Regarding witnesses who saw the President react to the first shot. I was looking at Pat Speers website where he has a quite startling list of witnesses who reported Kennedy reacting to the first shot in such a way it indicated he had been hit when compared with his known reaction from the Zapruder footage. He concludes:
"When one performs even a cursory review of the statements regarding the movements within the limousine at the time of the first shot, one finds that 44 of these indicated Kennedy had a reaction to the first shot."
http://www.patspeer.com/chapter5%3Athejigsawpuzzle
However (and I hope I'm not getting this wrong), he seems to be of the opinion that this first shot occurred at z190. At the moment I've not read enough to understand why he's come to this conclusion (if that is indeed his conclusion) but I believe the Z-Film refutes this conclusion. In the first post of this thread there is a partial Z-Film focussing on the SS men in the Presidential follow-up car. It stays with them until z207, almost one full second after z190. At least three agents describe reacting immediately to the first shot (a reaction we can see in Altgens 6) but in the Z-Film posted there is no such reaction. I find it highly unlikely there would be no reaction for almost a full second from any of these trained agents from a shot at z190.
One of the main arguments for a shot before JFK goes behind the Stemmons sign is a quick 'head-snap' from right to left, presumably a reaction to the sound of a shot. However, on closer examination I believe it can be shown no such head-snap occurs.
Look at the hairline of JFK in the following frames:
In the top pic (z207, just before he passes behind Stemmons sign) the parting in his hair on the left side of his head can just be made out. Certainly the way his fringe sweeps up to the parting is clearly visible.
In the second pic (z225, first full frame of JFK emerging from behind Stemmons) his parting is not so visible but the sweep of his hair up to it is.
In the bottom pic (z230, JFK facing straight ahead) the part of his forehead revealed by the sweep of his hairline up to the parting is no longer visible.
Far from turning to his left JFK is still looking to his right as he passes behind the Stemmons sign (z207).
There is no head-snap to the left and, therefore, no reason to suspect JFK is reacting to anything.
Pat Speer assembled a very useful website. Z190 sounds like Jiggle Analysis but I really do not know why he chose Z190. It is best to just read the witness statements. They give the location of the car in relationship to where they were standing when they heard the first shot. Jean Newman states it was just after it had passed her and the Chisms state it was just before them. Mary Woodward states it was when JFK looks forward again which is Z204.
Mary Woodward:
After acknowledging our cheers, he [JFK] faced forward again and suddenly there was a horrible, ear-splitting noise coming from behind us and a little to the right. My first reaction, and also my friends', was that as a joke someone had backfired their car. Apparently, the driver and occupants of the President's car had the same impression, because instead of speeding up, the car came almost to a halt...I don't believe anyone was hit with the first bullet. The President and Mrs. Kennedy turned and looked around, as if they, too, didn't believe the noise was really coming from a gun...Then after a moment's pause, there was another shot and I saw the President start slumping in the car. This was followed rapidly by another shot. Mrs. Kennedy stood up in the car, turned halfway around, then fell on top of her husband’s body…
Ann Donaldson (11-22-63 first person account published in the Washington Evening Star, Second Extra Edition. Note: this article was apparently picked up from a Jackson, Mississippi paper.) "I was standing 70 feet from President Kennedy when he was assassinated today and saw him fall under the bullet that killed him. Mrs. Jacqueline Kennedy threw herself over his body as the President's car speeded up as soon as the driver realized what had happened. The crowd began to scream and wail and people standing nearby began to throw their children on the ground for safety.
I heard two shots. The first shot sounded like a firecracker and the President heard it. He turned to look, as did everyone else, and then the second shot sounded.
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Chisms, Newman, and Secretaries
John Chism : "And just as he got just about in front of me, he turned and waved at the crowd on this side of the street, the right side; at this point I heard what sounded like one shot,"
Jean Newman : "The motorcade had just passed me when I heard that I thought was a firecracker at first, and the President had just passed me, because after he had just passed, there was a loud report"
Gloria Calvery : "The car he was in was almost directly in front of where I was Standing when I heard the first shot."
Karan Hicks : "The car he was in was almost directly in front of where I was standing when I heard the first explosion. I did not immediately recognize this sound as a gunshot"
Karen Westbrook : "The car he was in was almost directly in front of where I was standing when I heard the first explosion. I did not immediately recognize this sound as a gun shot ."
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JBC describes his location in his WC statement:
The only children on the right side of the street was first the Chisms and then the Newmans.
Mr. SPECTER. When you turned to your right. Governor Connally, immediately after you heard the first shot. what did you see on that occasion?
Governor CONNALLY. Nothing of any significance except just people out on the grass slope. I didn't see anything that was out of the ordinary,
just saw men, women, and children.
