On snāna-yātrā day a very festive mahābhiṣeka of Śrī Jagannātha, Baladeva and Subhadrā-devī is performed according to rules and regulations. Brahmā and all the other demigods participate in this ceremony without being seen. Afterwards, the curtain of the Jagannātha temple is closed and there is no darśana for fifteen days, because Śrī Jagannātha becomes sick from bathing too much. This period is called anavasara, and Lakṣmījī serves Him alone at that time. During that period, Śrī Caitanya Mahāprabhu, the embodiment of vipralambha-rasa, used to go to Ālālanātha, because He was so restless in separation from Jagannātha. After anavasara, on the second day of śukla-pakṣa, the waxing moon, from the day after the dark moon till the full moon, Śrī Jagannātha, Baladeva and Subhadrā ascend three different chariots and start their journey for Sundarācala (Guṇḍicā). But Śrī Jagannātha-deva does not tell His wife Lakṣmījī that He is going to Vṛndāvana. After sporting for nine days in Vṛndāvana (Sundarācala), He returns to Śrī Mandira in Nīlācala. Going to Sundarācala is called ratha-yātrā, the day they come back from there is called the return yātrā, and the fifth day from the beginning of the ratha-yātrā, and the fifth day from the beginning of the ratha-yātrā is called herā-pañcamī.
Excerpt From: Śrī Śrīmad Bhaktivedānta Nārāyaṇa Gosvāmī Mahārāja. “Ācārya Kesari Śrī Śrīmad Bhakti Prajñāna Keśava Gosvāmī.”