Asvini, Varuni, Kirttika. Kirttika is the name of the third daughter of Daksa. It was a custom in Vraja-mandal to name one's daughter after one of the daughters of Daksa Prajapati. So Radharani's mother's name was Kirttika, and Radharani is called Karttiki, in the sense that She is born from Kirttika. So regarding the holy month of Karttika, Sanatana Goswami has given the clue: masanam margasirso 'ham:, Krsna says, "Of all months, the month Marga-sirsa (November-December) represents Me." Karttika precedes Marga-sirsa or Agrahayan. So Karttika month therefore has some reason to be conceived of as representing Radharani. As Krsna represents Marga-sirsa, it can follow that the Goddess representing the preceding month, Karttika, represents Radharani. Karttika month is the month of the vow known as Urjja-vrata. 'Urjjesvari' is also a name of Radharani. Urjjah means 'resources.' All resources culminate in Her. She commands all resources. The sakti, power or resources, are commanded by Her. So the vow followed in the month of Karttika known as Urjja-vrata goes ultimately to the connection of Urjjesvari, Sri Radhika, and thus Vaisnavas lay stress upon the observance of Karttika, especially with the aspiration of satisfying Radharani–to attain Her Service, and the Service of Krsna.

We are also told that in that month the Gopis observed the worship of Katyayani, with the internal aim of satisfying the Devi (Goddess). Nandagopa-sutam devi patim me kurute namah. That was their internal prayer to the Devi Yogamaya: "Please manage in such a way that we can have the Service of the son of Nanda in our own hearty way." With that prayer, the Karttika-vrata was observed by them.

So we also lay some special stress on the observance of the last portion of Chaturmmasya, known as Karttika-vrata. And that is exclusively connected with Service of the Gopis, Radharani, and Krsna; and Srimad-Bhagavatam also comes to encourage us in the line of the Gopis' worship of Katyayani. With that spirit within, we observe the last month of Chaturmmasya more attentively.

(Excerpt from "Holy Talks" from the book "Sri Chaitanya Saraswati Vol I")