Entries tagged as telescope

Nikon P1000 observes ISS-Sun transit

Nikon CoolPix P1000 observes the Sun next to Celestron NexStar 6SE telescope

Encouraged with the results from the previous observation, I took the Nikon P1000 outside during the day to take the photos of the ISS crossing in front of the Sun. Last time I was able to see the transit at home was three and a half years ago. I also got my Celestron telescope out as a backup in case any one of the equipment failed to record the phenomenon. The camera needed a solar filter like the telescope, so I bought an ND100000 glass filter online for US$40 that provided the same amount of light reduction.

Full-resolution composite of the ISS passing in front of the Sun on November 3, 2018 (click for the full photo)

Although the P1000 has burst mode, it can only take seven photos in a span of a second. The window of opportunity was too narrow, so instead of taking the risk I used the 4K 30fps video capability instead. It would sacrifice image quality, but I was sure to get the shot if the frame and focus were right. And sure enough, the transit was captured successfully as you see above.

Stacked image of the ISS shows the details

The result may not be not quite as sharp as using a telescope, but much of the features of the space station were distinguishable. Perhaps I should try the burst mode the next time I get the opportunity to see if that makes a difference.

Device: Nikon P1000
Settings: 3000mm - ISO 400 - 1/500s - f/8
Filters: ICE N100000 (Neutral Density 16.5 Stop)
Time: 2018-11-03 10:48:02 KST
Location: Naju, Korea
17 photos processed with Pixelmator and RegiStax

Mars at Closest Approach in 2018

Mars as seen in 10-minute intervals starting from the midnight of August 1, 2018

Mars comes close to Earth every two years or so, but due to the elliptical orbit the closeness varies a lot. It came as close as 0.373 AU in 2003, while it was 0.674 AU away at its approach in 2012. The closest approaches happen every 15 or 17 years, and the latest one happened on 16:50 KST, July 31, 2018, at a distance of 0.385 AU. The next one will happen in 2035. Since this year's occurrence happened during the day, I did the next best thing and got my telescope set up that night to take a good look.

Unfortunately, Mars is experiencing a planet-level dust storm since early June and it has not subsided yet. A peek at the planet during last week's lunar eclipse indeed showed a mostly uniform orange disk, confirming my fears. I wasn't about to give up, so I got my Baader filter out and hoped for the best. Thankfully, the two-hour shooting session did not go to waste as the hours of post-processing finally revealed some discernible surface details, as you can see here.

You can even observe the planet visibly rotating in this video that incorporates all the photos I took. It's similar to what I made two years ago, but the continuous shooting made for a more fluid animation.

Telescope: Celestron NexStar 6SE
Device: Sony A5000 (prime focus)
Settings: (1500mm) - ISO 100 - 1/100s - (f/10)
Filters: Baader Moon & Skyglow
Time: 2018-07-31 23:59 - 2018-08-01 01:50 KST
Location: Naju, Korea
481 photos processed with PIPP 2.5.9 and RegiStax

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

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

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

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