Śrīla Bhakti Sundar Govinda Dev-Goswāmī Mahārāj concisely explains the observance of Kārtik in Śrī Chaitanya Sāraswat Maṭh.
Translated from the Bengali editorial published in Śrī Gauḍīya Darśan, Issue 3, Volume 3, 14 October 1957.
Kṛtikā is the name of a nakṣatra (zodiacal sign). There are twenty-seven nakṣatras. The month ‘Kārtik’ comes from Kṛtikā nakṣatra’s name. Śrī Rādhikā’s mother’s name is Kṛtikā. Those who can look up, through fine ontological analysis, towards Śrī Rādhikā’s position far above the nakṣatras have faith that the fundamental identity of the month of Kārtik originates from Śrī Rādhā’s worshippable mother Kṛtikā, see the special presence of Kārtikī Devī, Śrī Rādhikā, within in the month of Kārtik, in that connection, through the Lord’s statement (Bg. 10.35), “Māsānāṁ mārga-śīrṣo ’yam: of months, I am Agrahāyaṇ (the month following Kārtik)”, see Śrī Rādhā-Mādhava’s coupled position, and rejoice.
During this month, all sections of worshippers of Śrī Rādhā-Govinda carefully observe special regulations. Those who have faith in Śrī Gaurasundar’s saṅkīrtan-yajña (sacrifice of chanting the Holy Name) engage in this method of worship in service to Śrī Gaurasundar. Presently, the servitors of Śrī Chaitanya Sāraswat Maṭh engage in saṅkīrtan and various other services. The devotees perform the standard service to the Maṭh’s presiding Deities, Śrī Śrī Guru Gaurāṅga Gāndharvā Govindasundar, and engage themselves daily in various services from daybreak until nearly four and half hours into the night. During the observance of Kārtik, the devotees residing in the Maṭh daily lead a kīrtan through the village at sunrise, and morning, afternoon, and evening recite Śrīmad Bhāgavatam, Śrī Chaitanya-charitāmṛta, and other scriptures, chant the Holy Name, distribute prasādam, and perform other customary devotional practices. Many gentlemen and ladies join in this practice of the eternal dharma and benefit both themselves and their community.