Velocity correction´ formula for the rotation of the Earth

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SUMMARY

The discussion centers on the velocity correction formula for measuring the Earth's rotation in relation to the Sun's motion. The formula provided is v = 0.464 * sin(H) * cos(D) * cos(L), where 0.464 km/sec represents the Earth's equatorial radial velocity. It is established that neglecting the Sun's rotational contribution, which can reach 2 km/s, leads to inaccurate calculations unless averaging the solar flux across the Sun's entire disc. Additionally, the eccentricity of Earth's orbit introduces radial velocity variations of up to 0.5 km/s over a year.

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  • Understanding of celestial mechanics and orbital dynamics
  • Familiarity with the concepts of radial velocity and its calculation
  • Knowledge of solar physics, particularly solar wind characteristics
  • Proficiency in trigonometric functions as applied in astronomical contexts
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Astronomers, astrophysicists, and students studying celestial mechanics who are interested in accurate measurements of solar and Earth motion interactions.

Ennio
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TL;DR
Does the velocity correction´s formula for rotation of the Earth include Sun contributes?
Let´s suppose we are observing the sun and measuring some spectral lines.

Does the velocity correction´s formula for the Earth include the rotational velocity components of the Sun as well?
or rather
are we basically measuring both velocity contributes of Earth and of Sun together (receeding or approachning depending of course from the angles) ?

v= 0.464 * sin(H) * cos(D) * cos (L) [Km/sec]

0.464 Km/sec is the equatorial radial velocity of Earth
H: hour angle of the Sun [deg]
D: declination of the Sun [deg]
P: Earth latitude of the observatory [deg]

Thanks in advance for your support
 
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Run rotation speed at equator is about 2 km/s while Earth is only 0.46 km/s. Neglecting contribution of Sun` rotation would be a bad calculation, unless you averaging flux across whole disc of Sun. Also, Earth orbit is eccentric, which produce up to 0.5 km/s radial velocities with period of one year.
 
trurle said:
Run rotation speed at equator is about 2 km/s while Earth is only 0.46 km/s. Neglecting contribution of Sun` rotation would be a bad calculation, unless you averaging flux across whole disc of Sun. Also, Earth orbit is eccentric, which produce up to 0.5 km/s radial velocities with period of one year.

Hi @trurle, thank you very much. Do you know how to calculate the solar wind contribution in the line of sight? I have read it is 400Km/sec
 
Ennio said:
Hi @trurle, thank you very much. Do you know how to calculate the solar wind contribution in the line of sight? I have read it is 400Km/sec
Just multiply by cosine between wind direction (outward) and line of sight. 400 km/s is typical for vicinity of Earth indeed.
 

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