Wesley's Tool-Box

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

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

Mars rotates once every 24 hours and 37 minutes, so the look of the planet would visibly change as you keep an eye on the planet during the night. Owing to the fact that Mars is at its closest to Earth in more than ten years as I write this, this phenomenon had become relatively easy to photograph with my equipment. In fact, yesterday's post already illustrated this point.

However, I wanted to see if this could be made into an animation. So I managed to take photos of Mars in 30-minute intervals in the span of 4 hours. I wanted to stay up longer, but practical considerations like sleep and humidity prevailed. As you can see at the top, I ended up with a total of eight frames after post-processing nearly 3,000 burst mode photos taken with my iPhone 6S Plus mounted on the telescope. They were then put together into GIF animation that you see on the left.

The frames preserve the 2x digital zoom that I used while taking the photos because it allows you to discern the major features of Mars easier. The dark spot that sticks out on the right side of the planet in the first four frames is Syrtis Major Planum. The brighter area at the center of the planet in all the frames is Arabia Terra. Left side of the dark area just below the Arabia Terra is Meridiani Planum, where the Opportunity rover (MER-B) is currently operating (for more than 12 Earth years as of this writing). The dark area to the left of Arabia Terra visible on the last frame is Acidalia Planitia.

Telescope: Celestron NexStar 6SE + X-Cel LX 9mm eyepiece
Device: iPhone 6S Plus (afocal, 29mm - f/2.2 fixed)
Filters: Baader Moon & Skyglow
Location: Naju, Korea (time in KST)
Stacked with PIPP 2.5.6 and RegiStax 6.1.0.8

#1 (114 photos): ISO 200 - 1/25s @ 2016-05-30 22:10-22:11
#2 (116 photos): ISO 125 - 1/60s @ 2016-05-30 22:44-22:45
#3 (142 photos): ISO 100 - 1/50s @ 2016-05-30 23:12
#4 (130 photos): ISO 100 - 1/50s @ 2016-05-30 23:42
#5 (103 photos): ISO 100 - 1/50s @ 2016-05-31 00:10-00:11
#6 (106 photos): ISO 100 - 1/50s @ 2016-05-31 00:39-00:40
#7 (85 photos): ISO 100 - 1/50s @ 2016-05-31 01:09-01:10
#8 (118 photos): ISO 100 - 1/40s @ 2016-05-31 01:40

With a nearly perfect weather returning last night, I set out to point the telescope out the window once again. This time, I installed the Baader M&S filter as I planned last week. It was an excellent time to take photos of the planets - it was not only about 42 to 44 hours away from the closest approach of Mars in 2016, but Jupiter's Great Red Spot was in view. At this approach, Mars will be at its largest apparent diameter since November 20, 2005 and it won't be surpassed until June 19, 2018. For future reference, next closest approach will happen on July 31, 2018 and that itself won't be surpassed until the one in September 2035.


I planned just for Jupiter and Mars at first, but Saturn edged into the view at the left of the window after midnight. In the end I was able to take photos of all three planets in a single session similar to what I did a year ago, except that Venus was replaced with Mars. The filter did seem to work okay, giving me a better look at the clouds of Jupiter and the dark features of Mars.

Telescope: Celestron NexStar 6SE + X-Cel LX 9mm eyepiece
Device: iPhone 6S Plus (afocal)
Filters: Baader Moon & Skyglow
Location: Naju, Korea
Stacked with PIPP 2.5.6 and RegiStax 6.1.0.8

Jupiter (200 photos): 29mm - ISO 160 - 1/25s - f/2.2 @ 2016-05-29 21:54-21:56 KST
Saturn (200 photos): 29mm - ISO 250 - 1/15s - f/2.2 @ 2016-05-30 00:16-00:17 KST
Mars #1 (150 photos): 29mm - ISO 80 - 1/30s - f/2.2 @ 2016-05-29 22:02-22:03 KST
Mars #2 (300 photos): 29mm - ISO 50 - 1/40s - f/2.2 @ 2016-05-30 00:21-00:22 KST