I have had enough of your so called enlightenment. As usual, you interpret things the way you want to. My interpretation of what Gibson said is pretty straight forward. BI 7597 makes it pretty clear what he saw once he got the glasses on them.
7596. Could you see when you saw this flash at all how far away you thought it was? - It was right on the horizon.
7597. What sort of a light was it? You called it a rocket? Was it a flash; did you see it go up into the sky? - Yes.
7598. What colour was it? - White.
And guess what? About 20 minutes later, according to what Stone tells Stewart, Stone thinks he see's a light to the southward.
8886. Did you ask him whether he had seen anything else? - [Stewart] He [Stone] said he thought there was a light to southward about 20 minutes to 4.
Which by around 4 o'clock becomes two masthead lights that Stewart picked up and pointed them out to Stone who acted like he saw that vessel for the very first time. Now what vessel could that be to the southward at that time and little abaft the beam? Oh, must that not be mystery vessel Y, the one that fired rockets right on the horizon a little distance apart in the SSW around 3:20?
Now, now, Sam, keep your hair on.

Let's keep this discussion in perspective.
First of all, my interpretation of marine phenomenon and the actions of sailormen is not "so-called" it is more likely to be factual since I am the one who has actually seen and been involved with such things on many occasions.
Consequently, the word "Interpretation" should not be confused with the expression "educated guess".
There is very little "pretty clear" about Gibson's evidence relative to the last hour of his Watch.
For instance: how can a rocket be "right on the horizon" and go "right up in the air"? That is a contradiction in terms. In fact, your bold emphasis also contradicts your own argument.
The word "rocket" in that exchange is used by the questioner and the witness but the description of what was seen was a "flash".
No doubt the following will be dismissed out of hand, but one must try.
The first
flash in the firing sequence of a signal is on the deck. Then there is a second
flash at maximum trajectory... thereafter, and for some time, the signal gives off a steady light from multiple - closely concentrated sources. Gibson described seeing a flash which he called a rocket. You like his evidence during this part of his interrogation, so consider the following:
In their reports to Lord on April 18, Gibson wrote:
"At about 3:20 looking over the weather cloth, I observed a rocket about two points before the beam (Port), which I reported to the Second Officer. About three minutes later I saw another rocket right abeam which was followed later by another one about two points before the beam." Whereas Stone wrote
:
" We saw nothing further until about 3:20 when we thought we observed two faint lights in the sky about S.S.W. and a little distance apart." Stone saw
lights in the sky at 20 minutes to 4,
not a ship's masthead lights. Gibson referred to them as "rockets" and "flashes".
However, Gibson also said:
"7574. What was it? A: - About 3. 40 the Second Officer whistled down to the Captain again. 7
575. Twenty minutes to four? A: - Yes.
7576. Did you see him doing it? A: - Yes.
7577. Did you hear what he said? A: - No.
7578. Did anything happen after that? A: - Yes.
7579. What? A: - I saw three more rockets, Sir. So if I am reading this correctly, Gibson saw three flashes at 3- 20 am and 40 minutes later, at 4-40 am he saw 3 rockets. Don't speculate, Sam -then select the evidence you like - consider all of it.
Gibson's recollections do not make sense.
For a ship with and air-shape such as the C to swing 4 points...45 degrees...22.5 degrees to port then back another 22.5 degrees in 3 minutes seems a bit far fetched to say the least.
A stopped ship tends to lie athwart the wind, The point of influence of wind moves depending on the profile of the ship presented to the wind. On a ship with midship accommodation, the PI will be fairly close to the CG i.e. at the mid-length point. All which means that C would not have been swinging back and forth at such a rate. (Of course you know that).
What you are unable to deny is the fact that both men used the expression
"right on the horizon" and I have previously pointed out to you the true meaning of that expression when taking into consideration the presence of abnormal refraction. A fact which once again, you ignored.
Apart from the foregoing- am I correct in suggesting that you have already argued with another member that the vessel lights seen at 4 am were probably those of the
Mount Temple?