Sirius tuning fork — 173.76 Hz

173.76 Hz is the tone of Sirius, the brightest star in our night sky. It is not part of Cousto's canonical set: it extends the method to an object beyond the Solar System.

Sirius A and its white dwarf, Sirius B (the small dot at lower left). Their mutual orbit gives the frequency · NASA, ESA, H. Bond (STScI), M. Barstow

Frequency (middle octave)	173.76 Hz
Note	F · −8 cents from standard tuning A = 440 Hz
Tuning in which this is an exact note	A = 437.85 Hz
Cycle	mutual orbit of the binary star Sirius A and Sirius B50.13 years
Doublings from the cycle's frequency	38
Color (the same frequency as light)	violet · 392 nm
Paint on the Acutonics tuning fork	none: Acutonics has no such fork
What can be checked	Reproducible

The period used here is an unusual one. It is not an orbit around the Sun, which a star does not have, but the mutual orbit of a binary system: Sirius A and its white dwarf companion, Sirius B, circle their common center of mass every 50.13 years. This is a measured value, refined with observations from the Hubble telescope.

The published figure is usually rounded to 173.8 Hz, and to the ear the difference is irrelevant. But octaves are better built from the exact value: in pitch the rounding error is the same in every octave, but in hertz it doubles with each one, and for the fork of the fortieth octave, 695 Hz, it already reaches 0.16 Hz — when tuning by beats, that is one beat roughly every six seconds.

Sirius has a technical quirk, which is why we check its color separately: it lies 0.12 Hz above the point where the color calculation “flips over”. Naive rounding sends it into the infrared, which the eye cannot see; with the correction it comes out violet, the color the guides describe.

How this number is obtained

The axis is logarithmic: each doubling raises the sound by exactly one octave. The pitch goes up, the note stays the same.

Given: the period of the binary star Sirius

50.13 years = 1 581 931 996 seconds

1The frequency of the cycle itself: how many times it repeats per second

1 ÷ 1 581 931 996 = 0.000 000 000 632 14the same in short form: 6.32 × 10⁻¹⁰ Hz

A tiny number that cannot be heard: human hearing starts at about 20 Hz. But it is a real frequency, and we can keep working with it.

2Raising it into the audible range: each doubling is one octave up

0.000 000 000 632 14 × 2 = 0.000 000 001 264 31st doubling

0.000 000 001 264 3 × 2 = 0.000 000 002 528 62nd doubling

0.000 000 002 528 6 × 2 = 0.000 000 005 057 13rd doubling

⋮34 more doublings just like these

86.88 × 2 = 173.7638th doubling: now it is in the middle fork band

Or, in a single line:

0.000 000 000 632 14 × 2³⁸ = 173.76 Hz

where 2³⁸ = 274 877 906 944, the number of times the frequency has grown

The value Cousto published is 173.76 Hz. It matches.

3Which note it is

12 × log₂(173.76 ÷ 440) = −16.08semitones from A

nearest whole number: −16 = Fand that is the note

remainder: −0.08 of a semitone = −8 centshow far the tone is from the note

One hundred cents make one semitone. Planetary frequencies almost never land exactly on a note: orbits know nothing about musical tuning.

4In which tuning it would be an exact note

173.76 ÷ 2^(−16 ÷ 12) = 437.85 Hz

An ordinary piano is tuned to A = 440 Hz. Here the tone gets a tuning of its own, and for the Om tone it is exactly the much-discussed 432 Hz.

5Color: the same frequency raised all the way to light

173.76 × 2⁴² = 764 208 463 318 105 Hzthat is 7.64 × 10¹⁴ Hz, already visible light

299 792 458 ÷ 764 208 463 318 105 = 392 nmwavelength → violet

Divide the speed of light by the frequency and you get the wavelength. This is a model, not the measured color of a planet, but the arithmetic is exactly the same as for sound.

Octave ladder

Octave	Frequency	How it is used
2^35	21.72 Hz	below or at the edge of hearing
2^36	43.44 Hz	below or at the edge of hearing
2^37	86.88 Hz	low: stronger vibration on the body
2^38	173.76 Hz	the main tuning fork
2^39	347.52 Hz	high: work in the field above the body
2^40	695.04 Hz	high: work in the field above the body

Two values, and both are “official”

published value: 173.76 Hz, the exact calculation (period of 50.1284 years (Bond, 2017, Hubble observations)) and 173.8 Hz, rounded (manufacturers' practice).

A difference of four hundredths of a hertz cannot be heard, but octaves are better built from the exact value: in hertz the error doubles with every octave, and at the fortieth, for the 695 Hz fork, the rounding already shifts the tone by 0.16 Hz.

What tradition ascribes

Tradition

Expansion of consciousness, the “star” theme. Outside Cousto's canon.

This is a system of correspondences, not the result of a measurement: controlled studies of planetary frequencies do not exist. We present the tradition because it exists and the practice is built on it — but we call it tradition.

All frequencies in one chart · how the calculation works · what has been proven