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| frame stack of movie by SAC station Anasco, Puerto Rico |
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| click map to enlarge |
On 15 September 2025, Navigational Warnings appeared that pointed to an upcoming Trident-II D5 SLBM (Submarine Launched Ballistic Missile) unarmed test launch in the Atlantic between 17 and 22 September 2025, from a submarine of either the US Navy or UK Royal Navy positioned some 400 km out of the coast of Florida (update 24 Sept 2025: according to this US DoD bulletin it was an American test launch from an unnamed Ohio-class SSBN (Ballistic Missile submarine). The submarine test-launched four Trident missiles between Sept 17 and 21). I have posted about such tests and the typical pattern of Navigational Warnings associated to them earlier, in an analysis of a Trident launch that was inadvertently captured on camera in a time-lapse by an amateur astronomer on La Palma in September of 2013.
And now we have another case of inadvertant capture on camera of such a launch, and a second opportunity for analysis!
In the evening of 21 September 2025 near 23:30 UTC, eyewitnesses in Puerto Rico saw a fuzzy object and what looked like expanding missile exhaust clouds move through the sky, consistent with a rocket or missile launch. The event was captured by amongst others a meteor camera of the Caribbean Astronomy Society (SAC) near Anasco, Puerto Rico.
Eddie Irizarry of SAC was so kind to send me the video footage for identification and analysis. Immediately, it was clear to me that the video showed the Trident test launch we expected.
In top of this post is a frame-stack from the footage. Below it is a map I prepared showing the northern part of the sky as seen from the camera station in Puerto Rico, with the blue line representing the sky trajectory expected for this Trident launch for an assumed (but see below) apogee altitude of 2200 km. They compare well (note: the video stack shows a part of the trajectory only, up to about azimuth 30 degrees, while the sky map shows the full trajectory).
Here is the video footage itself (courtesy of Eddie Irizarry, used with permission):
The trajectory for this Trident test launch is known, as it can be reconstructed from the Navigational Warnings that have been issued for it. Below is the Navigational Warning, and a map where I have plotted the exclusion zones A-D from it, and a fitted ballistic trajectory:
151958Z SEP 25
HYDROLANT 1538/25(GEN).
ATLANTIC OCEAN.
DNC 01, DNC 16.
1. HAZARDOUS OPERATIONS 171830Z TO 220136Z SEP
IN AREAS BOUND BY:
A. 28-34.00N 076-29.00W, 29-07.00N 076-28.00W,
29-05.00N 075-33.00W, 28-30.00N 075-35.00W.
B. 28-37.00N 075-51.00W, 28-55.00N 075-44.00W,
27-44.00N 070-28.00W, 27-05.00N 070-28.00W.
C. 16-28.00N 044-01.00W, 17-01.00N 043-43.00W,
14-36.00N 038-46.00W, 13-37.00N 039-33.00W.
D. 10-35.00S 001-40.00W, 10-05.00S 001-25.00W,
12-01.00S 002-21.00E, 12-45.00S 002-55.00E,
13-11.00S 002-20.00E, 13-01.00S 002-02.00E,
13-04.00S 002-00.00E, 12-38.00S 001-15.00E.
E. 26-58.00N 070-28.00W, 28-14.00N 070-28.00W,
25-56.00N 063-20.00W, 24-34.00N 063-50.00W.
2. CANCEL THIS MSG 220236Z SEP 25. |
| click map to enlarge |
On the map, I have undicated the part of the trajectory that was captured by the SAC camera on Puerto Rico as a yellow line.
Area A is the launch area where the submarine is located. Areas B, E and C are respectively the splashdown zones of the first, second and third stages of the missile. Area D is the RV (Reentry Vehicle) target zone. The switched designations for the C and E area are probably a clerical error.
The launch area, 400 km out of the Florida coast is one of two well established launch locations for Trident tests in the Atlantic (see my earlier investigation here). Likewise, the target area in the southeastern part of the Atlantic, 900 km east of St Helena at a range of about 9500 km from the launch site, is a well known target location for these test launches.
What cannot be well gleaned from Navigational Warnings alone, is the apogee altitude of this test.
In this post, I will however reconstruct it from a combination of the known missile flight trajectory and measurements of the missile's sky track in the video footage from Puerto Rico, in a similar way as I analysed the earlier 2013 Trident observation from La Palma. For that 2013 test, I found an apogee at ~1800 km.
The video (the original is higher resolution than the version posted in this blogpost) provides plenty of reference stars to do astrometry on the missile path through the sky. So I measured the missile's position with respect to the stars for several frames from the video. Plotting these observed positions (in RA/DEC) on a star map along with the expected sky trajectories in RA/DEC for various assumed apogee altitudes (based on the trajectory from the Navigational Warnings), it is clear that an apogee of 2200 km fits best. Red crosses in the plot below are the measured positions from the video: the blue lines provide the expected missile tracks for various apogee altitudes:
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| click map to enlarge |
(note that I choose to plot RA on the Y-axis rather than X-axis, in order to get a plot orientation that is most easily compared to the video footage).
Earlier, while similarly analyzing the Trident launch seen from La Palma in 2013, I found an indicated apogee of ~1800 km, some 400 km lower than seems to be the case with this latest test launch. Both values are significantly higher than the ~1200 km that is often taken as a canonical value for an intercontinental missile apogee. These tests in the Atlantic therefore appear to be a bit "lofted", perhaps simply to keep the Reentry Vehicle (RV) impact area sufficiently out of the African coast.
From the timing of the Puerto Rico video, the actual launch time was likely somewhere near 23:27 UTC (Sept 21) from a location near 28.8 N, 76.3 W, with a flight time near 41 minutes from launch to RV impact. As seen from Puerto Rico the missile cleared the horizon while at ~150 km altitude, steadily climbing to ~800 km when it left the field of view of the CAS camera station (while continuing its ascend towards apogee). The closest slant range to the camera station was ~1300 km. The big cloud of exhaust gas seen in the early part of the video likely stops upon ejection of the second or third stage. The various smaller "pufs" of exhaust cloud that can be seen later emanating from the fuzzy object, are probably due to either the third stage or post-boost vehicle orienting itself.
(With thanks to Eddie Irizarry/CAS for sending me the footage and for his permission to use it in this blog)
UPDATE 24 Sept 2025:
According to this US DoD bulletin the missile was launched from an unnamed US Ohio-class Ballistic Missile submarine (SSBN). The submarine reportedly test-launched as much as four Trident missiles of the 5DLE variety between Sept 17 and 21. The below image was published, showing a Sept 21 nighttime launch, the missile that was seen from Puerto Rico:
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| Sept 21 2025 Trident missile launch. Photo US Navy/Shelby Thompson |
