Arcturus

Arcturus is a no-twos temperament which tempers out the comma 15625/15309. Having an ~5:3 as a generator, this temperament is the application of the Pythagorean principle of tuning a stack of the next higher prime number and then factoring out powers of the equivalence to tritave composition. However, a heptatonic MOS (2L 5s) will not suffice to produce an understandable rendition of it because a very close ~5:3 generates a L:s ratio between 4:1 and 5:1, which is beginning to get too lopsided to still be a complete presentation of a temperament.

Chords

Arcturus contains the triad 5:7:9 (used in Bohlen-Pierce harmony) and the triad 27:35:45 which divides 5/3 into two nearly-equal parts.

Tuning spectrum

Below is a list of MOS families which present it completely (however smearily) using a generator of 845.3 to 951.0 cents:

Mini chromatic

Anti-chromatic

Template: Scale tree is deprecated. Please use Template: MOS tuning spectrum instead. Details:
Use of a single Comments parameter has become unmaintainable. Existing scale trees should be migrated to the new template, where comments are entered using a step ratio p/q as a parameter:

{{MOS tuning spectrum
| 3/2 = Example comment
| 4/3 = Another example comment
}}

The parameters tuning and depth have been replaced with Scale Signature and Depth, respectively.

Scale tree and tuning spectrum of 11L 2s
Generator^(edo)							Cents		Step ratio		Comments
Generator^(edo)							Bright	Dark	L:s	Hardness	Comments
7\13							646.154	553.846	1:1	1.000	Equalized 11L 2s
						48\89	647.191	552.809	7:6	1.167
					41\76		647.368	552.632	6:5	1.200
						75\139	647.482	552.518	11:9	1.222
				34\63			647.619	552.381	5:4	1.250
						95\176	647.727	552.273	14:11	1.273
					61\113		647.788	552.212	9:7	1.286
						88\163	647.853	552.147	13:10	1.300
			27\50				648.000	552.000	4:3	1.333	Supersoft 11L 2s
						101\187	648.128	551.872	15:11	1.364
					74\137		648.175	551.825	11:8	1.375
						121\224	648.214	551.786	18:13	1.385
				47\87			648.276	551.724	7:5	1.400
						114\211	648.341	551.659	17:12	1.417
					67\124		648.387	551.613	10:7	1.429
						87\161	648.447	551.553	13:9	1.444
		20\37					648.649	551.351	3:2	1.500	Soft 11L 2s
						93\172	648.837	551.163	14:9	1.556
					73\135		648.889	551.111	11:7	1.571
						126\233	648.927	551.073	19:12	1.583
				53\98			648.980	551.020	8:5	1.600
						139\257	649.027	550.973	21:13	1.615
					86\159		649.057	550.943	13:8	1.625
						119\220	649.091	550.909	18:11	1.636
			33\61				649.180	550.820	5:3	1.667	Semisoft 11L 2s
						112\207	649.275	550.725	17:10	1.700
					79\146		649.315	550.685	12:7	1.714
						125\231	649.351	550.649	19:11	1.727
				46\85			649.412	550.588	7:4	1.750
						105\194	649.485	550.515	16:9	1.778
					59\109		649.541	550.459	9:5	1.800
						72\133	649.624	550.376	11:6	1.833
	13\24						650.000	550.000	2:1	2.000	Basic 11L 2s Scales with tunings softer than this are proper
						71\131	650.382	549.618	11:5	2.200
					58\107		650.467	549.533	9:4	2.250
						103\190	650.526	549.474	16:7	2.286
				45\83			650.602	549.398	7:3	2.333
						122\225	650.667	549.333	19:8	2.375
					77\142		650.704	549.296	12:5	2.400
						109\201	650.746	549.254	17:7	2.429
			32\59				650.847	549.153	5:2	2.500	Semihard 11L 2s
						115\212	650.943	549.057	18:7	2.571
					83\153		650.980	549.020	13:5	2.600
						134\247	651.012	548.988	21:8	2.625
				51\94			651.064	548.936	8:3	2.667
						121\223	651.121	548.879	19:7	2.714
					70\129		651.163	548.837	11:4	2.750
						89\164	651.220	548.780	14:5	2.800
		19\35					651.429	548.571	3:1	3.000	Hard 11L 2s
						82\151	651.656	548.344	13:4	3.250
					63\116		651.724	548.276	10:3	3.333
						107\197	651.777	548.223	17:5	3.400
				44\81			651.852	548.148	7:2	3.500
						113\208	651.923	548.077	18:5	3.600
					69\127		651.969	548.031	11:3	3.667
						94\173	652.023	547.977	15:4	3.750
			25\46				652.174	547.826	4:1	4.000	Superhard 11L 2s
						81\149	652.349	547.651	13:3	4.333
					56\103		652.427	547.573	9:2	4.500
						87\160	652.500	547.500	14:3	4.667
				31\57			652.632	547.368	5:1	5.000
						68\125	652.800	547.200	11:2	5.500
					37\68		652.941	547.059	6:1	6.000
						43\79	653.165	546.835	7:1	7.000
6\11							654.545	545.455	1:0	→ ∞	Collapsed 11L 2s

Mini enharmonic

Enharmonic

Anti-enharmonic