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Flattop Fiesta

@flattopfiesta.bsky.social
359 followers 27 following 731 posts

I like to find ships in ESA Sentinel satellite pictures

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Flattop Fiesta @flattopfiesta.bsky.social · 13h
Looks like the Liaoning is out to sea, last spotted at the pier at the Yuchi base near Qingdao on the 10th
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Flattop Fiesta @flattopfiesta.bsky.social · 11/10/2026
[if this were something happening today I'd go pretty overboard with the annotation but we'll leave it as is]
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Flattop Fiesta @flattopfiesta.bsky.social · 11/10/2026
Seeing the Vikrant the other day reminded me of this image from around this time last year, where it conducted joint exercises with the UK carrier group. I had not yet taken up my shipwatching hobby then so I wondered if it was covered in any satellite imagery. Turns out it was very well-captured!
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Flattop Fiesta @flattopfiesta.bsky.social · 11/10/2026
[I have a hunch this Sentinel-3 blob might be the Vikrant but no way to tell for sure.]
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Flattop Fiesta @flattopfiesta.bsky.social · 11/10/2026
The ship also visible in yesterday's USGS Landsat images as well, timestamped about ten minutes earlier.
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Flattop Fiesta @flattopfiesta.bsky.social · 10/10/2026
Realizing another application for Sentinel-3 data is "filling in" a scene when a ship appears near the edge of an imaging stripe. These two composited satellite passes are timestamped 20 minutes apart.
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Flattop Fiesta @flattopfiesta.bsky.social · 10/10/2026
Another view of HMS Queen Elizabeth in Belfast in today's Sentinel-2 optical imaging.
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Flattop Fiesta @flattopfiesta.bsky.social · 10/10/2026
Aircraft carrier USS George H.W. Bush visible at the edge of the imaging stripe in yesterday's Landsat images, departing Phuket, Thailand.
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Flattop Fiesta @flattopfiesta.bsky.social · 10/10/2026
Indian Navy aircraft carrier Vikrant visible off the coast of Goa in today's Sentinel-2 satellite images.
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Flattop Fiesta @flattopfiesta.bsky.social · 10/10/2026
Expanded view with better L2A color processing, showing the USS Abraham Lincoln as well as its sister ship the USS Carl Vinson nearby.
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Flattop Fiesta @flattopfiesta.bsky.social · 10/10/2026
USS Ronald Reagan visible in today's Sentinel-2 imaging as well, underway off the Baja. [They've had their AIS radio off but I just had a feeling about this helicopter...]
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Flattop Fiesta @flattopfiesta.bsky.social · 10/10/2026
USS Abraham Lincoln back at its home port in San Diego following record deployment, visible in today's Sentinel-2 satellite imagery.
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Flattop Fiesta @flattopfiesta.bsky.social · 10/10/2026
USS Makin Island and accompanying amphibious ship USS John P. Murtha visible at the pier in Pearl Harbor in today's Sentinel-2 satellite images.
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Flattop Fiesta @flattopfiesta.bsky.social · 09/10/2026
HMS Queen Elizabeth on port call in Belfast in today's Sentinel-1 synthetic aperture radar images.
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Flattop Fiesta @flattopfiesta.bsky.social · 09/10/2026
I have thought about writing a little script that will optimize this from my "coarse" placement but that is probably a little excessive.
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Flattop Fiesta @flattopfiesta.bsky.social · 09/10/2026
It is possible (but less likely) that the ship would be contained to just one pixel. More likely than not it spans multiple pixels. Since the AIS gives me a heading to orient the ship I place it so that its area is more or less divided proportionately to the luminance of the pixels that contain it.
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Flattop Fiesta @flattopfiesta.bsky.social · 09/10/2026
To explain a little: if we go to the GPS position of the AIS Ping from the same minute the satellite went over we see it is very proximate to a patch of four "bright" pixels in line with the ship's heading. Unless that's a tiny cloud in the exact same spot that is the ship.
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Flattop Fiesta @flattopfiesta.bsky.social · 09/10/2026
USS Ronald Reagan continuing exercises near San Diego apparent in today's Sentinel-3 pass. Think I have settled on an aesthetically pleasing way to indicate a ship's position in low-resolution imaging by just putting a drop shadow around a negative space.
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Flattop Fiesta @flattopfiesta.bsky.social · 08/10/2026
[Alternative composition grouping related annotations a little better]
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Flattop Fiesta @flattopfiesta.bsky.social · 08/10/2026
Amphibious carrier USS Makin Island and amphibious landing platform ship USS John P. Murtha visible in today's Sentinel-1 radar images approaching Pearl Harbor.
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Flattop Fiesta @flattopfiesta.bsky.social · 08/10/2026
USS Abraham Lincoln returns to San Diego following its deployment, visible in the descending pass of today's Sentinel-1 synthetic aperture radar imaging. [I like the way the compositing turned out on this one]
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Flattop Fiesta @flattopfiesta.bsky.social · 08/10/2026
Yesterday's Sentinel-1 synthetic aperture radar images also captured this scene. [The carrier is quite unambiguous but as is often the case with smaller vessels I've shown a "best guess" fit with the thought that the major point of contrast is the spot where helicopter hangar meets the deck. ]
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Flattop Fiesta @flattopfiesta.bsky.social · 08/10/2026
Nice clear view of the USS Abraham Lincoln and USS Ronald Reagan operating near San Diego in today's Sentinel-1 radar images. The Lincoln should be returning to port today or tomorrow.
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Flattop Fiesta @flattopfiesta.bsky.social · 07/10/2026
Aircraft carrier USS Nimitz underway east of Norfolk in today's Sentinel-3 images, identified via AIS cross-reference. [Working out the details but I think the "keep it simple" dashed outline over the Sentinel-3 pixels might be the way to go with this format]
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Flattop Fiesta @flattopfiesta.bsky.social · 07/10/2026
The ship holding still at a position distant from a landmass makes for a nice illustration of my recent experiments with Sentinel-3 data. Overlaying images from the two satellites, one can see the entire ship is about the size of a single pixel, and dumb luck has placed it neatly within one.
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Flattop Fiesta @flattopfiesta.bsky.social · 07/10/2026
Some contrast stretching and expanded annotation of this scene, showing the USS George H.W. Bush along with a nearby destroyer escort at anchor near Phuket, Thailand.
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Flattop Fiesta @flattopfiesta.bsky.social · 07/10/2026
D'awrr shucks. xD Thanks!
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Flattop Fiesta @flattopfiesta.bsky.social · 07/10/2026
[[this little aside on SAR visualization was meant to reply to this one]] bsky.app/profile/benj...
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Flattop Fiesta @flattopfiesta.bsky.social · 07/10/2026
Oh I see now this comment wasn't threaded with your other one about the islands in SAR data😅 Yeah I suspect my empirically-chosen channels are similar to various "urban area" bands. The trouble is the Sentinel-3 data is just so limited that achieving contrast still just gives you those four pixels.
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Flattop Fiesta @flattopfiesta.bsky.social · 07/10/2026
The QE carriers also usually have a bright spot for the ski-jump, since it's only half the width of the bow and makes a sharp 90° join that shows up well. The full-width ski-jump on the Chinese and Indian carriers by contrast acts like a parabolic dish and makes the whole front of the ship dark.
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Flattop Fiesta @flattopfiesta.bsky.social · 07/10/2026
But the dark middle of the deck is actually a pretty clear characteristic of a carrier by itself -- commercial ships are usually bright the whole way through. Plus the "box" superstructure on one end often makes these X-shaped backscatter patterns
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Flattop Fiesta @flattopfiesta.bsky.social · 07/10/2026
Yeah! The island is generally the biggest point of contrast on most carriers, so the QE ships having two makes them easier to spot in SAR images. For this reason the SAR urban script does in fact do a good job of visualizing carriers, but the middle of the deck is actually usually pretty dark.
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Flattop Fiesta @flattopfiesta.bsky.social · 07/10/2026
HMS Queen Elizabeth visible in today's Sentinel-1 synthetic aperture radar images, heading into Belfast.
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Flattop Fiesta @flattopfiesta.bsky.social · 07/10/2026
Japanese light carrier Kaga visible in today's Sentinel-2 satellite images, parked near the dry dock at Kure. It will supposedly begin its second phase of refits to support STOVL fighter operations soon.
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Flattop Fiesta @flattopfiesta.bsky.social · 07/10/2026
Clouds have finally cooperated to show the aircraft carrier USS George H.W. Bush at anchor near Phuket in today's Sentinel-2 satellite images.
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Flattop Fiesta @flattopfiesta.bsky.social · 07/10/2026
Chinese aircraft carrier Fujian at the Yulin Base near Sanya visible in today's USGS Landsat imagery. No new movements here I just liked the natural composition with the ship peaking out from the clouds and the haze.
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Flattop Fiesta @flattopfiesta.bsky.social · 06/10/2026
A similar view of the USS Abraham Lincoln in today's Sentinel-3 satellite images. Still working on the best way to illustrate the ship over the one or two 300m^2 pixels in which it appears. Proximity to Guadalupe island also shows how the script segments land from water and renders land "normally."
ndwi = index(B06,B17);
if (ndwi>0){ //water
val = 12*Math.log10(1+B11+B16+B18+B21);
return [2.5*B08+val,2.5*B06+val,2.5*B04+val,dataMask*0.85];
}
else { //land
  return [5*B08,5*B06,5*B04,dataMask*.85]
}
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Flattop Fiesta @flattopfiesta.bsky.social · 06/10/2026
Heavy cloud cover on the Landsat once again obscuring a view of this region. [I do appreciate that they seem to be having a really great run of same-day Landsat image availability on Copernicus browser the past few weeks]
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Flattop Fiesta @flattopfiesta.bsky.social · 06/10/2026
HMS Queen Elizabeth visible in today's Sentinel-1 synthetic aperture radar images, continuing its operations near the mouth of the Bristol Channel. [finally a decent radar image of the ship with clear corner reflections on both islands and the ski-jump]
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Flattop Fiesta @flattopfiesta.bsky.social · 06/10/2026
French amphibious helicopter carrier Tonnerre visible through the haze in the IR channels at the port of Marseilles in yesterday's Sentinel-2 satellite imagery. Its sister ship the Mistral is apparently on the move again as well on its West African deployment, having departed Dakar this morning.
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Flattop Fiesta @flattopfiesta.bsky.social · 06/10/2026
USS Abraham Lincoln continues exercises in the Pacific ahead of an anticipated return to San Diego later this week. [No significant new developments here but experimenting with design options for annotating single-pixel blips in Sentinel-3 data, unidentifiable save for AIS crossreferencing]
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Flattop Fiesta @flattopfiesta.bsky.social · 05/10/2026
US Navy aircraft carrier Dwight D. Eisenhower visible in last night's Sentinel-1 radar images. The ship returned to port this morning pending an investigation of a landing mishap several days ago.
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Flattop Fiesta @flattopfiesta.bsky.social · 05/10/2026
The Queen Liz was in roughly the same spot in yesterday's radar images so I elided posting about it since the radar image was a bit messy. @navylookout.bsky.social posted an image showing the ship pasing St. Ives this morning but there were too many clouds to see it on the Landsat or Sentinel
HMS Queen Elizabeth near St. Ives via x/@NavyLookout
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Flattop Fiesta @flattopfiesta.bsky.social · 05/10/2026
[that same example with some contrast stretching. usually too lazy to do it in-browser.]
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Flattop Fiesta @flattopfiesta.bsky.social · 05/10/2026
Using just the one image as an example, I went through all 21 channels of Sentinel 3 data and found a few with good contrast ratios. Over cloudless and calm seas the scaled sum of these channels does a good job of making the ships pop out. Might make for a nice background to plot AIS data against.
gain = 20;
val = gain*Math.log10(1+B11+B16+B18+B21);
return [B08+val,B06+val,B04+val,dataMask*.75];
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Flattop Fiesta @flattopfiesta.bsky.social · 05/10/2026
USS Ronald Reagan visible in the same imaging stripe, having headed south along the coast from Bremerton, Washington over the past few days. [I'd initially thought this was the Roosevelt, sticking on a few days in the region before heading into the Pacific for its deployment]
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Flattop Fiesta @flattopfiesta.bsky.social · 05/10/2026
USS Abraham Lincoln visible in today's Sentinel-2 satellite images, conducting an underway resupply with an auxiliary ship west of the Baja. [may return to this one and annotate the auxiliary ship if I can narrow it down]
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Flattop Fiesta @flattopfiesta.bsky.social · 04/10/2026
Oh! That's neat. Contrails have only led me to a ship just once --the Charles de Gaulle. Just revisited that day and the same trails were indeed visible an hour earlier on the Sentinel-3 pass.
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Flattop Fiesta @flattopfiesta.bsky.social · 04/10/2026
The 300 meter pixels of the Sentinel-3 satellites are pretty useless for shipwatching but I've still always been curious what the limits are. Yesterday gave me a natural experiment with a cloudless ocean patch. The ship and its wake are indeed a faint smudge, unidentifiable without the AIS track.
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Flattop Fiesta @flattopfiesta.bsky.social · 04/10/2026
Reporting shows the carrier and one of the escorts (the Delbert Black) have posted up in Phuket, while it appears the other escort has continued on through the straits.
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