Valmiki Ramayana Ayodhya Kanda Sarga 15 Shloka 3

विमले bright, सूर्ये Sun, उदिते having arisen, अहनि during day , पुष्ये च when Pushya star, अभ्यागते was ascendent, रामस्य Rama's, जन्म स्थिते constellation at the time of birth, कर्कटकलग्ने ascension of karkataka lagna, प्राप्ते had come, रामस्य Rama's, अभिषेकाय for the consecration, द्विजेन्द्रै: by the best of brahmins, उपकल्पितम् was decided.

The best of brahmins had decided to perform the consecration ceremony after the bright Sun appeared in the sky when the Pushya star approached the karkataka lagna, which was the constellation at the time of Rama's birth.