Is the fast of one who drank during the Fajrathan by mistake, and stopped drinking before the pronouncement of "Ashhaduanna MuhammadanRasulullah," valid?

If the questioner drank believing that the Adhan had not yet begun, but then it became clear to her that she drank after it had started, then if the muezzin was calling the Adhan after the true dawn became apparent, she is subject to the ruling of one who drank believing the night remained, and then it became clear otherwise. There is a difference of opinion among scholars regarding the validity of the fast in this case. Some scholars hold that the fast is invalid and requires qada' (making up the day) along with refraining from eating and drinking for the rest of the day, while others hold that the fast is not invalid and does not require qada'.

However, if the muezzin calls the Adhan based solely on a calendar, some scholars permit leniency for eating or drinking for about a minute or so after the Adhan. This issue is not related to a fasting person drinking forgetfully.