of speech). By chanting this hymn, Devata Sannidhya (presence of divinity) is accomplished in a new idol. By chanting this mantra during yoga one escapes from the great death. In this way this Upanishad is the dead of ignorance.

Though the above translation and the Hindi translation of Gitapress (the book I refereed while chanting) says mid-night, I want to know :

• What is the exact timing of Turiyasandhya? (Does it occur at 00:00 clock?)
• Why is it called Turiya?

Answer 1

As mentioned in the answer by Rakesh Joshi it is a secret tradition of the Sri Vidya Upasakas to do a 4th time Sandhya at midnight. This is the time when Turiya meets the Turiyatita.

We can get references for this 4 time Tantrik Sandhya from the article "sandhyA, tritArI and kalpasUtra""

From the perspective of parashurAma kalpasUtra, it is not easy to conclude whether the sUtrakAra intends a single sandhyA as described in shrIkrama or four different sandhyA-s at four times as related to the lalitA, vArAhI, mAta~NgI and parA; and if he does, are these only during the svatantropAsti of the anga vidyA-s (i.e. during the initial panchAngaka purashcharaNa) or even past this stage? rAmeshvara and umAnandanAtha differ here in their opinions. However, various other tantras such as baDabAnala, UrdhvAmnAya, parA, rahasyArNava, paramAnanda etc. as also works such as shrIvidyArNava, saubhAgya ratnAkara, dakShiNAmUrti samhitA, dattAtreya samhitA, saubhAgya lakShmI kalpa etc. clearly prescribe the worship of four sandhyA-s through the recitation of vAgbhava, kAmarAja, shAkta and turIya gAyatrI mantras. This is also the krama followed by most living lineages today.

While I cannot speak for others, the following is the pramANa we follow:

vidyArashmimahAmAlAmantramaNDalasaMyutaH |
vA~nChAkalpalatAyukto chatushcharaNasaMyutaH ||
mahAvidyAsamAyuktaH pAdukAdashakAnvitaH |
chatuHsandhyAsamAyuktaH pa~nchapArAyaNAnvitaH |
pa~nchaShoDhAsamAyuktaH kAdihAdimateShvapi ||

Due to a separate reference to the five ShoDashI-s here, the word mahAvidyA here is traditionally interpreted as pancha samayAs or five mahAvidyAs of kAlikA (dakShiNA, guhyA, kAmakalA, chitAmaNiH and nirvana kAlikA).

Thus, the observance of four sandhyA-s is clearly indicated here.

Note that this is not the Vedic Sandhya Vandanam that is being talked about here, it is Tantric Sandhya. Any disciple who is initiated as per Tantric Paramparas is qualified to perform Tantric Sandhyas.