Wesley's Tool-Box

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

My Canon EOS 450D DSLR camera is a fine equipment, but it is showing its age. So I decided to invest in a new equipment but not at too much expense. After much comparing, I decided to go with A5000, an entry-level mirrorless camera from Sony. It's got a highly sensitive sensor for its class, yet it's currently selling at quite a discount - about US$280 with a 16-50mm bundled lens, or just under US$200 for the main body.

As I ordered this camera, I also bought a T-ring for its E-mount lens mount so I could install it on my Celestron telescope. What you see above is how the camera looks with this attachment. I only took a handful of photos with the bundled lens before replacing it with the T-ring to start photographing the stars. I'm keeping the lens around just in case I need to shoot regular photos.


And this is how my new astrophotography setup looks like. The camera is practically the lightest APS-C sensor-based mirrorless camera out there, so it hardly burdens the telescope. I can also use my smartphone to remotely control the camera - a convenient feature that also prevents shaky images. I'm hoping to get some nice photographs out of this, so stay tuned.

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

On the Memorial Day in Korea earlier this month, the night sky was clear and had three planets shining brightly in the sky at the same time. I took my astrophotography equipment outside and got some burst mode photos of the planets.

It seemed that Venus was quite bright and the default camera app didn't have enough adjustments available to make it dark enough to reveal any details on the half-disc. Also, Jupiter now being in the lower altitude hampered the details somewhat. Other than that, things turned out fine. It was nice to have a direct comparison of the apparent sizes between the planets.

Telescope: Celestron NexStar 6SE + 5mm eyepiece
Device: iPhone 6 Plus (afocal)
Filters: None
Location: Naju, Korea
Stacked with RegiStax 6.1.0.8

Saturn
Settings: 29mm - ISO 400 - 1/15s - f/2.2
Time: 2015-06-06 21:44 KST
30 photos

Venus
Settings: 29mm - ISO 250 - 1/30s - f/2.2
Time: 2015-06-06 21:40 KST
100 photos

Jupiter
Settings: 29mm - ISO 320 - 1/30s - f/2.2
Time: 2015-06-06 21:16 KST
100 photos