Wesley's Tool-Box

This morning, not long after midnight, I gazed the southern sky to find the planets Saturn and Mars near the full Moon. These planets were both near their oppositions - it was just 11 days away for Saturn and Mars went through it less than 6 hours ago. You don't see their oppositions happening close together often because Mars opposition happens every 25 to 26 months, while it's around 12 months and 2 weeks for Saturn. The next time the two occurring within two weeks of each other is in 2082, when it's 4 days apart (Saturn: August 29, Mars: September 2).

I attached my iPhone 6S Plus onto the Celestron X-Cel LX 9mm eyepiece that I bought relatively recently to observe the planets in more detail. It was the first time both were used on the telescope for astrophotography. They both worked as expected and produced the images you see above. The brightness of the Moon nearby may have washed out a bit of detail, but other than that it turned out fine. I may have to try out using filters next time to see if it makes any difference.

Telescope: Celestron NexStar 6SE + X-Cel LX 9mm eyepiece
Device: iPhone 6S Plus (afocal)
Filters: None
Location: Naju, Korea
Stacked with PIPP 2.5.5 and RegiStax 6.1.0.8

Saturn
Settings: 29mm - ISO 125 - 1/20s - f/2.2
Time: 2016-05-23 01:58 KST
31 photos

Mars
Settings: 29mm - ISO 32 - 1/90s - f/2.2
Time: 2016-05-23 02:04 KST
100 photos

In the early evening these days, Saturn is seen shining brightly in the southwestern sky. The apartments nearby hinder the sight well before it sets into the western horizon, though. And in a few weeks, even this narrow opportunity would go away. This meant that now was the time to take photos of Saturn with my new A5000.

Preliminary attempts last week were disappointing, however. The planet looked dark and fuzzy. After analyzing the problem, I concluded that the rails on the window and the pollution (atmospheric and light-induced) near the horizon were causing this. So I raised the telescope up a bit and tried to shoot as early in the evening as possible.

As a result, the photographs from last evening came out looking good. Cassini division and the differently-coloured layers of the surface are all visible. This is comparable to the ones I took back in May, even though the apparent size is smaller (18.32 vs. 15.85 arc seconds). This may have been helped by A5000 having a slightly higher resolving power (0.19 vs. 0.20 arc seconds / pixel) than iPhone 6 Plus.

This is encouraging in a couple of ways. This confirmed A5000's ability to provide almost all my astrophotography needs. And on May 2016, Mars will be about as big as Saturn today (excluding the ring part), so I may be able to get some nice photos of the red planet.

Telescope: Celestron NexStar 6SE + 2.5x barlow
Device: Sony A5000 (prime focus)
Settings: (3750mm) - ISO 800 - 1/4s - (f/25)
Filters: None
Time: 2015-09-22 19:35 - 19:44 KST
Location: Naju, Korea
33 photos stacked with RegiStax 6.1.0.8

As Pluto moved toward the western horizon, a planet started to come into the telescope's view through the southern window - Neptune. It was the first time I had seen it in person, but seeing as how relatively dim it is compared to other planets (magnitude 7.8), I decided to take photos the same way I do for stars.

Sure enough, it was caught on the photos as a moving bright spot, next to a 6.9-magnitude star called HD 214686. But I soon discovered that it wasn't the only object moving. A faint dot of about magnitude 13 was moving considerably faster than Neptune. Given the brightness, it had to be a small but known celestial object.

Consulting the minor planet database revealed the object to be 303 Josephina, an asteroid from the main belt with a diameter of about 100km. Out of pure coincidence, I had caught a planet and an asteroid together on several photos.


But the surprise didn't end there for me. I noticed that Neptune either had a bump or a small dot next to it. It turned out that it was Triton, by far the largest satellite of Neptune with apparent brightness of magnitude 13.5. Photographs taken a day apart clearly shows its changing position relative to the planet, as well. So thanks to the long exposure photography, I was able to take a planet, a satellite, and an asteroid all at once.

Here's the full version of the final frame of the animation, if you want to see it.

Telescope: Celestron NexStar 6SE
Device: Sony A5000 (prime focus)
Settings: (1500mm) - (f/10)
Filters: None
Location: Naju, Korea

#1: ISO 800 - 20s - 2015-09-10 00:14 KST
#2: ISO 800 - 20s - 2015-09-10 01:12 KST
#3: ISO 800 - 20s - 2015-09-10 02:34 KST
#4: ISO 1000 - 30s - 2015-09-10 23:28 - 23:30 KST (3 photos stacked)
#4: ISO 1000 - 30s - 2015-09-11 00:32 - 00:37 KST (2 photos stacked)

One of the main reasons I decided to buy a new camera was that it would yield a lower-noise photo at high ISO settings, making it better for long-exposure astrophotography. To confirm this, one of the first objects I chose to take photos of was the dwarf planet Pluto.

It moved a little to the east since the last time, already past the ξ2(Xi 2) Sagittarii and not near a particularly bright star. The brightest stars in the animated frames above are only about magnitude 11. Nevertheless, Pluto was discernible when comparing the two frames taken a day apart under a bright monitor. Dimmest stars visible reached magnitude 15, and Pluto itself moved clearly enough to see that it's not a background star.

If you feel particularly bored, you can try picking it out of the full version of the September 10 photo.

Telescope: Celestron NexStar 6SE
Device: Sony A5000 (prime focus)
Settings: (1500mm) - (f/10)
Filters: None
Location: Naju, Korea

#1: ISO 800 - 20s - 2015-09-09 22:09 KST
#2: ISO 1000 - 30s - 2015-09-10 21:44 KST

For the past few weeks, clouds and rain due to the monsoon prevented me from seeing a clear sky at night. But that period is nearing its end, and last night I had a near-perfect opportunity - no clouds and no haze. Brightness of the first-quarter Moon was about the only fly in the ointment.

As I was only able to observe the southern sky out the window of my room, I consulted a star chart to see if anything interesting was there to see. Pluto immediately caught my eyes. As you might know, this dwarf planet is making headlines at the time of this writing because the New Horizons probe made a flyby two weeks ago. The unprecedented details of the images from the probe is capturing public interest, and mine. So I wondered if I could see a glimpse of it with my own telescope.

Problem is, Pluto is very faint - 14.1-magnitude right now. Based on my past observations, it would be at or just outside my limits even with astrophotography. Sure enough, when I pointed my telescope to the right position, I couldn't make it out visually. So I attached my DSLR camera and took several long-exposure photos in hoping that they'd be more revealing. One of such result is the photo you see above. The brightest star is ξ1(Xi 1) Sagittarii, a 5.1-magnitude star. Most of the rest are fainter than 10-magnitude.


After carefully comparing the photo with a detailed star chart, I finally found a dot that didn't belong to a star. This seemed to be Pluto that I was looking for. But to make sure, I compared all the photos I took over the span of about an hour and looked to see if there was any movement - a telltale sign that it's not a star, but an object moving around the solar system.


Indeed there was. This was the dwarf planet I was looking for. This process of comparison was basically how Pluto was identified and discovered in the first place back in 1930, so it was pretty satisfying to retrace the steps. I'm also glad to know that the southern sky at Naju is still dark enough to see this faraway world.

Telescope: Celestron NexStar 6SE
Device: Canon EOS 450D (prime focus)
Settings: (1500mm) - ISO 1600 - 30s - (f/10)
Filters: None
Time: 2015-07-26 00:06 - 01:13 KST
Location: Naju, Korea