Entries tagged as ISS

Today’s “The Toon-Box”

A more successful tracking of ISS

ISS as seen from Naju in April 12, 2018

After several days of clear skies, clouds have been rolling in for the past two days. Amazingly, they did thin out for a few hours in the evening, enabling me to see the ISS for two consecutive days under good conditions. Tracked observation on April 11 failed due to low battery on the telescope, but I was better prepared on April 12 and made a successful tracking.

The International Space Station was 546km away from me at the closest approach at 19:38:03 (408km altitude, -3.6 mag brightness), so the second photo from the bottom right is representative of this. It is coincidentally the clearest photo I got. You can identify many of the modules - starting from the Zvezda module on the top and moving down, you can see the Zarya module in the center with two radiator panels side by side. On the bottom, you can see the cluster of Columbus-Harmony-Kibo modules in the center, with large solar panels on each end. The bright spot is likely where the SpaceX Dragon spacecraft from the CRS-14 mission is currently docked at.


As I have captured several hundreds of frames, it was sufficient enough to arrange them into this 34-second video clip. I have hosted the file on the website, and it should be watchable on a modern browser.

Telescope: Celestron NexStar 6SE + X-Cel LX 9mm eyepiece
Device: iPhone X (afocal)
Settings: 28mm - ISO 400 - 1/1500s - f/1.8
Filters: None
Date/Time: 2018-04-12 19:37-19:38 KST
Location: Naju, Korea
Photos processed with PIPP 2.5.6 and RegiStax 6.1.0.8
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ISS and Rigel as seen by iPhone X

Composite of 50 frames showing ISS making a pass near Rigel (35% size)

The International Space Station was to make a very close pass to Rigel, one of the brightest stars making up the Orion constellation, last Saturday evening where I live. The separation at the closest point was around 0.055°, making it look like the space station passing right over the star to the naked eye. Instead of manual tracking, I decided to fix the telescope on Rigel and record the pass with iPhone X's 4K 60fps video mode. A total of 50 consecutive frames captured the rapid movement. The windy condition, coupled with relatively low angle (35.6°) blurred the results a lot, so I should try this technique again at a higher angle.


Here's the rotated video of the pass, once at the original speed and once at the slow speed.

Telescope: Celestron NexStar 6SE + X-Cel LX 9mm eyepiece
Device: iPhone X (afocal)
Settings: 28mm - ISO 880 - 1/1500s - f/1.8
Filters: None
Date/Time: 2018-03-24 20:00:59 KST
Location: Naju, Korea

Watching ISS with telescope, 2nd try

International Space Station observed on July 30, 2016
ISS pass, animated

When you try to keep up with fast-moving objects with the manual control of the telescope motors, the lack of fine-grained steps become a big limitation. Speed 6 moves at about 0.267 degrees/second and 7 at 1 degree/second, while the International Space Station moves at a speed that is somewhere in between, depending on the distance. To alleviate this slightly, practice and preparation were needed. I fixed the finder scope misalignment and added a camera mount to the telescope. iPhone 6 Plus was placed on the mount to act as a secondary finder scope, much like what I did on my Canon SX50 HS camera three years ago. These made it much easier to have the telescope point at the International Space Station.

As a result, I managed to photograph about 220 frames of the station in two minutes this time, enough to show the movement like the one I did with the old camera two years ago when I came to Naju. The space station was farther away and a lot dimmer (504km vs 685km, -3.5 mag vs -1.6 mag at culmination) than the previous attempt with the telescope, meaning less details. Even so, I think I was able to identify the SpaceX Dragon spacecraft that went up for the CRS-9 mission, which was attached to the bottom of the Harmony module just ten days before.

Telescope: Celestron NexStar 6SE + X-Cel LX 9mm eyepiece
Device: iPhone 6S Plus (afocal)
Settings: 29mm - ISO 720 - 1/1400s - f/2.2
Filters: None
Date: 2016-07-30 KST
Location: Naju, Korea
Stacked with PIPP 2.5.6 and RegiStax 6.1.0.8

Photos: 10 / 9 / 12 / 6 / 9 / 12 / 28 / 4 / 10 / 14 / 8
Time: 20:18:58 / 20:19:07 / 20:19:12 / 20:19:26 / 20:19:39 / 20:19:41 / 20:19:45 / 20:19:50 / 20:19:58 / 20:20:06 / 20:20:12

Tracking ISS with a telescope

International Space Station observed on June 17, 2016

Directly imaging a fast-moving object in the sky like ISS by tracking it manually becomes more difficult with higher magnification. I could barely manage it with the Canon SX50 HS camera with 1.46"/pixel resolution. Using iPhone 6S Plus on the NexStar 6SE telescope with a 9mm eyepiece gives 0.31"/pixel resolution, making the field of view nearly 5 times narrower. Indirect method, which images the moment when the ISS passes in front of another celestial object, is easier because the telescope is focused on a fixed location. This is what I did a year ago. But such opportunity is much harder to come by, so I eventually decided to give the direct method a try with the telescope.

There were many uncertainties, such as what camera settings I should use on my iPhone and whether the telescope's motors would be fast enough. I would have to make guesses and hope for the best. To increase the chances of catching the moments at a high resolution when it entered the view, I used the 4K (3840x2160, 8.3MP) 30fps video recording mode with highest ISO and fastest shutter speed possible. One thing I did manage to "tie down" was the iPhone itself. The Universal Smart Phone Adapter from Modern Photonics that arrived in the mail just in time was the best solution I tried for attaching the phone to any eyepiece I had.

In the end, I was able to capture 22 frames in total out of about 100 seconds of recording. Targeting the space station with a non-magnified finder scope turned out to be quite difficult and focusing was also somewhat tricky. I need more practice to nail these down better. Fortunately, the motor was more than fast enough and the camera settings worked out. Plus, the processed results already outdid the ones from SX50 HS - major parts of the station are much more recognizable. They also explain what I was looking at in the old blurry shots. Looks like I'll be trying more of this in the future.

Telescope: Celestron NexStar 6SE + X-Cel LX 9mm eyepiece
Device: iPhone 6S Plus (afocal)
Settings: 29mm - ISO 720 - 1/1400s - f/2.2
Filters: None
Location: Naju, Korea (time in KST)
Stacked with PIPP 2.5.6 and RegiStax 6.1.0.8

#1: 9 photos @ 2016-06-17 20:39:38
#2: 5 photos @ 2016-06-17 20:40:03

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