Starship Asterisk*

ISS Transits Saturn

Explanation: From low Earth orbit to the outer Solar System, this remarkable video frame composite follows the International Space Station's transit of Saturn. On January 15, the well-timed capture from a site near Dulmen, Germany required telescope and camera to be positioned along the predicted transit centerline, a path only 40 meters wide. That put the camera about 1,140 kilometers away from the space station during the transit and 1,600,000,000 kilometers away from Saturn. A video rate of 42 frames per second follows the orbital outpost moving quickly from lower right to upper left. The transit itself lasted about 0.02 seconds, with one frame showing the station directly in front of the ringed gas giant. Of course, you could also try to capture the International Space Station as it transits Jupiter.

(Editor's Note: Original APOD retracted on January 25.)

Love it!

Wow, the ISS, as big as Saturn, who knew....Nice image and very well planned

Looks like the ISS just missed its docking station. Darn!

Ann

BMAONE23 wrote:Wow, the ISS, as big as Saturn, who knew....Nice image and very well planned

And the ISS would appear 2.8 times larger if it were captured passing directly overhead.

WOW. That took some doing. Locate the path, and it's not straight overhead. That's 22 exposures, so half a second for the complete image. And then to get and exact image of ISS and Saturn lined up.

All I can say is congratulations !!

Amazing!!!

:---[===] *

Bullseye er, Saturn's eye. What a shot!

Try to capture the ISS transiting Jupiter? Apparently it's been done, as the link shows: http://jwastronomy.com/news/ISS-transit ... of-Jupiter

And introduces us the wonderful German word word, "Schnittpunct" , which only means 'cut point', but adds so much to the concept.



But the 'conjunction'of even a major planet with such a petty object (!) as the ISS is nothing compared wit a Five Planet Conjunction, which if the UK's cloudy skies would pass for a while I might see now. http://earthsky.org/astronomy-essential ... rn-mercury A new BBC series, "The Story of China" started last night with an episode on the origins of the Chinese nation, and mentioned the same conjunction in 1574 that led to the fall of the Shang Dynasty. http://www.bbc.co.uk/programmes/b06yglnh The presenter said that it occurred every 500 years, but astronomy websites imply that they happen at less then ten year intervals.

Anyway, I hope we get a good view of it here on APOD!
John

Considering how much easier this would have been to fake (not that a fake would get by the experts), I'm really impressed!

To get the ISS perfectly crossing the planet like that, it seems that one has to:

1. find the right spot (anywhere on a thin line on the Earth),
2. keep the camera aligned steadily on the planet throughout the event, and
3. get the shutter going so that one shot is right on center (It would have been far less satisfying to only have seen the ISS just on either side of Saturn, right?).

As someone who's never worked with advanced equipment, all 3 of those are mysteries to me.

• I wonder where one gets info sufficient to accomplish (a);
• I know people can buy drives to accomplish (b), but I don't know the math and engineering marvels that make them actually work nor even how one operates them; and
• (c), unless you can somehow figure this out on-the-fly just as the ISS is arriving, seems to my intuition as though one could not hope to actually calculate it, but would just have to get lucky (is that true?).

All of this, not to mention things like:

• clouds can wreck this,
• you have to figure out sizing and exposure to get a decently-visible image (which I guess the photographer did in advance with lots of work and practice), and
• what Chris pointed out that I never would have thought of is that for a good size ratio of the ISS and the planet, you don't want just any ISS flyover, you want one at a good distance (or did the photographer care about this?)

Anyway, congratulations to Julian Wessel for that tour de force!

Congratulations Mr. Wessel, amazing shot. Thank you

MarkBour wrote:Considering how much easier this would have been to fake (not that a fake would get by the experts), I'm really impressed!

To get the ISS perfectly crossing the planet like that, it seems that one has to:

1. find the right spot (anywhere on a thin line on the Earth),
2. keep the camera aligned steadily on the planet throughout the event, and
3. get the shutter going so that one shot is right on center (It would have been far less satisfying to only have seen the ISS just on either side of Saturn, right?).

Not to diminish the work that went into this, but it's not that difficult. There are loads of tools that calculate future ISS transits, and these are very precise. The positioning required- a few tens of meters- is well inside normal GPS accuracy. The technically trickiest part is starting the camera sequence so that one exposure is mid-transit (assuming this wasn't accidental... which isn't entirely clear). That requires carefully evaluating your camera in burst mode so you know the exact frame-to-frame timing, as well as any delay from the trigger that starts the sequence. Any decent portable mount will track Saturn with more than enough accuracy to maintain its position on the image for several minutes (and generally, for much longer).

Making an image like this is really about dedication and solid technical competence. Many people are capable of doing it- determining a location, owning good portable equipment, and being willing to travel. For most people, it just seems like too much work!

I'm thinking this photo might not be what it says it is. I noticed that the spacing of the ISS near Saturn seems smaller. Using a ruler on my computer screen, I measured a spacing of about 1.5 inches between most frame grabs, but only about 1.2 inches to the upper-left of Saturn, and about 1.1 inches to the lower-right of it. This does not mean it's a fabrication, but why the difference in spacing?

There are a few points about this image that just don't ring quite right.... capture time 8:34am local time, with sunrise being at around the same time, yet the background is dark? And also telling - Saturn less than ten degrees above the horizon, yet crisp, clear images? I'm sorry, call me Mr Skeptical, but I call this a phoney image. Whovever decided this is worthy of an APOD should do better fact-checking. Things simply don't seem to add up.

Neat composition, though,photoshopped Big time. No question about it.

What's your evidence?

AND, I just overlaid one of the instances of the ISS in the photo onto several other ones with the opacity at about 50% to compare the differences (since they looked suspiciously identical), and indeed, all the instances I compared are identical. That could not happen in reality.

The image is a fake. See APOD's Facebook page for a full discussion.

John

Doc Willie wrote:What's your evidence?

The ISS image has one "space" spot on it where it should not be. It is easy to find. You can't miss it.

As an honest photographer, I get upset when people fake photos to get attention or sell more prints. I have some very good photos (I have been told anyway), but have sold very few. I am not trying much, admittedly.
Here is an astronomy-related photo that I have taken. http://www.fineartamerica.com/featured/ ... rritt.html
And my favorite photo that I have taken. http://www.fineartamerica.com/featured/ ... rritt.html No, the sailboat was not occupied, I just titled it that way. The photo is totally real though.

FLPhotoCatcher wrote:As an honest photographer, I get upset when people fake photos to get attention or sell more prints. I have some very good photos (I have been told anyway), but have sold very few. I am not trying much, admittedly.
Here is an astronomy-related photo that I have taken. http://www.fineartamerica.com/featured/ ... rritt.html
And my favorite photo that I have taken. http://www.fineartamerica.com/featured/ ... rritt.html No, the sailboat was not occupied, I just titled it that way. The photo is totally real though.

You have been told correctly! Those are beautiful shots!

FLPhotoCatcher wrote:AND, I just overlaid one of the instances of the ISS in the photo onto several other ones with the opacity at about 50% to compare the differences (since they looked suspiciously identical), and indeed, all the instances I compared are identical. That could not happen in reality.

The camera was shooting at 42 frames per second. There's about half that many frames on the image we see, so about 1/2 second of exposure. And you expect to see differences in the orientation of the ISS? Do you think it's spinning like a top up there?

Rob

I haven't read any other discussions about this APOD, but I would not be prepared to call this a fake. The most likely explanation for the slight variation in the spacing of the ISS frames, is atmospheric wobble/distortion. The black background at dawn is simple to achieve with the correct exposure time and gain. And I wouldn't say that the image of Saturn is crystal clear, considering a 10 inch scope was used, although it is pretty good for a dawn sky and 15 degrees elevation. I do suspect some level of processing was done, but probably not an excessive amount.

The video is too compressed to tell what's going on, but this image is indeed the same ISS copy and pasted over and over and not a stack of video frames. Even the ISS on top of Saturn is the same.

geckzilla wrote:The video is too compressed to tell what's going on, but this image is indeed the same ISS copy and pasted over and over and not a stack of video frames. Even the ISS on top of Saturn is the same.

Okay, that's beginning to sound like an excessive amount. Giving the author the benefit of the doubt, I suppose the ISS could have been processed by stacking and aligning all the ISS frames to create a better image of it, and then that one image was superimposed on the noisier ISS images from each frame. (Similarly for Saturn, which is how planetary images are typically made, anyway.) Not the worst crime, but perhaps not a decision to satisfy the purists.

I still think it's great.