Home · Register · Search · View Winners · Software · Hosting · Software · Join Upload & Sell

Moderated by: Fred Miranda
Username   Password

  New fredmiranda.com Mobile Site
  New Feature: SMS Notification alert
  New Feature: Buy & Sell Watchlist
  

FM Forums | Canon Forum | Join Upload & Sell

1
       2       end
  

Archive 2012 · ISS - Jupiter. Transit capture failure.
  
 
arky
Offline

Upload & Sell: Off
p.1 #1 · ISS - Jupiter. Transit capture failure.


This morning I attempted to capture a transit of the ISS across the face of Jupiter. The seeing was not good and although I was on the predicted (by CalSky) transit path, the actual path missed me by about 300 meters to the east.
The entire transit happens in 1/25 second. I fear I'm not up to the task of triggering the shutter with this amount of precision so I decided to try and capture it on video.
I used a 600D with a C8 telescope (f/8, 1600mm) for the lens. The video settings were 1920x1080 @ 30 FPS, 3x digital zoom, ISO 3200, 1/1600 second.
Here is a frame from the video with the ISS at it's closest approach.





To get an idea of the speed of the ISS, the entire 8 second video (46 MB) can be downloaded from this webpage.
http://sdrv.ms/W7nIpl
Or you can view the video at YouTube quality here:
http://youtu.be/7H2a_43vuz8
The ISS crosses the frame at about the 6 second mark in the video.

-Jerry

Edited on Nov 14, 2012 at 09:25 PM · View previous versions



Nov 14, 2012 at 03:42 PM
mitesh
Offline
• • • •
Upload & Sell: On
p.1 #2 · ISS - Jupiter. Transit capture failure.


Jerry,

That video really shows just how difficult it is to get a great photo of the ISS, especially when you're trying to frame it with another object. Great effort on your part!

Mitesh



Nov 14, 2012 at 03:56 PM
rprouty
Offline
• • • • •
Upload & Sell: On
p.1 #3 · ISS - Jupiter. Transit capture failure.


A lot better than I could have done.

Rod



Nov 14, 2012 at 05:19 PM
Bones74
Offline
• • •
Upload & Sell: Off
p.1 #4 · ISS - Jupiter. Transit capture failure.


Great effort. I wouldn't have a prayer!


Nov 14, 2012 at 07:01 PM
Sarsfield
Offline
• • •
Upload & Sell: On
p.1 #5 · ISS - Jupiter. Transit capture failure.


Cool! Good job considering. I hear the Russians lost communication for awhile today so maybe you could send them the pic to reassure them that the vessel is still okay...


Nov 14, 2012 at 09:11 PM
Pixel Perfect
Online
• • • • • •
Upload & Sell: On
p.1 #6 · ISS - Jupiter. Transit capture failure.


Good effort arky, infinitely better than I could do







Nov 14, 2012 at 09:23 PM
David Baldwin
Offline
• • • •
Upload & Sell: Off
p.1 #7 · ISS - Jupiter. Transit capture failure.


Good Lord, I loved the video, really gives a sense of how fast the ISS is travelling. Very impressive!

Edited on Nov 15, 2012 at 08:06 AM · View previous versions



Nov 15, 2012 at 12:15 AM
Will Patterson
Offline
• • • •
Upload & Sell: On
p.1 #8 · ISS - Jupiter. Transit capture failure.


hahahahah wow! Great video! Kinda funny when I first saw it.


Nov 15, 2012 at 12:19 AM
delthedog
Offline
• •
Upload & Sell: Off
p.1 #9 · ISS - Jupiter. Transit capture failure.


Nice try, sort of looks like a tie fighter from Star Wars.


Nov 15, 2012 at 12:33 AM
BennyR
Offline
• • •
Upload & Sell: Off
p.1 #10 · ISS - Jupiter. Transit capture failure.


Great job, that is very tough.


Nov 15, 2012 at 05:04 AM
 

Search in Used Dept. 



vachss
Offline
• • •
Upload & Sell: Off
p.1 #11 · ISS - Jupiter. Transit capture failure.


I'd never realized that the apparent diameters of Jupiter and the ISS were so similar.

So since you're about 4 diameters away from perfect alignment and you were 300 meters off does that mean you have to precisely position yourself to within less than 75 m to have a prayer of getting the shot you wanted? Isn't that like <1 second of lat/lon? Worse, getting a "clean" shot of the ISS passing through the center of Jupiter must mean that you 'd have to be within 20m or so of the transit line. Does the error in a standard GPS allow this or do you need some higher precision geolocation technique?

It sounds awfully tough to me, and makes the OP's work particularly impressive.



Nov 15, 2012 at 05:44 AM
dolina
Offline
• • • •
Upload & Sell: Off
p.1 #12 · ISS - Jupiter. Transit capture failure.


Sensible direction.


Nov 15, 2012 at 11:58 AM
arky
Offline

Upload & Sell: Off
p.1 #13 · ISS - Jupiter. Transit capture failure.


vachss wrote:
I'd never realized that the apparent diameters of Jupiter and the ISS were so similar.

So since you're about 4 diameters away from perfect alignment and you were 300 meters off does that mean you have to precisely position yourself to within less than 75 m to have a prayer of getting the shot you wanted? Isn't that like <1 second of lat/lon? Worse, getting a "clean" shot of the ISS passing through the center of Jupiter must mean that you 'd have to be within 20m or so of the transit line. Does the error in a standard GPS
...Show more
Excellent deductive reasoning there. Exactly right, that's what my calculations suggest. It does require quite a bit of precision. I still don't know why the line of transit was off it's calculated path.
As I mentioned earlier, I get my ISS orbital event data from the CalSky website:
http://www.calsky.com/
You can select your viewing location by GPS coordinates or on the zoomable map/satellite view.





I did check the satellite view calibration by entering the coordinates (from GPS) into the CalSky interface. It placed the icon precisely at the overgrown turnoff to the farm field where I was.

When I first noticed this event was occurring near me, I began to research the relative apparent sizes and the crossing speed, to get an idea of the precision involved in trying to capture the actual transit.
Like you, I was surprised at the similar apparent size. CalSky supplied an angular diameter of 39.1 sec. of arc for the size of the ISS at the time of the transit. Jupiter's' angular size varies between 30 and 50 sec. of arc. Since Jupiter is near opposition to the sun right now, I figured the size was probably near it's upper limit. Even so, the ISS was going to be a tight fit in the disk of Jupiter.

As for the crossing speed and dwell time over Jupiter, CalSky somewhat cryptically reports the transit to last for .01 seconds. I'm not sure if this is supposed to represent the time the entire ISS is inside the disk of Jupiter or if this time interval is from leading edge contact to trailing edge exit. CalSky helpfully specified the angular velocity of the ISS at the moment of transit as 29.5 minutes of arc per second. Converted to arc seconds that is 1770 arc seconds per second. Since I had already determined that the ISS would 80% the diameter of Jupiter, then it would be ideally at the center of Jupiter with a 10% cushion on each side. So the window for timing the shot to contain the entire ISS within the disk of Jupiter is the time it takes the ISS to traverse 20% of it's apparent angular diameter. 20% of the angular diameter of the ISS is about 8 arc seconds and at 1770 arc seconds per second the ISS should traverse this distance in about 1/220th of a second. In essence, in order to guarantee the ideal capture, with the entire ISS contained within the disk of Jupiter, I would need to trigger a shot within the 4 millisecond window or capture at least 220 FPS. Obviously neither option is really viable.

Lowering my expectations a little, I computed the time it takes from the leading edge of the ISS to make contact until the trailing edge exits the disk of Jupiter. It turns out this window is about 1/20th of a second. I don't think I can trigger a shot within a 50 millisecond window but I can capture video at 30 FPS. So although 30 FPS only gives a 13% probability of getting the ideal shot, it assures at least 1 shot will show them with the edges touching.

I would still like to know where I went wrong. In my opinion, Jupiter would be the perfect backdrop for the ISS to be silhouetted on. It's 5 times further from the sun so it is quite a bit dimmer but it's still bright enough to show the shaded parts of the ISS in silhouette. The moon is either too bright to show much contrast between it and the illuminated parts of the ISS or so dark it doesn't show any silhouette from the shaded parts. When photographed against the sun it is obviously a silhouette only.

This may be an exercise in futility, but I will probably try again if the opportunity arises. Any advice or insight into where I went wrong would be greatly appreciated.

Thanks everyone for the encouraging comments.

-Jerry



Nov 16, 2012 at 12:21 AM
Liquidstone
Offline
• • •
Upload & Sell: Off
p.1 #14 · ISS - Jupiter. Transit capture failure.


Excellent attempt on what looks like an impossibly difficult shot.


Nov 16, 2012 at 01:48 AM
PickledEyes
Offline

Upload & Sell: Off
p.1 #15 · ISS - Jupiter. Transit capture failure.


I have got to admit, it is really something to be able to say you did this, knowing just how much luck you have to have, to capture the winning shot. But to go after the fact, to try to find the reason your shot was off..... Your made of sterner stuff than most, and I hope to see the shot as you envisioned next time!


Nov 17, 2012 at 02:05 AM
BrianO
Offline
• • • • •
Upload & Sell: On
p.1 #16 · ISS - Jupiter. Transit capture failure.


vachss wrote:
...you 'd have to be within 20m or so of the transit line. Does the error in a standard GPS allow this...


When Selective Availablity was canceled by President Clinton in 2000, average accuracy of civilian GPS units went from around 100m during S/A periods to better than 15 meters 24/7. Receivers implementing Differential GPS or using a Wide Area Augmentation System can be accurate to as little as 3 meters.

Repeatability (the ability to return to a specific point) can be measured in centimeters with some modern receivers.

Accuracy can be degraded, though, by many local factors, and inaccurate maps are a leading cause of error.



Nov 17, 2012 at 04:07 PM
stebesplace
Offline
• • •
Upload & Sell: On
p.1 #17 · ISS - Jupiter. Transit capture failure.


That's what 17K miles an hour looks like, no? Very cool!!!


Nov 18, 2012 at 10:08 PM
garjor
Offline

Upload & Sell: Off
p.1 #18 · ISS - Jupiter. Transit capture failure.


Great


Nov 19, 2012 at 12:11 AM
stanj
Offline
• • • • •
Upload & Sell: On
p.1 #19 · ISS - Jupiter. Transit capture failure.


If this is a failure, then I question most of our best achievements

Well done!



Nov 19, 2012 at 03:01 AM
Alex Edwards
Offline

Upload & Sell: Off
p.1 #20 · ISS - Jupiter. Transit capture failure.


Very cool images.

My suggestion to look for where the slight error in the paths is would be in the heigh above the sea level. The predicted path might be based on the projection to zero elevation or to the altitude from a digital elevation model that dosen't exactly match your viewing height.

How high above sea level are you and would that make sence with the 75m?



Nov 19, 2012 at 03:09 AM
1
       2       end




FM Forums | Canon Forum | Join Upload & Sell

1
       2       end
    
 

You are not logged in. Login or Register

Username   Password    Retrive password