Entries tagged as astronomy

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 6.1.0.8

Century's longest total lunar eclipse and Mars

36-photo composite of the July 2018 total lunar eclipse and the trailing Mars (click for higher resolution)

Those living in Korea was able to see the second total lunar eclipse of the year, following the one in January 31. I had multiple reasons to watch this eclipse. There wasn’t going to be another total lunar eclipse visible in Korea for nearly three years (next one is on May 26, 2021). Also, Mars was just past the opposition, shining bright next to the Moon and forming an interesting celestial pair. Finally, the eclipse was billed as the longest in the century, including more than 103 minutes of totality.

Weather cooperated well, and I was able to both observe and record the progress without a hitch. The result is the composite photo above. It was the first time my newly acquired Sony SEL55210 lens was put to use for astrophotography and it performed adequately.

Celine witnesses her first lunar eclipse after waking up early

One minor disappointment was that the Moon was to set below the horizon during the middle of the totality. So I focused on watching it comfortably in the house with my daughter instead of trying to see through every moment. In fact, it was first such eclipse visible through the southerly window since 2011, enabling Celine to see the phenomenon for the first time. She was impressed with how the full Moon progressively got dimmer from the left corner, eventually becoming red from the Earth’s shadow. Next time, I hope I can show her the comeback part.

Device: Sony A5000 + SEL55210 (E 55–210 mm F4.5–6.3 OSS)
Settings: 55mm - ISO 100 - 1/500s to 5s - f/4.5
Filters: None
Time: 2018-07-28 01:12-04:40 KST
Location: Naju, Korea

100-minute tracking of Jupiter

Jupiter and the Galilean moons seen on 00:44, April 20, 2018

Jupiter and its four major satellites (Galilean moons) are good targets for time lapse photography because of the relatively rapid movement. The rotational period of the planet is slightly less than 10 hours, and Io, the innermost of the Galilean moons, orbits the planet in about 42.5 hours. Under good conditions, these things become noticeable over a span of just about an hour.

Shortly after midnight of April 20, 2018, Io came out from behind Jupiter on the left side, while the Great Red Spot was moving towards the back of the planet on the right side after being in the center. These were all captured on my camera as I took 597 photos of the Jovian system over a period of 100 minutes between midnight and 01:40AM. The photos were then stacked and processed in 1-minute intervals (6 photos on average), like the one you see above, then put together into video as you see below.


I think it shows the dynamics of these celestial objects quite well. Now that I have a good grasp of the workflow for making a planetary animation, I should be able to make a similar one for Mars when it approaches Earth close enough to be seen as half the apparent size of Jupiter next July. Before wrapping up, here's a bonus picture of the Jovian system that I took just after photographing the Sombrero Galaxy. You can actually see Io casting a tiny shadow on Jupiter. I thought I would never see that sort of thing on my telescope.

Jupiter and the Galilean moons seen on 01:03, April 19, 2018

Telescope: Celestron NexStar 6SE
Device: Sony A5000 (prime focus)
Settings: (1500mm) - ISO 100 - 1/15s(#1), 1/20s(#2) - (f/10)
Filters: Baader Moon & Skyglow
Time: 2018-04-20 00:00 ~ 01:40(#1), 2018-04-19 01:03(#2) KST
Location: Naju, Korea
597(#1), 6(#2) photos processed with PIPP 2.5.6 and RegiStax 6.1.0.8

Sombrero Galaxy

Sombrero Galaxy seen on the night between April 18 and 19, 2018 (25% size)

I was looking to photograph a galaxy that was shaped distinct enough to look like something other than a blob of fuzzy light ball under limited equipment and conditions. Looking through the available targets, I picked out the Sombrero Galaxy, also known as Messier 104. This is a spiral galaxy in the Virgo constellation that resembles the shape of a sombrero, a Mexican style wide-brimmed straw hat.

As you can see here, the observation and the photography were successful. The "brim" definitely makes the galaxy easily identifiable, helped by the use of a filter to cut down the ambient light pollution. The photo isn't quite as smooth as I liked due to the field rotation inherent in the Alt-Az mount. This prevented me from using an exposure time longer than a minute, and I had to compensate with a high ISO setting.

Telescope: Celestron NexStar 6SE
Device: Sony A5000 (prime focus)
Settings: (1500mm) - ISO 3200 - 60s - (f/10)
Filters: Baader Moon & Skyglow
Time: 2018-04-18 23:08 ~ 2018-04-19 00:48 KST
Location: Naju, Korea
7 photos stacked with DeepSkyStacker 3.3.4

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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