Explanation: After sunset on March 28, the International Space Station climbed above the western horizon, as seen from Wallasey, England at the mouth of the River Mersey. Still glinting in the sunlight some 400 kilometers above planet Earth, the fast moving ISS was followed by hand with a small backyard telescope and high frame rate digital camera. A total of 2500 frames were recorded during the 7 minute long visible ISS passage and 100 of them captured images of the space station. These are the four best frames showing remarkable details of the ISS in low Earth orbit. Near the peak of its track, about 60 degrees above the horizon, the ISS was brighter than the brightest star in the sky and as close as 468 kilometers to the Wallasey backyard.
Very sharp. On Mr Addis' instagram site, he says he was holding the scope and manually tracking with aid of his finderscope.
I own the same make and model of scope, and have never attempted hand held photography with it and certainly not when tracking. Respect. Lucky imaging indeed.
I also have the same make and model of DSLR (although it wasn't used for this APOD) which is a great match to the scope for full disc images of the moon. I enjoyed Mr Addis' moon shots, too ... much more skillfully processed than mine.
Nitpicker wrote: ↑Sat Apr 06, 2019 6:01 am
Very sharp. ...
Respect. Lucky imaging indeed.
Agreed. Even though 96% of his shots missed his target altogether, it is still remarkable that he was able to find and track such a small and rapidly moving target by hand well enough that even a few shots had no motion blurr. Viva the 4%.
Just as zero is not equal to infinity, everything coming from nothing is illogical.
Re: the last question, yes. The ISS makes one rotation per orbit so the cupola is always aimed at the Earth except for specific reasons when they temporarily change the orientation.
There's a number of us amateur astro imagers on Twitter that manually track ISS passes with telescopes then post images or sequences from the pass. This last week as pretty good for viewing from the UK and Western Europe with high altitude passes just after dusk. Here's a couple of mine from last weekend:
Those sequences were from around 250 DSLR frames, processed with software to crop and align on the ISS, rejecting any "misses" and frames where it blurred too much, then put into an animation. Total used frames was about 150 from the pass.
RickyM wrote: ↑Wed Apr 10, 2019 7:24 pmhigh frame rate digital camera. A total of 2500 frames were recorded during the 7 minute long visible ISS passage
5.95 fps is not a high frame rate.
The recording probably didn't cover the full 7 minutes. I would be surprised to learn these individual images were made with exposure times longer than 1/30 seconds.
Edit: I think the APOD author has said these images were exposed for 0.55 milliseconds each.
That all sounds reasonable. A sustained frame rate of 6 frames per second with individual exposure times of 1/2000 second or faster. Pretty typical for satellite imaging through a telescope.
The camera used, is advertised as being capable of up to 60 fps when recording the full sensor through a USB3 port. The frame rate was more likely higher than 6 fps and the video shorter than 7 minutes.