further information.\
The month before [*Shawwāl*]{} is [*Ramaān*]{}, the month of fasting; while one could argue that particular care would be applied to determine the (start and) end of this month correctly (to start and end fasting neither too late nor too early), so that the date of the beginning of [*Shawwāl*]{} was determined more precisely than usual, it could also well be possible that it was considered better to end [*Ramaān*]{} one day too late (than to stop fasting too early), in order not to break a religious law (see also footnotes 4 and 5), so that [*Shawwāl*]{} effectivelly often started one day too late.\
We do not know how Kennedy (1990) obtained AD 775 Sep 1 as date for the end of [*Shawwāl*]{} 158h. Kennedy (1990) gives once [*26 Shawwāl*]{} and once the [*28 Shawwāl*]{}, but he does not comment about the date discrepancy, while Dietrich (1952) gives [*28 Shawwāl*]{}.\
We would like to note that the dating uncertainty as explained above ($\pm 1$ day due to uncertainties in crescent sighting, day counting, or moon phase determination) is often not taken into account when converting a Muslim calendar date to a date in the Julian or Gregorian calendar. 