Jump to content

  •  

CNers have asked about a donation box for Cloudy Nights over the years, so here you go. Donation is not required by any means, so please enjoy your stay.

Photo

ISS zenith pass, August 4, 2021

  • Please log in to reply
31 replies to this topic

#1 Tom Glenn

Tom Glenn

    Soyuz

  • -----
  • topic starter
  • Posts: 3,640
  • Joined: 07 Feb 2018
  • Loc: San Diego, CA

Posted 05 August 2021 - 04:37 AM

I took this image tonight as the ISS crested 88 degrees above San Diego.  I used the C9.25 Edge HD with ASI224mc, at f/10 with standard UV/IR cut filter, exposure 0.5ms, gain 220, 12 bit capture.  I chose these settings based upon a study of images I've taken over several years, and it proved to be right on the money.  The image is resized 2x.  The scope was manually tracked after releasing the clutches on my equatorial mount, which is incredibly awkward at zenith.  Points of interest include the new iROSA solar panels which are visible at far left slightly interior to the main array (and casting a shadow), as well as several spacecraft docked, including the Nauka module that caused mayhem last week with erratic thruster firing which sent the ISS into a spin that had to be corrected.  

 

ISS-August-4-2021-TGlenn.jpg


  • zjc26138, RNSpeed, John Miele and 35 others like this

#2 Aquat0ne

Aquat0ne

    Vostok 1

  • -----
  • Posts: 191
  • Joined: 23 Sep 2019

Posted 05 August 2021 - 04:38 AM

Wow, impressive as always.

#3 happylimpet

happylimpet

    Fly Me to the Moon

  • *****
  • Posts: 5,948
  • Joined: 29 Sep 2013
  • Loc: Southampton, UK

Posted 05 August 2021 - 05:36 AM

very much appreciate the capture details. great image!


  • Mike Phillips likes this

#4 Quaternion

Quaternion

    Viking 1

  • -----
  • Posts: 531
  • Joined: 08 Dec 2011
  • Loc: USA

Posted 05 August 2021 - 05:37 AM

Great shot of the ISS and all of the new modules/panels.  Did you get a chance to try out Torsten's focus/gain sweeps yet?  I have had work, weather, and wifey conflicts that have slowed down my ISS imaging efforts this summer. Hope to do some more this Fall, and maybe get a shot of Tiangong.



#5 Tulloch

Tulloch

    Gemini

  • *****
  • Posts: 3,410
  • Joined: 02 Mar 2019
  • Loc: Melbourne, Australia

Posted 05 August 2021 - 08:51 AM

Excellent Tom, truly awesome bow.gif .

 

Thanks for the exposure details also :). What do you prefer the set your focus on, the moon, a star or a planet? Or doesn't it matter?



#6 spereira

spereira

    Fly Me to the Moon

  • *****
  • Moderators
  • Posts: 6,512
  • Joined: 21 Apr 2017
  • Loc: Bedford, NH

Posted 05 August 2021 - 08:56 AM

Wow!  Excellent.  

Thanks very much for sharing!

 

smp



#7 RedLionNJ

RedLionNJ

    Aurora

  • *****
  • Posts: 4,638
  • Joined: 29 Dec 2009
  • Loc: Red Lion, NJ, USA

Posted 05 August 2021 - 08:57 AM

Really nice, Tom. This is just a single frame?

 

 

Andrew - aren't they all at infinity? :)



#8 Lopper

Lopper

    Vostok 1

  • -----
  • Posts: 100
  • Joined: 20 Jul 2021
  • Loc: SW Ohio, USA

Posted 05 August 2021 - 11:27 AM

That's an amazing shot, Tom! Thanks for including the exposure details, too.



#9 Tulloch

Tulloch

    Gemini

  • *****
  • Posts: 3,410
  • Joined: 02 Mar 2019
  • Loc: Melbourne, Australia

Posted 05 August 2021 - 05:04 PM

Andrew - aren't they all at infinity? smile.gif

Yeah, I guess it's an odd question lol.gif .

 

I would have thought so too - but the last time I tried to image the ISS I pre-focussed on the moon (as it was the only thing up at the time), and the resulting ISS frames (almost 1000 of them) were all out of focus. Maybe I knocked the focus knob or something, but it was very disappointing. Hence the question ...


Edited by Tulloch, 05 August 2021 - 05:05 PM.


#10 Alfredo Beltran

Alfredo Beltran

    Viking 1

  • *****
  • Posts: 991
  • Joined: 01 Aug 2010
  • Loc: Bogota, Colombia

Posted 05 August 2021 - 10:27 PM

Amazing imageā€¦ and tracking manually!



#11 R Botero

R Botero

    Gemini

  • -----
  • Posts: 3,361
  • Joined: 02 Jan 2009
  • Loc: Kent, England

Posted 06 August 2021 - 02:12 AM

Again superb from you Tom :bow:

#12 Tom Glenn

Tom Glenn

    Soyuz

  • -----
  • topic starter
  • Posts: 3,640
  • Joined: 07 Feb 2018
  • Loc: San Diego, CA

Posted 06 August 2021 - 03:30 AM

Thanks for the comments everyone!  Thanks also for the questions.  I have a lot of interesting discussion and raw data to provide, but I haven't had the time yet to post (this hobby is not my day job, and I needed to address my Saturn post first!).  I plan to add more information either tomorrow or over the weekend.  


  • Tulloch and Aquat0ne like this

#13 Tom Glenn

Tom Glenn

    Soyuz

  • -----
  • topic starter
  • Posts: 3,640
  • Joined: 07 Feb 2018
  • Loc: San Diego, CA

Posted 09 August 2021 - 12:36 AM

Here are some additional data and discussion points.  In answer to the specific questions above, focus can be set on any available object, but what really matters is if your mirror or focuser moves around as you maneuver the scope.  My scope has mirror locks, and so changes in focus are unlikely, although my main concern is collimation, which doesn't hold very well in my scope.  The best you can do is pick a region of the sky to collimate, and then keep your fingers crossed.  

 

I haven't attempted the "gain sweep" feature in FC yet, although for reasons discussed below concerned stacking, I don't feel it will be helpful to me.  Perhaps if you have a mount that automatically tracks the ISS it would be beneficial.  The main problem is that getting sets of consecutive frames of equal quality is somewhat rare, and I don't want to waste any on suboptimal exposures.  I feel very comfortable in the exposure settings I used here for any future passes.  

 

The image presented at the top of the thread is a stack of two consecutive frames, although the benefit over either individual frame is minimal at best (perhaps nonexistent with some tinkering).  There is no doubt, however, that frame stacking is beneficial to ISS imaging.  Many of the best ISS images currently produced in the world are made from stacks containing up to 100-200 frames.  In order to stack that number of frames, it is almost mandatory to have automated tracking, although I have seen some examples of people using dobsonians with manual tracking who are getting many more frames than I am.  Manual tracking on an EQ mount is suboptimal.  

 

Some raw data on the pass: I recorded for about 130s and used PIPP to isolate the frames with the spacecraft.  This produced 300 frames out of 8196 that were recorded during that period, for a hit rate of 3.7%.  My frame rate was only 63fps because I recorded in 12 bits.  Had I recorded in 8 bits I would have achieved 150fps, and more than doubled my frames.  Whether or not this would have been beneficial is hard to say, as the extra bit depth may have helped with dynamic range issues.

 

Here is an example of a raw frame without any changes, and the associated histogram.

raw-frame-linear-TGlenn.jpg

histogram-ISS.jpg

 

If we apply a gamma of 2.2 (our monitors are not designed to display linear data so it looks abnormal) we get the following.

raw-frame-gamma-TGlenn.jpg

 

If we apply some deconvolution and make the background black, we get this:

raw-frame-gamma-decon-TGlenn.jpg

 

The above image is very similar to the one I originally posted, with the original image being slightly sharper because it could accept a bit more deconvolution.

 

Here is an animated gif showing 5 consecutive frames that occurred a few seconds later in the pass.

ISS-5-frames-TGlenn.gif

 

And here is the result if we stack these five frames and apply moderate deconvolution.

ISS-frames-8412-8416-decon-TGlenn.jpg

 

Here is another example of 4 consecutive frames stacked and mildly sharpened.

ISS-4-frames-TGlenn.jpg

 

The recurring theme here is attempting to squeeze as much information as possible out of a bare minimum of frames.  Out of my 300 frames collected that contain the ISS, only about 50% of them occur during the optimal portion of the pass during which the angular size is near maximum.  Of those, they tend to occur in groups of 3-8 consecutive frames.  Unfortunately, most of these sets are unstackable because of inconsistency between adjacent frames.  And because of the fast motion of the ISS at zenith (1deg/s) the change in perspective of the spacecraft is fast enough that anything beyond perhaps a 1s interval is non-stackable.  And even for consecutive frames, the two main causes of image distortion are 1)atmospheric effects and 2)rolling shutter artifacts.  In fact, rolling shutter artifacts cause a small percentage of the frames to be completely unusable, but more common is that differential distortion between two frames causes an apparent shift in perspective when none should occur.  In this respect, cameras with global shutters will yield a higher percentage of usable frames.  But the most obvious factor that would improve the final result of an ISS image is the use of a tracking system that continuously follows the ISS, resulting in the possibility of stacking 100+ frames.  


Edited by Tom Glenn, 09 August 2021 - 12:52 AM.

  • JMP, Dennis_Oz, Kokatha man and 4 others like this

#14 kevinbreen

kevinbreen

    Gemini

  • -----
  • Posts: 3,010
  • Joined: 01 Mar 2017
  • Loc: Wexford, Ireland

Posted 09 August 2021 - 06:19 AM

Great tips Tom, thanks

#15 matt_astro_tx

matt_astro_tx

    Apollo

  • -----
  • Posts: 1,478
  • Joined: 19 Jan 2021
  • Loc: Dallas, Texas

Posted 09 August 2021 - 09:21 AM

Excellent information and images!



#16 JMP

JMP

    Apollo

  • *****
  • Posts: 1,138
  • Joined: 31 Oct 2005

Posted 09 August 2021 - 10:14 AM

Amazing! Excellent work there, Tom!

#17 BeltofOrion

BeltofOrion

    Viking 1

  • -----
  • Posts: 777
  • Joined: 07 Jan 2016
  • Loc: Newfoundland, Canada

Posted 12 August 2021 - 08:27 AM

Great work, Tom!

 

When you manually track the ISS are you looking through a finder scope, or just sighting over the top of the optical tube of the Celestron? 



#18 Borodog

Borodog

    Vanguard

  • -----
  • Posts: 2,419
  • Joined: 26 Oct 2020

Posted 12 August 2021 - 01:36 PM

Here are some additional data and discussion points.  In answer to the specific questions above, focus can be set on any available object, but what really matters is if your mirror or focuser moves around as you maneuver the scope.  My scope has mirror locks, and so changes in focus are unlikely, although my main concern is collimation, which doesn't hold very well in my scope.  The best you can do is pick a region of the sky to collimate, and then keep your fingers crossed.  

 

I haven't attempted the "gain sweep" feature in FC yet, although for reasons discussed below concerned stacking, I don't feel it will be helpful to me.  Perhaps if you have a mount that automatically tracks the ISS it would be beneficial.  The main problem is that getting sets of consecutive frames of equal quality is somewhat rare, and I don't want to waste any on suboptimal exposures.  I feel very comfortable in the exposure settings I used here for any future passes.  

 

The image presented at the top of the thread is a stack of two consecutive frames, although the benefit over either individual frame is minimal at best (perhaps nonexistent with some tinkering).  There is no doubt, however, that frame stacking is beneficial to ISS imaging.  Many of the best ISS images currently produced in the world are made from stacks containing up to 100-200 frames.  In order to stack that number of frames, it is almost mandatory to have automated tracking, although I have seen some examples of people using dobsonians with manual tracking who are getting many more frames than I am.  Manual tracking on an EQ mount is suboptimal.  

 

Some raw data on the pass: I recorded for about 130s and used PIPP to isolate the frames with the spacecraft.  This produced 300 frames out of 8196 that were recorded during that period, for a hit rate of 3.7%.  My frame rate was only 63fps because I recorded in 12 bits.  Had I recorded in 8 bits I would have achieved 150fps, and more than doubled my frames.  Whether or not this would have been beneficial is hard to say, as the extra bit depth may have helped with dynamic range issues.

 

Here is an example of a raw frame without any changes, and the associated histogram.

attachicon.gifraw-frame-linear-TGlenn.jpg

attachicon.gifhistogram-ISS.jpg

 

If we apply a gamma of 2.2 (our monitors are not designed to display linear data so it looks abnormal) we get the following.

attachicon.gifraw-frame-gamma-TGlenn.jpg

 

If we apply some deconvolution and make the background black, we get this:

attachicon.gifraw-frame-gamma-decon-TGlenn.jpg

 

The above image is very similar to the one I originally posted, with the original image being slightly sharper because it could accept a bit more deconvolution.

 

Here is an animated gif showing 5 consecutive frames that occurred a few seconds later in the pass.

attachicon.gifISS-5-frames-TGlenn.gif

 

And here is the result if we stack these five frames and apply moderate deconvolution.

attachicon.gifISS-frames-8412-8416-decon-TGlenn.jpg

 

Here is another example of 4 consecutive frames stacked and mildly sharpened.

attachicon.gifISS-4-frames-TGlenn.jpg

 

The recurring theme here is attempting to squeeze as much information as possible out of a bare minimum of frames.  Out of my 300 frames collected that contain the ISS, only about 50% of them occur during the optimal portion of the pass during which the angular size is near maximum.  Of those, they tend to occur in groups of 3-8 consecutive frames.  Unfortunately, most of these sets are unstackable because of inconsistency between adjacent frames.  And because of the fast motion of the ISS at zenith (1deg/s) the change in perspective of the spacecraft is fast enough that anything beyond perhaps a 1s interval is non-stackable.  And even for consecutive frames, the two main causes of image distortion are 1)atmospheric effects and 2)rolling shutter artifacts.  In fact, rolling shutter artifacts cause a small percentage of the frames to be completely unusable, but more common is that differential distortion between two frames causes an apparent shift in perspective when none should occur.  In this respect, cameras with global shutters will yield a higher percentage of usable frames.  But the most obvious factor that would improve the final result of an ISS image is the use of a tracking system that continuously follows the ISS, resulting in the possibility of stacking 100+ frames.  

I now demand that you make a stereo pair. Pretty please. ;O)



#19 Kokatha man

Kokatha man

    Hubble

  • *****
  • Posts: 15,804
  • Joined: 13 Sep 2009
  • Loc: "cooker-ta man" downunda...

Posted 12 August 2021 - 08:13 PM

I obviously missed this earlier Tom - but a great result with excellent graphics & descriptions...well done! waytogo.gif waytogo.gif waytogo.gif



#20 descott12

descott12

    Gemini

  • *****
  • Posts: 3,423
  • Joined: 28 Sep 2018
  • Loc: Charlotte, NC

Posted 12 August 2021 - 09:08 PM

Stunning!!

#21 Tom Glenn

Tom Glenn

    Soyuz

  • -----
  • topic starter
  • Posts: 3,640
  • Joined: 07 Feb 2018
  • Loc: San Diego, CA

Posted 13 August 2021 - 12:42 AM

Thanks for all of the additional comments and likes folks!  Much appreciated!  As for the request for a stereo pair, I'll look into it, but I'm not sure if I have the right pair of images to pull it off....it would require just the right amount of shift, but also similar quality between images.  



#22 vilchez

vilchez

    Vostok 1

  • -----
  • Posts: 151
  • Joined: 07 Jan 2016
  • Loc: Spain

Posted 13 August 2021 - 03:42 AM

Great catch.

#23 John Miele

John Miele

    Aurora

  • *****
  • Posts: 4,768
  • Joined: 29 May 2005
  • Loc: North Alabama

Posted 14 August 2021 - 10:42 AM

Man these ISS images just keep getting better and better! This one is amazing!



#24 BeltofOrion

BeltofOrion

    Viking 1

  • -----
  • Posts: 777
  • Joined: 07 Jan 2016
  • Loc: Newfoundland, Canada

Posted 14 August 2021 - 10:44 AM

Tom, I'm assuming you could  get the 12bit capture because of the ASI224 camera you used. Have you tried this with your ASI183? If I were to try it with that camera, would the 8bit setting be the best to use, rather than 16? As you know, there is no 12 bit setting on the 183. I also have the ASI294MC with the settings Raw8, Raw16, RGB24, and Mono8. Which would you suggest as a starting point if I should ever get in a position to give this a try? 



#25 descott12

descott12

    Gemini

  • *****
  • Posts: 3,423
  • Joined: 28 Sep 2018
  • Loc: Charlotte, NC

Posted 14 August 2021 - 11:16 AM

Tom, I'm assuming you could  get the 12bit capture because of the ASI224 camera you used. Have you tried this with your ASI183? If I were to try it with that camera, would the 8bit setting be the best to use, rather than 16? As you know, there is no 12 bit setting on the 183. I also have the ASI294MC with the settings Raw8, Raw16, RGB24, and Mono8. Which would you suggest as a starting point if I should ever get in a position to give this a try? 

I normally use my 178 mono in MONO8 but I just recently tried using my 224 color camera in RAW8 and I was pretty pleased. Here it is:

Attached Thumbnails

  • 00562.jpg

  • BeltofOrion likes this


CNers have asked about a donation box for Cloudy Nights over the years, so here you go. Donation is not required by any means, so please enjoy your stay.


Recent Topics






Cloudy Nights LLC
Cloudy Nights Sponsor: Astronomics