Which day is the offering?
A Delhi panchang sets four days: Nahay Khay on 13 November, Kharna on 14 November, Sandhya Arghya at dusk on 15 November, and Usha Arghya at dawn on 16 November. Time and Date names Sunday 15 November as Chhath. People stand in the water with fruit and thekua. The fast is the point.
The vow is kept in Bihar, eastern Uttar Pradesh, Jharkhand, Nepal, and wherever those families are. Kartik Purnima is the full moon on 24 November, a different rite. The collection stays empty unless a ghat is already named in the directory.