[Advaita-l] About Gayatri Japa

[Kripa Shankar]

Namaste,

I have been trying to study as much as possible about the Gayatri mantra but I still feel like my understanding is incomplete. Before doing the japa there is the mudras :‎
‎
Sumukham samputanchaiva vitatatam visritantata‎.......
And it ends with - yeta mudra najaanaati gayatri nishphalam bhavet‎.
‎
Does anyone here know the significance of this mudra? If so, I humbly request you to let me know about the same. 

Regards 
Kripa 
‎
Vyasaya Vishnu roopaya Vyasa roopaya Vishnave ‎
Namo vai Brahma nidhaye Vasishtaya namo namaha