Wesley's Tool-Box

It seems that I get to see a "great" transit of the ISS in front of the Sun once every year, with the space station appearing large enough to make it look like the letter H. This time, CalSky was predicting a nearly perfect condition at Naju, a near-center pass with an apparent diameter of more than one arc minute (63.1"). With the weather cooperating, I did not want to miss it.

To make sure I did not miss anything, I took out both my Celestron telescope with the smartphone adapter and my SX50 HS camera. I was hoping that at least one of them would catch the occurrence. I hurried with the setup and had everything ready just barely. I let my iPhone 6 Plus start recording the view through the eyepiece of the telescope in 240fps slow motion video, and pushed the shutter on my SX50 HS in continuous shoot mode, all mere moments before the transit.


The SX50 HS captured just one frame, which was sort of expected. The quality was easily better than my previous attempts thanks to the large apparent size. But the real deal was in the iPhone 6 Plus. It had captured 80 frames of the ISS in motion in total, with each frame besting the SX50 HS's efforts. The 240fps video capture truly shined, creating this smooth slow motion video as a result.


Here's the stacked and post-processed composite of the video in a single picture; click it to see it in full resolution. You can appreciate the details of the ISS and the sunspot AR 12339 quite better this way. If you look at the space station up close as seen in the first picture of this post, it's good enough to identify its major features. I've marked them for your convenience.

Telescope: Celestron NexStar 6SE + 25mm eyepiece + 2.5x barlow
Device: iPhone 6 Plus (afocal)
Settings: 29mm - 1280x720 - 240fps - f/2.2
Filters: None
Time: 2015-05-10 13:33:58 KST
Location: Naju, Korea
Stacked with RegiStax 6.1.0.8
- #1: 12 photos
- #2: 10 photos (ISS, each) / 100 photos (Sun)

While I have observed the International Space Station (ISS) making a pass in front of the Sun before, it was at a resort far away from home. Yesterday, I had the good fortune of witnessing a pass right at home. My daughter Celine wanted to help out, so I let her set up the equipment and we went to the parking lot to start photographing. We took the photos of the Sun together, and in three of the frames, the ISS was found crossing in front of the Sun. Here is the composite of the three frames set against the stacked 32 frames I shot in 14 seconds while attempting to capture the transit, both in the annotated and full version.

The last frame was really lucky, as it was taken just before ISS got out of the Sun's disk - 0.1 seconds late and we would have ended up taking two frames instead. SX50 HS's regular burst mode takes a photo every 0.43 seconds, so given the transit time of less than a second, this was the best outcome I could expect.

I do wish the fast burst mode, which can take a photo every 0.077 seconds, could take more than 10 photos at once, though. The transit prediction from CalSky is pretty accurate, but local clock error and human reaction delay can creep in. So I would need it to last at least five seconds or so. I should either wait for Canon to make a superzoom camera that can shoot longer bursts, or install an iPhone 5S, which can do 0.1-second burst shots for several minutes, on a telescope. I'm saying this because I missed the Moon - ISS transit on Saturday while using the fast burst mode.


Anyways, here's the animated version of the transit that illustrates the movement quite well. Come to think of it, this sort of pass would be hard to see in person with binoculars - ISS is tiny and moves quite fast, so unless the Sun is magnified really big, it'd be hard to notice.

Device: Canon SX50 HS
Settings: 1200mm - ISO 500 - 1/1250s - f/6.5
Filters: Baader AstroSolar Safety Film
Time: 2014-03-23 08:57 KST
Location: Suwon, Korea
Base photo: 32 photos stacked with RegiStax 6.1.0.8 (08:57:10 - 08:57:24)
Animation: 5 photos (08:57:16.8 - 08:57.18.5)

Sun is measured to be the most perfectly round sphere occurring in nature. But as the Sun sets over the horizon, it looks more "squished" than usual due to atmospheric refraction. This photo was taken when the Sun's altitude was merely 3.27 degrees.

You can still see the sunspots just fine - AR11960 (top; "sunspot 1960") and AR11959 (bottom; "sunspot 1959") are visible at the lower area. The light blemish at the lower right edge is the AR11957.

Device: Canon SX50 HS
Settings: 1200mm - ISO 80 - 1/40s - f/6.5
Filters: Baader AstroSolar Safety Film
Time: 2014-01-26 17:25 KST
Location: Suwon, Korea
79 photos stacked with RegiStax 6.1.0.8

While I made an unsuccessful attempt to photograph Tiangong-1 space station transit the Sun, I noticed some big sunspots. Sunspots like these cause solar flares, which have been prevalent in the recent months. This particular group of sunspots shown here is called AR 11899, of which the biggest one is casually referred to as "Sunspot 1899". It's about 4 times the size of the Earth. If you click the picture for the full look of the Sun, you can also spot AR 11903 near the middle.

Settings: 1200mm - ISO 250 - 1/1000s - f/6.5
Time: 2013-11-23 13:22 KST
Location: Seoul, Korea
10 photos stacked with RegiStax 6.1.0.8

Yesterday, there was a rare "hybrid" (annular/total) solar eclipse that were visible in parts of Africa and Americas. Unfortunately, it was in the middle of the night in Korea, so I couldn't personally see it. Next solar eclipse that I can see without leaving the country would be in 2016.

So I'm looking back at the solar eclipse that I did see and photograph last year on the roof of the company office. The 24 photographs of the Sun, starting from the lower left (because it was rising) were taken at a 5-minute interval and then put into one image. The eclipse started as the Sun rose over the horizon, and finished just before the work hours. Talk about work-friendly celestrial event.

Camera: Canon EOS 450D
Time: 2012-05-21 06:51 - 08:46 KST
Location: Seoul, Korea