So, checking out the ISS Transit Finder site, I had warning that early this morning (like, 4:21 AM) the Chinese Tiangong space station would transit (pass in front of) the nearly-full moon. The weather looked like it was going to be right, so I set my alarm and made sure I was up and ready, camera focus locked in, exposure set for 1/800 second (f8, ISO 800,) smutphone synced closely with UTC (it was off by not quite a second, but I could work with that,) and waited for my moment.
Don’t bother looking at that image up there, since that was a focus test before the event. And I can tell you that the actual transit took 1.01 second, so I was prepared to simply fire off a sequence of frames at the higher frame rate of the 70D (about six a second) starting a little before the time and extending afterward, to ensure that I captured it. Behold!
Booyah! Nailed it!
What? You don’t see it? It’s right there!
Nah, don’t feel bad – it took me four or five passes through the images before I spotted it, and I knew much better where to look, but it’s that little dark smudge right in the center of this crop, above and to the right of the prominent crater (which is Plato.) I was seriously hoping for better than this.
Let’s see it in five frames in an animated gif (pronounced, “ger-VASE“):
Five frames, 200ms delay between each, pegs this at close to real time. But if that’s still hard (and I’m there with you – remember, five passes looking specifically for this,) we have the annotated version, at half-speed:
Better?
Now, a bit of info. These frames were all taken from a tripod with a remote shutter release and overlaid at full res before being cropped down, so the movement you see is not my lousy editing, and might be slightly due to the tripod twitching a little, but it’s mostly a) the moon shifting to the right naturally, as it does, and b) atmospheric distortion, which was egregious this morning. Look at the details on the right side and how they warble and smear – that’s not camera motion, that’s just the distortion from the air. And within a single second too. It’s no wonder I didn’t get anything more distinct from Tiangong.
Funny, when I put this on my calendar to remind me, I failed to notice that today is Not… Really Worth the Effort Day, otherwise I would have skipped it and stayed in bed. I have to tackle things like this from a place with much lower humidity and high-altitude wind shear. Or not at all…