What does the photograph taken in Stockholm's inlet on 31 October really show? A submarine? Or something completely different? "It was not a submarine. We are completely sure of that. And we are still equally sure it was a submarine that violated Swedish territory a few weeks earlier," says Ola Truedsson, Commander Maritime Component Command of the Swedish Armed Forces.
"Only after extensive and time-consuming analytical work is it possible to assess observations, and it is only the Armed Forces that can substantiate the level of truth in the observations. The precautionary principle applies from the Armed Forces' side when drawing rapid or definitive conclusions on what are presented as observations in the media," says Ola Truedsson.
One of the many autumn observations was made on 31 October, and was given a lot of attention in the mass media. The Armed Forces do not usually comment on single alleged observations or speculations, but in this particular case the Supreme Commander decided to make an exception.
"We are doing this to clarify what was perceived to be a submarine in a photograph, but what we now know with certainty was a civilian working ship. What we are now making public is one of several parts in our analysis of the observations. The reason that we do not demonstrate all the analytical methods and capabilities is because we do not want to disclose them, but the analysis method described is fully sufficient. We are absolutely sure of our conclusion," says Ola Truedsson.
The conclusion is substantiated by four photographs published in a separate document (in Swedish).
Figure 1 is a reference image taken at exactly the same location as the photograph taken on 31 October. There are yellow reference lines in the image drawn between several known fixed points in the terrain, such as the lighthouses at Elfviksgrund, Granholmen and Stora Höggarnsbank, which are also inserted in the image. The green starboard buoy at Elfvik is also inserted as a point.
Figure 2 is the photograph taken on 31 October. In the photograph there is an unidentified object which appears to be moving at speed through the water. The object is circled with a blue line. There is another ship, identified by the Armed Forces, circled with a green line. The same yellow reference lines as in Figure 1 are also inserted in Figure 2. Through metadata in the photograph, it is known that it was taken on 31 October at 14.29:09 UTC.
Figure 3 shows an excerpt from a sea chart of the relevant area, with the same yellow reference lines inserted. There is also a purple rectangle, which is the possible area in which the unidentified object in Figure 2 could be located. The purple rectangle has been calculated with the help of the yellow reference lines. The purple rectangle is approximately 700 metres long and 100 metres wide.
Figure 4 shows a digital sea chart of the same area as in Figure 3. It includes AIS trails from three vessels that were moving in the area during the time period in question. AIS is a transponder that makes it possible to identify a ship and follow its movements from other vessels and from land. The purple rectangle is also inserted on the digital sea chart, as well as the three trails with timestamps: the green track (the ship is now on same return route as compared with earlier in the day), the red track and finally the blue track that shows the civilian working ship's route. The blue track corresponds to the blue circle shown in Figure 2. From the AIS information it can therefore be seen that when the photograph in Figure 2 was taken, the AIS transponder from the civilian working boat was in the area of the purple rectangle.
There was no other AIS transponder in the purple rectangle when the photograph in Figure 2 was taken.
No other unidentified objects can be seen in Figure 2 when AIS tracking takes place in the area.
The human eye is nevertheless a very good sensor, and the Armed Forces encourage the public to continue contacting the authority regarding observations in the archipelago and at sea.
"We evaluate every observation received separately and process them, as well as personal contact, in accordance with a very precise procedure designed by the secret services. Everybody who observes something and reports it can be assured that we take into account the individual's personal integrity and we do not disclose their personal information," says Ola Truedsson.