Paurṇamāsī was dressed in the reddish garments of an ascetic. She was tall, fair complexioned, and had hair the colour of kāsa flowers. Merely seeing her gave Kṛṣṇa hope.
Here was the goddess known and worshipped in the assembly of perfected saints as Yogamāyā. She was Kṛṣṇa’s internal potency, who makes all arrangements for Kṛṣṇa’s pastimes, and she had appeared in Vṛndāvana as an austere old lady. By the order of her guru, Nārada Muni, she had left her son Sāndīpani Muni in Avantīpura and, out of love for Kṛṣṇa, had moved to Gokula. [This description of Paurṇamāsī is based on Gopāla-campū, Pūrva-campū 2.33 and Śrī Śrī Rādhā-Kṛṣṇa-gaṇoddeśa-dīpikā 1.67–69]
jaya bṛṣabhānu, jaya kīrtidā sundarī
jaya paurṇamāsī, jaya ābhīra-nāgarī
All glories to Rādhā’s divine father and mother, Vṛṣabhānu and the beautiful Kīrtidā. All glories to Paurṇamāsī, the mother of Sāndīpani Muni, grandmother of Madhumaṅgala and Nāndīmukhī, and beloved disciple of Devarṣi Nārada. All glories to the young cowherd maidens of Vraja.
[from Jaya Rādhe Jaya Kṛṣṇa
The Nectarean Glories of Vraja-dhāma]