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ISS and Capella photo op planning

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#1 tjensen

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Posted 27 November 2012 - 02:40 PM

OK, I'm not sure where to post this, but I figure this is a good place to start...

Calsky is predicting an occultation of Capella from my location by the ISS on Friday morning and it sounds like a perfect photo op. Now I'm not generally a satellite photographer but this just sounds like too good a chance to pass up. A known location and a bright start to focus on before imaging. Now... anyone have any advice on how to pull this off?

I was thinking of setting up my 10" LX200GPS with the T2i and recording video. I was also thinking of putting the Flea3 on the C14. In both cases, I was just going to center on Capella and let the ISS fly thru the FOV. I'm not sure that I would get more than one or two frames with the station, even at 60 fps (max for the DSLR) but might with the Flea3 at 100 fps.

Anyone have any thoughts?

Cheers

#2 bunyon

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Posted 27 November 2012 - 02:49 PM

What is the imaging chip on the hyperstar? Could you attach the Flea 3 to the Hyperstar?

Otherwise, your 10" at prime and the Flea.

Whatever you do, good luck!

#3 tjensen

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Posted 27 November 2012 - 03:31 PM

Hey Paul,
The Hyperstar is set for the DSLR. Not sure I could get the Flea3 to fit it. If I did, I don't think I would get enough resolution at F2.
So you're thinking the wider FOV of the 10" with the fast frame rate of the Flea3?

#4 mikotoy

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Posted 27 November 2012 - 04:00 PM

Hey Paul,
The Hyperstar is set for the DSLR. Not sure I could get the Flea3 to fit it. If I did, I don't think I would get enough resolution at F2.
So you're thinking the wider FOV of the 10" with the fast frame rate of the Flea3?


Flea3 at F10 on your C14 is going to yield a very small FOV - ~2.6 x 3.5 arc minutes. You better be very precise with it :)

I would go by way of DSLR at prime and use 1080p resolution in movie mode. @F10 on your C14 that should give you a FOV of ~4.5 x 8 arc minutes.

#5 mikotoy

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Posted 27 November 2012 - 04:08 PM

... since you are already centred on Capella, F10 with the flea3 shouldn't be too bad. Do you know how far off of Capella the ISS will make its pass or is it directly on top of it?

#6 tjensen

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Posted 27 November 2012 - 04:11 PM

Well, if CalSky is right... and it is going to occult Capella, or be very close to it, then aiming shouldn't be an issue.

I do like the idea of the wider FOV that the DSLR provides, but I'm worried about frame rate. At 24-30 fps in 1080p mode, I'm not sure how many frames (if any) would contain the ISS.

I think there are a couple of flybys over the next few nights. I'm not sure they are above my treeline though. I'll have to get out and see and maybe test a few things.

#7 bunyon

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Posted 27 November 2012 - 04:21 PM

Yeah, I was thinking a wider FOV would get you more frames. Will ISS be illuminated? And how long does it take to cross 3'?

It may not work anyway. Looking at threads where they get ISS images, they manually track it so they get minutes of frames with the ISS on chip. I think you use the 10 or 14, center and focus on Capella and let it rip. You get the number of frames you get.

#8 mikotoy

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Posted 27 November 2012 - 04:26 PM

That was my concern was the lower frame rate by using the DSLR.

Too bad we couldn't get the Flea3 connected to th Hyperstar unit ... nice FOV (~17x22 arc minutes) with a nice high frame rate. Anyone want to mock up a c-mount to DSLR adapter? :)

#9 zAmbonii

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Posted 27 November 2012 - 05:12 PM

Here are my thoughts.

1) The night before....and the day of the pass make sure to recheck calsky because their estimates may have changed on where the ISS is going to pass. Also make sure you have your Lat and Long entered as accurately as possible. The difference of 1km can result in a big difference in the sky where the ISS could set to pass. You don't want something like this to happen when the big moment comes :).

2) Calculate the FOV of the camera on your scope and then you can probably calculate just how long the ISS should be on chip during the pass using the calsky FOV and holding your mouse over the ISS track to get the time at different points. This May help you with the framerate you might want and whether to do the DLSR or Flea.

3) depending on the FOV and your feeling on how accurate the calsky prediction is you may want to have the ISS pass through on the short side of the chip, or orient the chip diagonal to the path of the ISS (greater chance of getting it on the chip).

4) THIS MAY BE THE MOST IMPORTANT THING HERE. Depending on the pass, there may be a HUGE difference in brightness of Capella and the ISS. You are going to have to decide on how you want to handle this. Calsky should have an estimate on how bright the ISS should be on the pass, and it may be guesswork on just what settings you may want to use. I'ts going to be tricky to get the settings right so you can see both the star and the ISS in the video if there is a big difference in brightness.

#10 tjensen

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Posted 27 November 2012 - 05:41 PM

Well they've gone from occultation to "close to" which if Starry Night is accurate is a full degree away. So we'll have to see how things change by Friday morning. Might be a moot point anyway since the weather might be iffy. And I'm not too sure about the trees yet. May have to try it "by hand" just to see what happens.

#11 Sunspot

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Posted 27 November 2012 - 06:20 PM

You don't happen to have a telecompressor to put on the Flea3 with the C14 do you? It would give a wider field and a better chance to catch the ISS. Just a thought.

#12 zAmbonii

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Posted 27 November 2012 - 09:05 PM

Don't trust Starry Night, It has never been accurate at all for me for ISS positions when I try to compare it with what calsky has forecast.

#13 tjensen

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Posted 28 November 2012 - 07:58 AM

Just got a new CalSky update and they are saying "may occult" again. Still worried about elevation. I may have to go to the 10" just so I can position the scope so I can see Capalla. CalSky is saying the separation is 0.027* So I'll have to do some math for various FOV. The ISS angular velocity is 1*/s so it won't be in the FOV very long.

Hey Paul, as a matter of fact, I do have a focal reducer for the Flea3.

#14 Koen Dierckens

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Posted 28 November 2012 - 09:24 AM

Hello,

Last summer I tried to capture the ISS transiting the Sun after CalSky attended me to the event.
I used a CPC925 with Focal reducer 6.3, so I got a FL of 1480mm. With this setup, the Sun just fits completely on the CCD.

I used a countdown timer on my iPhone that alerted me 5 seconds before the predicted time, So I could start taking pictures right before the event. The prediction of Calsky was right on! I could see swoosh the ISS past the Sun through the viewfinder.

The transit lasted approx. 0.6 seconds. I used a Canon 50D, which can make 6 images per second in burst mode. I ended up with 4 images where you can see the ISS.

I agree that the most challenging part will be to find a correct exposure time if the trees and clouds don't spoil your view.
I wish you lots of success with your attempt!

edit: concerning the exposure: keep in mind you always can take a picture before or after of Capella with good exposure values for the star and use PhotoShop to combine with the image of the ISS. You won't have a chance of retaking a picture of the ISS if it is not exposed properly.

#15 tjensen

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Posted 28 November 2012 - 11:40 AM

The predicted magnitude is -3.2 so it will be very bright.
If I can manage it, I'll try the Flea3 on the C14 and the T2i on the 10". I have no idea about exposures. I'll just have to cross my fingers and hope for the best. I can't even try Venus because of trees.

#16 Mike Phillips

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Posted 28 November 2012 - 02:13 PM

Yes, I too get "close to" and the centerline is just south of Holly Springs. I think this would be COOL, but can't pack anything and setup in a field. I'd still love to catch the ISS, perhaps this is a good week to try.

Thanks for the heads up Tim!!!

Mike

#17 tjensen

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Posted 28 November 2012 - 05:51 PM

OK... here is my plan... T2i on the C14, Flea3 on the 10" with a focal reducer. When I plug in my exact coordinates, the track in Starry Night falls within the FOV of the Flea3 without the reducer with Capella centered.

Tomorrow morning I'll see if I can find a spot in the back yard that actually allows me to SEE Capella. Keep fingers crossed.

This could be fun!!!

#18 Jason H.

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Posted 28 November 2012 - 11:03 PM

Looks like you'll be catching it right before the move.

Space Station Turning Towards Sun For Experiment (on Dec. 1)

http://www.redorbit....eriment-112812/

Have fun!

Jason H.

#19 tjensen

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Posted 29 November 2012 - 06:40 AM

Looks like I can see Capella. I might have to cut down a tree for the C14, but that's a small price to pay :grin: Now as long as the weather cooperates...

#20 Koen Dierckens

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Posted 29 November 2012 - 08:41 AM

Fingers crossed :jump:

#21 Jim Chung

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Posted 29 November 2012 - 11:43 AM

Tim,

I've done several ISS transits of the Moon & Sun and I would advise on a wider field because you might miss is entirely otherwise. You must be exactly on the Calsky centerline and then sometimes they are still a little off. This past summer I was prepared to image the ISS at about 2000mm focal length with my 2/3" sensored Point Grey Research camera but decided to hedge me bets and image at only 1000 mm. It was the right decision because even though I was exactly on the centerline the ISS transited the Sun at a very slightly lower level and I would have missed it at the high focal length/FOV.

Getting the right exposure will be tricky since the ISS can be quite bright and is easy to overexpose and thus lose detail. It's easier to capture a Lunar or Solar transit because both those bodies will always be brighter and exposing them correctly will always ensure a sharp silhouette capture of the ISS.

If you're using the 640x480 Flea then I would use a much shorter focal length instrument because even if you are lucky to get it, the speed of the ISS will only allow it to appear in one frame.

With DSLR .... I'd still hedge my bets and get a focal reducer on the C14 or the 10" - and have both cameras running a couple of minutes before predicted time although you have the advantage of actually seeing the ISS in the sky with the naked eye well before it crosses Capella.

#22 tjensen

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Posted 29 November 2012 - 12:56 PM

Hey Jim,

Thanks for the advice. Yes, I've considered all those possibilities. I figure the ISS will be in the FOV of the Flea3 for about 0.3 seconds and I was going to run it at 100 -120 FPS hoping for the ISS to show in a few frames.

I do have a focal reducer for both telescopes as well as a thread in 0.5 reducer for the Flea3. I'm going to set up tonight so I might see what kinds of images I can get with the reducers stacked. I think I'll take your advice and put the 0.6 on the C14 along with the T2i. (I'll have to get out my chainsaw first).

Focus won't be an issue with Capella right in the FOV... but exposure will. I was going to use the Moon as a guide there and hope for the best. It will be tricky but I don't have any other choice. At least, I haven't thought of any.

I'd love to do a transit. But they don't seem to happen very often. At least from my location.

I'm open to any and all suggestions at this point so please feel free...

#23 FoxK

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Posted 29 November 2012 - 02:29 PM

I'd go an entirely different route. Although its ok to use Capella as a guide to get a perfect focus (which is essential), I wouldn't use it as the only aimpoint for getting frames of the ISS. I went through all this years ago and found the best method is to precisely match your finder with what is on the camera, ie, image capella, then move the finder so that whatever the finder is pointing at, the camera is imaging. I actually went out and bought a good 50mm crosshair illuminated finder for this........when I move the crosshairs onto the ISS, I know I have a really good chance of having a few frames at least, of the ISS...usually I have a few HUNDRED to choose from....so many that I can use registax to process a few frames in a row to get a better image. If you have a good open field view of the West, then you can start imaging very early in the transit. This way you have more room for error and in my opinion, its inevitable that the first few tries produce not so great results but are useful in that you can get a good idea of the correct exposure based on this result. If you use the crosshair method, you can start imaging early in the transit when it is less bright, up until it is overhead and beyond, where it is VERY bright....the point being that you will be imaging the ISS though a variety of brightnesses so hopefully some will be correct exposure.

Posted Image


If you focus and aim right at Capella, then there's no room for error. Any computer hiccup and you'll miss it. With that F/L you prolly get less than 10 frames but Its ok if you wanna try this way though.....its less work trying to keep the ISS in the crosshairs but I NEVER go that route anymore and using the crosshair method, I now get a 100% success rate (due to knowing the EXACT correct exposure per given overflight brightness. It took a few tries to get it down pat however. Oh, and because you don't want blurring, you're gonna want at least 1/1000 shutterspeed. I use an 80mm ED refractor with a 2x barlow....1/1200 exp and gain about 3/5 to full is about the right settings in my case and might be a good guide for you.

Posted Image


Good luck!

#24 tjensen

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Posted 30 November 2012 - 08:06 AM

Well when I checked this morning, CalSky had changed it's mind to "close to" Capella. So, in spite of Murphy stopping by (drive issues, focus, forgetting to lock the mirror, and FOG!) I decided to try a manual grab... Take my word for it... this is the ISS... though you'd never know it to look at it.

I have two more passes I can try, but it doesn't look like the weather will cooperate. Oh well... maybe next time.

Still... it was an experience.

Stats: Flea3 + 0.5X reducer, 10"LX200GPS,manually pointed 15 frame stack

Attached Files



#25 Koen Dierckens

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Posted 30 November 2012 - 08:33 AM

Murphy always is right behind you, of course, but I think you did a good job.
Following such fast objects with long focal length and the need for manually tweaking parameters like exposure and focus just is damn hard and need practice.

I practiced already a few times photographing passenger jets cruising at 30,000 feet. With them, you have the advantage that when you loose them out of sight, you can use the contrail to lead you back to the plane. (also manipulating camera and telescope in daytime is way easier) But because they are closer, you continuously need to adapt focus as the planes fly over. These sessions made me aware of the challenges when imaging satellites.

I guess that your experience triggered a new interest anyways and I'm sure the next times will give better results. Thanks for sharing your little adventure!






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