Crawma
Interval information |
Nuquadso-atrithu comma
(Shannon, [math]\sqrt{nd}[/math])
83521/83486, known as the crawma, is a 19-limit (more precisely, 2.17/13.19/13 subgroup) unnoticeable comma. It forms the difference between a stack of four 17/13's and a stack of one octave and one 19/13.
Temperaments
Tempering out this comma in the 19-limit leads to the rank-7 crawmic temperament, or in the 2.17/13.19/13 subgroup, the rank-2 crawic temperament generated by a tempered 17/13. 31edo's 12\31 = 464.516¢ is the first generator to tune crawic accurately, with 17/13, 19/13, and 19/17 respectively having errors +0.088¢, +1.079¢, and +0.991¢. The CTE generator of crawic temperament, 464.236¢, is extremely well-approximated by 53\137 = 464.234¢.
Terminology
The name crawma was proposed by groundfault as a more distinctive-sounding crow-themed name for the comma than "cawma". The word craw has an archaic sense 'to caw, to croak, to crow'.