Calculation only holds for spherical cows. :D
Under General Relativity what is commonly called gravity is a fictitious force or pseudo force and is purely an artifact of being in a non-inertial frame of reference.
While a very useful in most use cases, and accurate for most needs even Newton was bothered that under his model gravity acts Instanously. This superluminal communication makes the math work but is a spherical cow :)
As a direct comparison under Newtonian mechanics, the centrifugal force is a "inertial" or "fictitious" or "pseudo" force. Due to Einstein's equivalence principle, and under General Relativity gravity is also a "inertial" or "fictitious" or "pseudo" force.
To quote John Wheeler. "Mass tells space-time how to curve, and space-time tells mass how to move."
So if the cow is 5 cows away, you can get something like a get a 4% correction, that perhaps is measurable if you can measure the pull form the cow.
The cow representing Regulus is 4000 cows away, so the correction is less than 1/1000000 and it's safe to take it as a spherical cow.
[Side question: Can LIGO "hear" a nearby cow? It has filters to try to see the chirp of the merge of two black holes, and another filter to only consider the signals that appear in both detectors, so you probably need to train two synchronized dancing cows to fool LIGO. But, do they have enough precision?]
On the LIGO question: Two GPS-synchronized cows, standing near the end-masses, that mooed in the appropriate chirp (correcting amplitude for polarization) would make people nervous enough to do a few calculations and, out of an abundance of caution, put up a fence. I expect the gravitational effect from any mooing (it's a tiny quadrupolar deformation of the cow) to be extremely small.
In practice, even the end-station buildings are large enough to keep cow-moos from happening close-enough to bother the instrument gravitationally. Furthermore, there are no cows at Hanford, and I doubt that there are any near Livingston.
"a system which has spherical symmetry, and whose state is changing because of chemical reactions and diffusion ... cannot result in an organism such as a horse, which is not spherically symmetrical.”
http://www.dna.caltech.edu/courses/cs191/paperscs191/turing....
https://www.spsnational.org/the-sps-observer/fall/2017/consi...