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Let me give you a little tutorial in observation and stellar aberration.

The first thing that is factored out in making observations is the rotation of the earth. Observatories are specially built so that their rotation cancels out the earths rotation. You can even buy relatively cheap automated telescopes that do the same thing. The fact that the earth is spinning is of no interest to anyone, it is a bother. It is important to understand the concept but we have bigger fish to fry : )

Now there is another problem, the astronomers would like to know the distance to the objects that they are observing. You measure distance by the difference in the angle that each eye sees an object. If you only had one eye, your depth perception would be terrible.

Astronomers start with two problems, one they typically only have one eye (telescope) and the light from these distant objects is parallel. So even if they had two telescopes it would make no difference. Even if they make an observation in June and another in December the light rays are still parallel and they can’t triangulate the position. They even have this problem observing items in our solar system. Put two observers a thousand miles apart and have them observe the sun at the same instant, their lines to the sun will be parallel.

So now we come to stellar aberration we know that the earth is traveling through space (our solar system is traveling through space) the fact that our solar system is traveling through space distorts the apparent position of the stars in much the same way that that our angular velocity does, except to a much lessor degree. And they would like to eliminate the stellar aberration too. So, some observatory’s automatically compensate for it too.

Essentially the two concepts boil down to the difference between angular velocity and straight velocity, but the effects are identical. That is why I am more than willing to switch back and forth.

Let me give you a little tutorial in observation and stellar aberration.

Thanks!

The first thing that is factored out in making observations is the rotation of the earth. Observatories are specially built so that their rotation cancels out the earths rotation. You can even buy relatively cheap automated telescopes that do the same thing. The fact that the earth is spinning is of no interest to anyone, it is a bother. It is important to understand the concept but we have bigger fish to fry : )

Yes, I know about sidereal. I have a cheapo meade DS90 autostar telescope (90mm/1M refractor) which has goto function and sidereal compensation.

Now there is another problem, the astronomers would like to know the distance to the objects that they are observing. You measure distance by the difference in the angle that each eye sees an object. If you only had one eye, your depth perception would be terrible.

Yes, I know well about the concept of stereo vision and 3D. I've even gone out in the yard and take photos of the area, then stepped over two feet, took another photo, then put them on my computer side by side and looked at them one picture per eye and seen the 3D functionality.

Astronomers start with two problems, one they typically only have one eye (telescope) and the light from these distant objects is parallel. So even if they had two telescopes it would make no difference. Even if they make an observation in June and another in December the light rays are still parallel and they can’t triangulate the position. They even have this problem observing items in our solar system. Put two observers a thousand miles apart and have them observe the sun at the same instant, their lines to the sun will be parallel.

I know all this..

So now we come to stellar aberration we know that the earth is traveling through space (our solar system is traveling through space) the fact that our solar system is traveling through space distorts the apparent position of the stars in much the same way that that our angular velocity does, except to a much lessor degree. And they would like to eliminate the stellar aberration too. So, some observatory’s automatically compensate for it too.

But Stellar Aberration is only 20 arcseconds (which is 0.0056 degrees) and is irrelevant to the distances of the sun or stars!

Essentially the two concepts boil down to the difference between angular velocity and straight velocity,

If you're talking about "Stellar Aberration" and "Light time correction" as the "two concepts" then you're absolutely wrong. Light time correction is irrelevant to transverse velocity, while Stellar Aberration (falling rain experiment) is irrelevant to distance! Furthermore, either one works just fine whether the light source and/or the observer are moving in a straight line or a curved line.

To say that the difference is angular vs. straight velocity is also wrong: For example, it doesn't matter whether the moon is orbiting the earth or just flying by once in a straight line - it will still have light-time correction causing it to appear behind where is, as a function of its own velocity and the distance from it to the observer. On the other hand, Stellar Aberration is irrelevant to the distance or velocity of the light source, but is merely a function of the transverse (cross-ray? :-) velocity of the observer. So really, the difference is that Light-time correction is caused by the velocity of the light source while Stellar Aberration is caused by the velocity of the observer. I'm telling you, since light can continue on in space on its normal course even once its light source has moved does cause there to be a difference between whether the observer is moving or the light source is moving!

but the effects are identical. That is why I am more than willing to switch back and forth.

Only in a very general and non-scientific way are the two effects identical. I mean a plane crash and a shotgut have identical effects too - generally lethal destruction and loss of life. But better gun handling isn't going to prevent plane crashes and better piloting isn't going to prevent shotguns from shooting people. So technically, are the effects of light time correction and stellar aberration identical? No way! First of all, one causes only apparent change in angle (Stellar Abberation.) Light time correction causes the light to actually be coming from a different position of its moving light source (because that's where the light actually came from.). Furthermore, in our discussion of the sun and the earth, Stellar Aberration accounts for at most about 20 arcseconds (or about 0.0056 degrees) while the light-time correction (if the sun were orbiting the earth) would account for 2.1 degrees. Now 2.1 degrees and 0.0056 degrees are simply not the same effect! Furthermore, the two do not even operate on the same principle!

The two are simply not the same thing and we're talking about 2.1 degrees here and it is just dishonest to say you can switch back and forth!

Thanks,

-Jesse