Ramakrishna Paramahamsa    ; 18 February 1836 – 16 August 1886), born Gadadhar Chatterjee or Gadadhar Chattopadhyay (] ), was an Indian mystic and yogi during the 19th-century.
 Ramakrishna was given to spiritual ecstacies from a young age, and was influenced by several religious traditions, including devotion toward the goddess Kali, Tantra, Vaishnava "bhakti", and Advaita Vedanta.
 Reverence and admiration for him amongst Bengali elites led to the formation of the Ramakrishna Mission by his chief disciple Swami Vivekananda.
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 Although he is revered greatly by both Indians & Westerners alike as a true Saint, his devotees look upon him as an incarnation or Avatara of the formless Supreme Brahman as described in the Vedanta.
Kalpataru Day also called Kalpataru Diwas or Kalpataru Utsav is an annual religious festival observed by monks of the Ramakrishna Math monastic order of Hinduism and lay followers of the associated Ramakrishna Mission, as well as the worldwide Vedanta Societies.
 These organizations follow the teachings of Ramakrishna, the 19th century Indian mystic and figure in the Hindu Renaissance.
Nischayananda (May 11, 1865-October 22, 1934) was a direct monastic disciple of Vivekananda.
 He, together with Kalyanananda was responsible for setting up and running the Ramakrishna Mission Sevashrama Kankhal.
 He was inspired by Vivekananda's philosophy of serving man as God and dedicated his life to serve poor and downtrodden in the remote areas where no healthcare facility existed.
 He worked in military service before joining the Ramakrishna Order as a direct monastic disciple of Vivekananda.
 He met Vivekananda in Madras and decided to become his disciple.
 After Vivekananda's death, he went for pilgrimage and by chance came to Haridwar where he met his brother disciple Kalyanananda and joined him in carrying out the works of Ramakrishna Mission Sevashrama Kankhal.
Kalyanananda (1874–1937) was a direct monastic disciple of Vivekananda, who had set up the Ramakrishna Mission Sevashrama at Kankhal, near Haridwar.
 As a monk of the Ramakrishna Order he took up service to the humanity as the most important philosophy in his life and practiced it for the benefit of the local population and the pilgrims.
 He spent thirty six years in Ramakrishna Mission Sevashrama Kankhal to serve the poor and afflicted.
 He was one of the pioneers to set up a hospital in a remote location for the poor, needy and the itinerant monks who did not have access to healthcare.
Sri Sri Ramakrishna Kathamrita (Bengali: শ্রীশ্রীরামকৃষ্ণ-কথামৃত , Śrī-Śrī-Rāmakṛṣṇa-Kathāmṛta , "The Nectar of Sri Ramakrishna's Words") is a Bengali five-volume work by Mahendranath Gupta (1854–1932) which recounts conversations and activities of the 19th century Indian mystic Ramakrishna, and published consecutively in years 1902, 1904, 1908, 1910 and 1932.
 The "Kathamrita" is a regarded as a Bengali classic and revered among the followers as a sacred scripture.
 Its best-known translation into English is entitled "The Gospel of Sri Ramakrishna" (1942).
Ramakrishna Mission Sevashrama is a branch of Ramakrishna Math and Ramakrishna Mission involved in providing humanitarian, healthcare, education and relief services to poor and needy through the universal principle of serving "God in man", based on the motto, "Atmano Moksartham Jagat Hitaya Cha", which was propounded by Swami Vivekananda.
Swami Vivekananda ] , "Shāmi Bibekānondo"; 12 January 1863 – 4 July 1902), born Narendranath Datta (] ), was an Indian Hindu monk, a chief disciple of the 19th-century Indian mystic Ramakrishna.
 He was a key figure in the introduction of the Indian philosophies of Vedanta and Yoga to the Western world and is credited with raising interfaith awareness, bringing Hinduism to the status of a major world religion during the late 19th century.
 He was a major force in the revival of Hinduism in India, and contributed to the concept of nationalism in colonial India.
 Vivekananda founded the Ramakrishna Math and the Ramakrishna Mission.
 He is perhaps best known for his speech which began, "Sisters and brothers of America ...," in which he introduced Hinduism at the Parliament of the World's Religions in Chicago in 1893.
Swami Rudrananda ( 11 March 1901– 30 June 1985) born Muthukrishnan, was an Indian Hindu monk, a disciple of the 19th-century Indian mystic Ramakrishna's direct disciple Swami Shivananda.
Vedanta Society of New York (VSNY) was the first Vedanta Society founded by the Indian Hindu monk, Swami Vivekananda in New York in November 1894.
 In 1897, Swami Abhedananda, another disciple of Ramakrishna, who came to the United States and took charge of the society.
 He was the president of the society until 1921.
 Currently, the Vedanta Society is affiliated with the Ramakrishna Math religious monastic order and the Ramakrishna Mission.
Swami Yogananda (Bengali: স্বামী ষোগানন্দ) was a direct monastic disciple of Ramakrishna, the 19th-century mystic.
 He took his formal initiation from Sarada Devi, the "holy mother" of Ramakrishna Order and spiritual consort of Ramakrishna.
 He was the first vice-president of Ramakrishna Mission.
 He belonged to the family of Sabarna Roy Choudhury, an aristocratic family of erstwhile Bengal.
 He had a short life but he played a very important role during the formative years of Ramakrishna Mission.
 He was also a dedicated and devoted attendant to Sarada Devi during her stay in Calcutta after Ramakrishna's death.
 He was one of the disciples whom Ramakrishna referred to as "Iswarakoti" or the "ever perfect soul".

Question: What is the birthdate of this Indian Hindu monk, a chief disciple of the 19th century Indian mystic Ramakrishna, who propounded Ramakrishna Mission Sevashrama?
Answer: 12 January 1863