Hello Nara,
Regarding the supremeness of Gayatri, I can find you references from Sruthi if you regard Sruthi as the final pramana.
Hinduism does not cover people who does not regard sruthi as the final pramana. So it would be like I am talking to a christian/muslim/jain or Buddha or any other religion or an atheist of this world . I do not see a point of discussion then.
Now as per my knowledge I have not find any other upasana methods other than Gayatri referenced as Brahma Vidya in sruthi or smriti. If you have one I would be more than happy to discuss on that. If you are not able to find I think you will have to agree that at least as far as Hinduism or Sanathana Dharma is concerned Gayatri is the supreme Vidya. Now you can find Geetha also called as Brahma Vidya at the end of each chapter but Geeta is not an upasana method it is revealed to arjuna as an experience not an intellectual exercise and only an Arjun (at least one who is or like an Arjuna) is qualified to learn that and any one else trying to learn that will not gain anything from it. It will be like the IIM B Conducting management courses using Geetha it will be helpful only in management and not in the real spiritual path. Adhikara beda is very important as far Hinduism is concerned. Everything is there but it not that everything is for everyone it some of the everything is for everyone. Now if you do not consider sruthi as the final word I think you are free to build up your own religion or subscribe to any other religion than sanathana dharma which exists or even be an atheist. But do not make it hard saying I am a follower of Sanathana Dharma and I do not regard sruthi as the final word. It is like saying "God and evil cannot exist together both at the same time, either you need to be evil or goodness you are free to choose both the ways. Now if you disregard sruthi then sanathana dharma is not for you , Again i am not an authoritative person to declare that as such, but as far as my view is concerned you are out of santhana dharma if anyone does not regard sruthi as the final word. This is not a question of believe or faith, its simple I want to do share trading and I want to learn it then it has its own rules and existing laws are the final authority, now if I do not have a regard for those existing laws fine but I cannot do share trading, each game has its own rules whether I like it or not, or even whether I believe or have faith, and simply since I do not consider those rules I cannot say that it is superstitious because I am not even a player so there is a great lack of real experience. A true rationalist regards experience more valuable than any other method of knoweldge whether it is books, scriptures or any other great Mans word. This is clearly explained in Nyaya Philosophy regarding the pramanas. Now if you want to experience it learn the rules and play and then see if the game works for you otherwise there is no point of lamenting, it is like many people complain I lose the money in Share market, the humble answer is that you did not learn the rules well. now for the people who are follow the rules of Sruthi below is an article about Gayatri.
Vedamata Gayatri
The Gayatri Mantra is called the 'Mother of Vedas' or Vedamata. As such, the initiation of Gayatri is conducted as a ritual called 'Upanayana' or 'Brahmopadesha'. The understanding of the mysteries of Gayatri and its regular practice will lead to the development of a Divine Eye in man. This third eye is called 'Upanayana' since 'Upa' means additional and 'Nayana' means eye. Thus the third eye of knowledge is Upanayana.
In the days of the Vedic Rishis, the ceremony of Upanayana was meant for opening the third eye in the middle of the forehead. It invariably opened a new world, the unseen world of Devas, celestials and Gods. Brahmopadesham means 'Initiation into the knowledge of the supreme Brahman'. Indeed Gayatri is Brahmavidya.
The Gayatri mantra is divisible into two portions:
1. The seven Vyahritis
2. The mantra of Gayatri.
The mantra is of 24 syllables in Sanskrit and composed in a rhythm called Gayatri Chandas. The Gayatri mantra is a cosmic formula. The first seven steps of the Gayatri mantra form the seven Vyahriti-s, which are seven invocations. They invoke the seven layers of the universe, which is composed like a song, with seven musical notes.
1. Bhuh - Physical - Muladhara
2. Bhuvah - Vital - Swadhishtana
3. Svah - Mental - Manipuraka
4. Mahah - Intellectual - Anahata
5. Janah - Super mental - Vishuddhi
6. Tapah - Spiritual - Ajna
7. Satyam - Absolute reality or Parabrahman - Sahasrara
The bottom level or the physical plane is called 'Bhuh' Loka. The plant lives in the vital world with Prana called Bhuvah. Both plants and animals live. The real difference however lies in the difference in consciousness or mental level. This level in the grade of consciousness is what is called a 'Vyahriti' of Gayatri.
The seven Vyahritis are aspects of Brahman who is the Effulgence, the light composed of the seven colors of the solar spectrum. Why is the prayer of Gayatri to be offered at those periods in the day, which is neither darkness nor daylight? A period of the day is called by the ancient Rishis as the 'Hour of Brahman -Brahma muhurtha'. In the early hours of the morning Sandhya, the sky emits a pale bluish light or halo in the east. These Bluish rays coming from the east contain subtle awakening magnetism, which affects the brain. These dawn rays of a bluish hue have also got a soothing effect on the body. Also, the morning air is fully charged with Prana or vital energy. This living electricity is what the body cells require for sustaining good health. This Prana is what the Yogi requires for charging his six Yogic centers during the Sandhya Vandana of Gayatri. This absorption of Prana into the body by regulating its movements by will is called Pranayama. So Pranayama is not just a breathing exercise. What the Yogi calls Prana is not air or breath. It is a process of conscious breathing. It is unfortunate that we have forgotten the science of conscious breathing. However this has been brought back to a few of us by great masters like Babaji, Sananda, Melchizedek and Thoth.
The hour of Brahman is specially selected for Gayatri worship since at that hour, the air is heavily charged with Prana and also the Sun's awakening rays of an electric Blue radiate from the east before the physical Sun emerges form the horizon.
Gayatri is a powerful mantra containing the quintessence of the Vedas, Puranas and all scriptures. There is no Mantra superior to Gayatri. The power, which created the universe, has also created man. This power is reflected on the formula of Gayatri. Gayatri is the mantra embodying the power concealed in this primordial sound called 'Aum' and emanates as universal vibration.
The cosmic sound 'Om' gave rise to the seven Vyahritis of Gayatri, which enable the man, living on the material plane to rise to the spiritual plane of consciousness. Light is associated with Consciousness. In the outer world, the Sun does the same work as the mind does inside us. Both include the process of wakening, so that when the soul is awakened into the consciousness of Brahman, we can see the light of Brahman. Thus, light and Consciousness are inseparable.
The Mantra of Gayatri is a prayer to 'Savita', who is the effulgent sun. 'Devasya' - glowing with immeasurable light - 'Bharga'. The inner SUN of our consciousness is the universal light that dwells in us. This consciousness or Parashakti is called 'Savitr' which also means the deliverer. Her power works on the mind of man and stirs him from his dormant state into conscious awakening.
The Gayatri mantra stimulates us to meditate on the Bhagavati seated in the lotus inside the solar plexus. The lotus symbolizes a yogic chakra in the path of Kundalini, situated along the spinal canal. It is the state of Be-ness. Brahman is the state of 'Sat', which is the truth, which indicates our conscious existence. It enables us to experience our existence as a living reality like our breath. The lotus signifies the symbol of creation, opening petal after petal in the process of evolution.
Also, the allusion to light does not refer to sunlight only, but to the inner light from where the seven vibrations have descended from the 'Brahma-plane' down to earth, and to the living beings. The light vibrations descend as seven planes of consciousness into man. Thus, man is a seven-layered being, corresponding to a structure like the Universe. The seven vibrations of the Sapta Vyahritis are contained within the universal sound 'Om'.
It is clear that what is contained in the macrocosm is also contained in the microcosm. There are seven lokas in man also, which respond to the seven vibrations of Gayatri. These lokas in man are the seven yogic Chakras along the Brahmadanda or the spinal column.
The Gayatri mantra has the enduring potency to grant divine vision and infinite powers. The weak are made strong. The agitated recover peace and calm and the mystery of grace is unraveled through this sacred formula. Manu declares that the Gayatri mantra must be practiced with a balanced mind, near a place of water and that it moulds one's character.
Sage Yagnavalkya says that one must chant Gayatri when stars are visible in the evening and in the morning at sunrise, and that a recitation of Gayatri 1110 times every day will cast off all negative forces. No other form of spiritual activity becomes necessary since this in itself is the most complete spiritual Sadhana. 'Face the east and repeat the Gayatri with Om and the three Vyahritis at least 108 times and destroy all sins', proclaims the Smriti. All karmas will cease to take effect as parched seeds, which do not sprout. The recitation of Gayatri with offerings of parched rice, milk, lotus petals and sesame saturated with ghee, will confer peace and lentitude, splendor and vitality with all desires fulfilled. Offerings made in fire through Gayatri are most effective. 'One who recites Gayatri facing the Sun is liberated of all sins', says Rishi Atri. Perform the mantra with complete faith and love, contemplating on the meaning of the Mantra. This is the best form of Japam. The aspirant's heart becomes pure and he imbibes the power of Parashakti to translate faith into action.
Therefore it is so necessary for all to realize and take to the constant chanting of Gayatri. Whoever surrenders to the Supreme Brahman will surely be rewarded. Brihadaranyaka Upanishad says, 'Worshipper truly becomes pure and he "SEES". The Narada Bhakti Sutra says if one opens his heart to this divine mantra, he will be guided in the right path.
Bhuh stands for the great Brahman who is the basis of life dearer than our breaths. Bhuvah is the name of God as his contact frees the aspirant soul from all unwarranted ills and pains of life arising due to Duality or Dvaita. Svah is the name of the lord, as he pervades the vast universe and sustains all and is All Bliss. Gayatri is a harmony, the most excellent incantation invoked as 'Param Param Jyoti Parame- Oh Thou of lustrous radiance'. At the Sandhya hour of the dawn and sunset, with the inter-play of light and darkness, the Gayatri incantation carries immense splendor, with the spreading rays of the frontal light, which forms the texture of the worlds. Just as the kindling of Agni makes visible a hidden light, so the utterance of the chants makes perceptible a silent principle of sound. The spoken word, the mantra is a revelation of the silence that measures the trance of what is in itself immeasurable. The glory of Gayatri Japa is beyond words. Regular Sadhana leads to liberation from Bondage.
"O man, let us with devotion worship that great Brahman, who is the support of the Sun of all such luminous bodies, who as unprecedented lord of all that was and is all that shall be, existed before creation of the universe and who has created the worlds from the earth to the sun" - Rig Veda X.121.1
"He who practices the Japa of Gayatri regularly for three years assumes the form of air after death and becoming all-pervasive like ether attains the Supreme formless Brahman" - Manu Smriti 11.82
"The learned Brahmana who worships the Sun at the time of rising and setting attains all forms of auspiciousness" - Taittariya Aranyaka P2.A2
Sage Yagnavalkya says: "Bhuh is your Head, Bhuvah is your eye and Svah is your voice". Bhuh is Prana. The brain, intellect and knowledge are all in the realm of the head. They should be ready to serve all those who breathe. Bhuvah means the destroyer of pain. Therefore our eyes must not be indifferent to the pain of others. Svah means the giver of happiness. Therefore our voice should impart happiness to others. Everyone should find truth and hope in our words. This is true worship of Gayatri. This is the simplest way to realize the absolute.
Ultimate reality though beyond empirical knowledge is attainable through intuitive perception. Integration of will is one method of cultivating intuition, which can be achieved by concentrated Gayatri incantation. Intuitive insight is brought about by unified will. Incessant Japa of Gayatri is beneficial. It is the answer to the problems of life.
Gayatri contains the mystic formula about the universe, the solar system viewed as a living thing. It says, you are the living Time or the life span of the universe. You are the divine path. You are the divine power within this universe as well as in the limited body. All creation sprang from this same Parashakti that we call Gayatri. The first thing that the God bestows on man is Splendor -Bhargo, so that one can behold Him face to face. The sun has received only a fraction of that Effulgence. All unworthy pursuits and sentiments of man are kept under control, regulated and transformed by the Bhargo of the Gayatri. Bhargo means the light that leads to progress and annihilates fear and evil. Bhargo has thirty-three divine forces of God that hold on the universe and are also poised in man. These are stated in the Vedas; Eight Vasus or the abodes of the whole creation - Earth, water, fire, air, ether, moon, sun and Purusha. Eleven Rudras are the soul and the ten Pranas namely prana, vyaana etc up to Dhanajaya. The twelve Adityas are the twelve months of the year. Indra is the source of great power while Prajapathi stands for the lordship of creation. The grace of Brahman, which helps us to be virtuous, is known as Bhargah.
The solar globe of the physical Sun is the body of the Solar Logos. Therefore the 'Devaysa' within the Sun is the consciousness pulsating interior to the Sun. what Gayatri signifies is not the visible or the physical Sun, the giver of heat or light, but pure consciousness, symbolized by inner Sun or Savita. The aim of Gayatri is to transform the human nature into divine so as to realize the self as the Parabrahman.
One can comprehend the loftiness of the concept contemplated by the Gayatri Mahamantra by looking into the meaning of the Shlokas of Gayatri Aavaahana during Sandhyavandana. "The single letter 'OM' represents the ultimate reality. Power is its presiding deity. Brahman, the ultimate reality itself is the seer or the Rishi of this Mantra. Its metre or Chandas is Gayatri. It is the personification of the ultimate itself. Its Sadhana is only for the union of the individual self with the ultimate i.e realizing the self as the supreme Paramatman. Let Shree Gayatri the mother of the Vedas, established by Vedas, indestructible, giver of divine blessings, let her come and reveal the Ultimate (Brahma Vidya) to me. Whatever unrighteous deeds are done they are got rid off that day itself. Whatever are done during the night, they are got rid off that night itself.
Oh great power! The embodiment of all letters in the alphabet! The deity that represents the conjugations of Day and night, (the three Sandhyas of the day actually are access points to achieve Bhedana of the three Yogic Granthis in the body!) You are the power of knowledge. You are the enemy of all that is evil. You are the strength and light of the universe and its infinite existence. You are the abode of all Gods. I invoke Gayatri, Savitri the power of Savita, Saraswathi, Lakshmi, Uma or Brahmavidya, and the Rishis. The rishi-chandas-deity of Gayatri are Vishwamitra - Nichrid Gayatri - Savitaa. And of the seven Vyahrities : atri-gauthama-kashyapa-vishwamitra-vasishta-bharadwaja-jamadagni and Gayatri- ushnik-anushthubh-brihati-pankti-trishtub-jagati and Agni-vayu-surya-brihaspati-varuna-indra-vishwedevaah. (Yagnavalkya and Gayatri Tantra forbid the discussion of the fourth Pada of Gayatri since this is to be given only to advanced Sadhakas.)
Agni is her face. Vishnu is her heart. Rudra is her coiffure. Prithvi is her medium of creation. She is alive with the five vital Pranas. She is white in color. She is of 24 letters or eternal Tatvas. Has the three Vedas for three feet. Has six faces in the six directions (Five visible faces for Vamadeva, Sadyojata, and other faces of Sadashiva or the Five Aamnayas, where as the sixth hidden face is the Anuttara Aamnaya which is the abode of the great Vidya of mother Mahatripurasundari). Her purpose is to take us to the ultimate".
yA devI sarvabhUteShu jnAnarUpeNa saMsthitA |
namastasyai namastasyai namastasyai namo namaH ||
the purest form better than todays mineral water 
