Wesley's Tool-Box

I went to San Francisco to pick up my iPhone 15 Pro on the launch day, September 22, 2023. The primary advantages of this model over the previous ones are USB-C support and reduced weight. Unless you were getting a Pro Max version, the camera on the Pro series did not get much of a hardware improvement. So when I decided to do some comparison shots with the Harvest Moon photography during the Chuseok holidays, I chose some older models - iPhone 11 Pro and iPhone 13 Pro.

There were expectedly some notable quality differences between the three models. While iPhone 11 Pro does have a three-lens setup like the rest, the telephoto lens is only capable of 2x zoom. As a result, the size of the Moon in the photo was the smallest and least detailed. Both iPhone 13 Pro and 15 Pro have the 3x zoom lens on them, but for some reason the 15 Pro shot a consistently sharper image. Perhaps a slight hardware and software processing differences were at play. In the end, the latest was indeed the best.

Further details of the shooting sessions have been outlined in a separate video.

The two biggest objects orbiting the low earth orbit, International Space Station (ISS) and the Tiangong Space Station (a.k.a. Chinese Space Station or CSS) can be seen transiting the Sun every now and then. But because their orbital characteristics are different, it's hard to see the two like that on the same day within the 200 km range. And it's much rarer for the two to be seen in front of the Sun at the same time. But earlier this month, I found out that I could see the next best thing - seeing the two make the transit from the same location within 14 minutes of each other.

The result of this observation is shown here as a multiple-frame composite. Thanks to the weather, both space stations were photographed clearly and you can make out their distinct shapes - the less dense one is Tiangong. And because the observations occurred within a short timeframe, it's easy to gauge the relative apparent size difference between each other.

Close-ups of the two space stations make this more apparent. The ISS was 53 arc-seconds wide at 521 km away, while Tiangong was 37 arc-seconds wide at 460 km away. The difference in distance shows that Tiangong's orbit is lower than that of ISS. In fact, Tiangong's nominal orbit is around 375 km, while ISS is at about 420 km.

If the ISS was observed at the same distance, it would have been 60 arc-seconds wide. This means that Tiangong, which was fully built a few months ago, is roughly 60% as wide as the ISS and much bigger than what the transit finder website claims. I think that it's showing the size of just the core module (Tianhe), not the entire structure.

Maybe if I get lucky I will be able to spot the two making the transit at the same time in the future. Until then, I'll keep looking.

Device: Nikon P1000
Settings: 3000mm - ISO 200 - 1/1000s - f/8
Filters: ICE N100000 (Neutral Density 16.5 Stop)
Time: 2023-04-07 11:00 - 11:14 KST
Location: Dangjin, Korea
28 photos (14 each) processed with Pixelmator 3.3.2, RegiStax 6.1.0.8, and PIPP 2.5.9