Re: ISS transit over Saturn (APOD) image

From: Thierry Legault via Seesat-l <seesat-l_at_satobs.org>
Date: Sun, 24 Jan 2016 21:00:52 +0100
Hi all, the author has just published this text on the apod forum:

Hi,
it's Julian Wessel (J.W.Astronomy)
To make things clear I wanted to say that the 
APOD picture of Saturn and ISS is a composition 
of 2 Frames from different capturing session. 
They're both overlayed and processed to make the event as detailed as possible.
I'm sorry to all the astronomers feeling 
betrayed, this was not my intention. I just 
wanted to top my Jupiter transit and failed by overprocessing this image.
Nevertheless I will prove that it's possible to 
make this catch as perfect as shown. It's all a 
matter of planning and knowing his equipment. And 
I know I can do this. I'm one and a half year 
into astrophotography now and this is a mistake I 
won't do again! I've learned from it.
Sorry!

In addition, the famous planetary imager 
Christopher Go said that since we are far from 
Saturn opposition, there should be the shadow of 
the disk on the rings (on the right side). He 
thinks that Saturn was taken during last opposition, in May.

:(

At 20:50 24/01/2016, Jon . via Seesat-l wrote:
>Hello all; Seeing the last messages on the list 
>I've thought I'ts interesting to show a 
>conversation that some astrofriends and I had 
>last days about this "photo". The following 
>information was made and compiled by Dani 
>Caxete, Fernando Cabrerizo, Manu Arregi and 
>myself. Name of the author: Julian Wessel. The 
>APOD image was released the 2016 jan. 22: 
>http://apod.nasa.gov/apod/ap160122.html The 
>video is available here: 
>https://www.youtube.com/watch?v=OV7iGt0AH_U The 
>blog post of the author: 
>http://jwastronomy.com/news/ISS-transit-in-front-of-Saturn 
>The equipment (setup): 
>http://jwastronomy.com/me/equipment Transit 
>data: Date: 2016/01/15 Time (taken from the 
>video): 07:34:32.000 UTC (Real time of transit: 
>07:34:21:569 UTC) Place: 51.826903, 7.431114, 
>57m (WGS84), +-100 meters. Celestial 
>coordinates: -Saturn at transit time: RA 
>16h45'17", DEC 20º41'02" (J2000) -Saturn's 
>angular size: aprox: 15.5" ISS data: -Celestial 
>coordinates at transit time: RA 16h44'41", DEC 
>-20º37'51.8" (J2000) -Obs-ISS distance: 
>1145.302Km -Mag. of ISS: +1.3 (V),30x20m -ISS's 
>size: 05.4" (based on mcnames archive, by Mike 
>McCants). Part one: ISS's trajectroy respect 
>Saturn. Please see the following capture: 
>https://dl.dropboxusercontent.com/u/32266013/iss1.PNG 
>This capture shows that taking the (practically) 
>exact place showed on the video taken from 
>calsky.com, the ISS passes a bit higger than 
>Saturn, about 1min 29 arcseconds from the center 
>of Saturn. This can be seen on the video 
>released by the author on Stellarium's 
>simulation. The image of the ISS is not at scale 
>but the ball represents the real size of Saturn 
>despite the rings. See this second image: 
>https://dl.dropboxusercontent.com/u/32266013/iss3.PNG 
>This image shows all orbits published by the 
>USPACECOM between the 13th and 16 of january. 
>The marked one is expected to be the one of the 
>calsky prediction, of 1.3 days old. Even if 
>observer would be placed just in the middle of 
>the transit line (of about 30 meters wide), a 
>0.0 days old orbit released at about the transit 
>time indicates that it would be slightly 
>off-track, inside Saturn but not at center: 
>https://dl.dropboxusercontent.com/u/32266013/iss4.PNG 
>That does not make impossible to be true, but 
>yes that would be extremely "lucky". As those 
>days ISS's orbit is updated up to 4-5 times per 
>day its easy to think that accuracy of those 
>elsets is enough good for reach that conclusion. 
>Part two: ISS and Saturn's size: As mentioned 
>above, there is a mis-match between the size of 
>Saturn and ISS. ISS's size in this case is 
>expected to be of 05'4" of arc, vs 36.5" of size 
>of Saturn. The ISS would be significatly smaller 
>than Saturn, and in the image is about of the 
>same size. The size of Saturn was taken from 
>Stellarium, and the size of the ISS is taken by 
>file mcnames, using Heavensat for computing it. 
>Part three: Illumination of the ISS and Saturn: 
>The transit is taken about 4 minutes before 
>local sunrise, and the Sun's elevation is af 
>about 0.4 degrees. It's impossible to obtain a 
>so-dark image with so many colours, specially of 
>the ISS that is on movement. Dani Caxete has 
>noticed also that the illumination of the ISS is 
>incorrect, based of the rings of Saturn and a 
>simulation of Stellarium plus putting over the 
>image: 
>https://dl.dropboxusercontent.com/u/32266013/dani1.jpg 
>As can be seen on this image the sun is in the 
>other direction, that means that the ISS should 
>be illuminated in its other side, and also that 
>the solar panels should be pointing to the Sun. 
>That points that this ISS image was taken at 
>dusk, not at dawn, when its suposed to be taken. 
>Part four: The ISS looks to be copied and 
>pasted: This has been demonstrated by Fernando 
>Cabrerizo. Fernando showed us that the marked 
>frame looks to be copy-pasted: 
>https://dl.dropboxusercontent.com/u/32266013/fernando1.PNG 
>Using advanced photo-edition software in 
>subtraction mode using as reference the marked 
>frame shower in the previous image the ISS 
>dessapears in a perfect black over Saturn: 
>https://dl.dropboxusercontent.com/u/32266013/fernando2.PNG 
>All "frames" looks to be very similar, and for 
>be like that the author should had a never 
>watched seeing in astronomy. Fernando 
>demostrated us that using the differential show 
>mode with the first frame compared with the 
>rest, and taking some care because the image was 
>compressed in .jpg format one of the frames 
>looks to be exactly the same, and it dissapears 
>in a perfect black colour: 
>https://dl.dropboxusercontent.com/u/32266013/fernando3.PNG 
>Here in GIF format, that points all frames to be 
>practically identical: 
>https://dl.dropboxusercontent.com/u/32266013/fernando4.gif 
>Part five: Different distances between ISS 
>shots. Fernando used all the pre-transit frames 
>for make the average of distance between ISS 
>shots. This image plots the first ISS frame and 
>expands it at same distance. There is an obvious 
>distance mis-match, specially in the frame that 
>ISS transits Saturn: 
>https://dl.dropboxusercontent.com/u/32266013/fernando5.PNG 
>This was commented to the author of the photo, 
>and he said that was because a delay of the 
>computer. Part six: Conclusion. All points 
>explained above gives no chance to think that 
>this photo is real. Know what Julian Wessel 
>really made is not easy. My theory is that he 
>took a photo of Saturn and a shot of some frames 
>of the ISS in a high elevation dusk pass and 
>then pasted them together. Anyway its clear that 
>does not accomplish APOD's rules. Sorry if this 
>message does not comply Seesat-L's rules. Jon. 
>€‹€‹ -- Jon, COSPAR 6242, 42.9453, -2.82839, 
>623m, Bitoriano, Basque Country. 
>_______________________________________________ 
>Seesat-l mailing list http://mailman.satobs.org/mailman/listinfo/seesat-l

Thierry Legault
www.astrophoto.fr

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Received on Sun Jan 24 2016 - 14:01:35 UTC

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