Q) If a period began during the day and the following period began during the night – when is veses haflogo observed the following month?
The Shulchan Aruch[1] rules that one cannot be kove’a a veses unless all contributing periods began in the same onah – i.e. day or night. [Day and night in this context begin and end at sunrise and sunset respectively and are not determined by daybreak and nightfall.]
The Pischei Teshuva[2] discusses the relevance of this din to veses haflogo: Should we say, as is implied by the Shulchan Aruch, that unless all periods begin in the same onah – a veses cannot be created. Or, because we are discussing veses haflogo, which is by definition an interval and not a date – do we calculate intervals between periods, and if the intervals between periods are equal a veses haflogo can be created. This latter option would mean that if there is a constant number of onos between periods – a veses can be created – irrespective of whether all periods began in the same onah.
The opinion of the Noda Bi’yehuda (quoted by the Pischei Teshuva ibid) is that unless all periods began in the same onah – there is no concern of veses haflogo.
The conclusion of both Rav Wosner[3] and Rav Ezriel Aurbach[4] is that the halocho is in line with the view of the Noda Bi’yehuda. Rav Wosner adds that if it transpires that a pattern of a fixed number of onos between periods is actually established – this should be considered a veses haflogo (although one does not need to be concerned with this eventuality until a veses kovu’a is actually created – i.e. there is no need to be choshesh for veses she’eino kovu’ah).
[1] יו”ד קפ”ט י”ג
[2] ס”ק ט’
[3] שיעורי שבט הלוי קפ”ט י”ג א’
[4] לבושי עוז (נדה) קפ”ט י”ג
