Hi Keri,
Since there are no sources for Ogive's christening date, we assume that it must have been in her birth year 995. She only married Boudewijn IV around 1012, so Hermengarde's birth year was set around 1013, after the birth of her first son Boudewijn V in 1012, when she was approximatively 17 years old.
https://fr.wikipedia.org/wiki/Baudouin_IV_de_Flandre
That Boudewijn IV could have been the 63-year old tather of Judith is almost surely false. Judith's father could very well have been Richard III of Normandy:
https://nl.wikipedia.org/wiki/Judith_van_Vlaanderen
- could be settled after discussion -
Kind regards, CGV
Ogive's date of birth is possibly unknown, he had three children: Baldwin V, count of Flanders MP
Born: August 19, 1012 Bihorel, Seine-Maritime, Normandy, France
Hermengarde van Gent, II MP
Born: around 1013 Flanders, Belgium
Baldwin Barbatus Fair Beard Flanders
Birth: Estimated birth between 1000 and 1036
Death: May 30, 1036
As we see the date of birth of Ogive would be unknown as well as that of Baldwin Barbatus.
We also have at least 3 site that put her birth year in 985 or 986.
https://nl.m.wikipedia.org/wiki/Otgiva_van_Luxemburg
https://www.genealogieonline.nl/en/stamboom-van-osch/I32545.php
https://www.janmolenweg.nl/g/111924.html