Canopus

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Canopus
Subgroups 3.5.7
Comma basis 16875/16807
Reduced mapping ⟨1; -5 -4]
ET join b13 & b88
Generators (CWE) ~7/5 = 583.986 ¢
MOS scales 3L 1s <3/1>, 3L 4s <3/1>, 3L 7s <3/1>
Ploidacot beta-tetragem
Minimax error 3.5.7 7-throdd-limit: 1.40 ¢;
3.5.7 49-throdd-limit: 2.80 ¢
Target scale size 3.5.7 7-throdd-limit: 7 notes;
3.5.7 49-throdd-limit: 13 notes

Canopus is the rank two 3.5.7 subgroup temperament tempering out 16875/16807, the amount by which 27/7 exceeds four 7/5s. Having a generator of ~7:5, it possesses non-trivial MOS of the families 1L 2s, 3L 1s, 3L 4s, 3L 7s, and (in most cases) 10L 3s. As 16875/16807 = (540/539)2*(3025/3024), Canopus can be extended to the 3.5.7.11/4 subgroup extremely naturally by tempering out these two commas; prime 53 can additionally be incorporated by means of tempering out 1325/1323, equating (7/5)2 = 49/25 to 53/27.

For technical information see No-twos subgroup temperaments #Canopus.

Interval table

In the below, tritave-reduced harmonics and subharmonics are indicated in bold.

Canopus
# Cents* Approximate Ratios
3.5.7.11/4.53 subgroup
−3 149.9 12/11, 49/45
−2 733.9 55/36, 75/49, 81/53, 84/55
−1 1318.0 15/7
0 0.0 1/1
1 584.0 7/5
2 1168.0 49/25, 53/27, 55/28, 108/55
3 1752.0 11/4, 135/49
4 434.1 9/7
5 1018.1 9/5
6 1602.1 53/21, 63/25
7 284.1 33/28, 53/45
8 868.1 33/20, 81/49
9 1452.1 81/35
10 134.2 27/25, 53/49

* In 3.5.7-targeted DKW tuning

Todo: expand

add tuning spectrum