Saturday, July 15, 2017

International Space Station

If you are in the right place at the right time you might be able to catch a glimpse of the International Space Station (ISS) as it passes in front of the Sun or Moon. These types of events are called "transits" and are fairly uncommon.

Transits are hard to see and easy to miss. The ISS orbits between 205 and 255 miles above the surface of the Earth, and moves at over 17,000 miles per hour. At that distance and speed, lunar and solar transits only last about one second or less and are only visible from a relatively narrow strip of land on the Earth's surface.

But finding a good viewing spot and time is relatively easy with ISS Transit Finder. This site lets you specify an area and a date range, and will calculate when and where the ISS will pass in front of the Sun or Moon.

A solar transit occurred on July 14, 2017. The center of the centerline of the transit was located in Lake Raven in Huntsville State Park, which is not far from where I live. I set up the ShortTube 80 with a full-aperture glass solar filter along the shore of the lake, and caught the transit using the Mallincam SkyRaider camera. Here is a composite image of the transit:

International Space Station transit of the Sun, July 14, 2017. Sunspot group AR2665 is located on the right.

The frame rate of the camera was not consistent, which is why there are gaps in the image sequence. The original monochrome images have been colorized to approximate the view through the solar filter.

The following video shows the transit in fairly close to real-time. Note that there are TWO transits! The first is probably an insect that either flew in front of the telescope or crawled across the objective lens.

On a side note, one of the lessons that I learned from the Venus Transit was that good polar alignment is critical for good results. This is difficult to do in the daytime, though, unless the mount has some kind of "magic" hardware and software for figuring out its exact position. My '80s-tech Vixen Super Polaris EQ mount does not have any fancy alignment features, but I was able to get a decent polar alignment using my mobile phone.

I plan on trying to image more ISS transits in the future when the opportunities arise. I would really like to get a lunar transit now.

Sunday, July 2, 2017

Mallincam SkyRaider

I just acquired a (almost never) used monochrome Mallincam SkyRaider Autoguider. And since the skies magically cleared shortly after the previous owner and I made the exchange, we decided to hook it up to one of my scopes and try some lunar imaging.

The results, in my opinion, were fantastic!

Moon, July 1, 2017; Mallincam SkyRaider w/Baader Contrast Booster; ST80 on Vixen SP
Click here for full-size image
98 images were stacked in RegiStax 5.1, with wavelet sharpening applied. The sharpness and contrast are better than any other image of the moon that I've taken previously, I think.

The camera can also do long exposures, but the images are very noisy.  The included software has a "dark field" feature that removes a lot of the noise, but the number of hot pixels on the sensor make it impractical for imaging deep sky objects.  Here is a single frame of Messier 4, with a bonus airplane thrown in just for fun:

Messier 4; Mallincam SkyRaider w/Baader Contrast Booster; ST80 on Vixen SP. This is a single 2-minute exposure with a dark frame applied.
Next, I want to try solar imaging with the ST80 and the glass solar filter. If that works out well, then I plan on using that combo for imaging the August 21, 2017 solar eclipse.

Stay tuned!

Friday, February 3, 2017

I'm still alive

It's been a long time since I've made any kind of serious attempt at imaging. The weather has been horrible since...well, it seems like forever now. And even when it has been good I've not been able to get out with the telescope for one reason or another.

Well, the forces of nature, time, and fortune came together the other day and I dragged everything out to the ObservaRory and captured a few images.

My primary mission was to test some new software and a tablet for controlling the camera.

The goal was to see if it was practical to reduce the amount of equipment taken into the field. Overall it was a success.

First, the images:

Messier 45, the PleiadesST80 w/Baader CB on Vixen SP; Canon EOS Rebel T3; 15x360

Caldwell 49, the Rosette NebulaST80 w/Baader CB on Vixen SP; Canon EOS Rebel T3; 17x360
Now on to the technical details.

The tablet was a Samsung Galaxy Tab E, and the software was DSLR Controller. DSLR Controller is similar to Canon's EOS Utility in that it provides nearly total control over the camera. It is not as feature-rich as Backyard EOS (which is specifically designed for astroimaging), but it has the advantage of working on Android tablets and phones. DSLR Controller supports a wide variety of Canon cameras.

In short, I like the combination of the tablet and DSLR Controller. The software was easy to use once I got the hang of how to set up a time lapse session. Focusing and centering the targets was made much easier by being able to hold the tablet while adjusting the scope. Making adjustments while using the laptop has always been difficult for me because the laptop is mostly confined to sitting on a table.

Once I got the imaging sequences set up and running the whole process was fairly painless. However, the software did crash on me a few times while I was setting up. I have not yet been able to ascertain the cause.

The software also left the camera display on, despite the fact that I turned it off on the camera's control panel. Between that and the live view mode that DSLR Controller uses by default, the camera battery ran out much sooner than usual. When I get a chance I will see if there are options to turn these features off.

I wasn't able to take any darks or flats for the images above due to the battery issue. But other than that I'm mostly happy with the results. I'm glad to have finally gotten a chance to do some imaging again. Hopefully there will be more opportunities in the near future.

Wednesday, August 17, 2016

2016 Perseids

Clouds here at the ObservaRory spoiled much of the show during the 2016 Perseids. I set up the camera sometime after midnight and had it take 30-second exposures until the battery ran out. Despite the clouds, though, it caught images of several meteors, as well as a few other sky fairies.

The image below is my favorite. It was taken sometime near the end of the run. A thin layer of clouds covers much of the sky. The Pleiades is on the right, and Capella--appearing large and fuzzy due to refraction caused by the clouds--is at center bottom. The tree in the lower-right appears blurred because of the wind.

This little meteor originated below and left of the Double Cluster in Perseus.

One of the streaks in this image is a meteor, but the other is a satellite. Guess which one! (Answer below.)

While both appear to be good candidates for Perseids (they seem to originate from the same radiant), the lower streak is actually a satellite. Bright meteors show up in images as multi-colored streaks. They also only appear in one image because they move across the sky so quickly.

Satellites, on the other hand, are usually white and move slowly, often appearing in two or more images.

The animate GIF below is composed of two frames that were taken during a satellite flare, possibly from an Iridium satellite. The fuzzy object at the top is the Andromeda Galaxy. The frames are aligned on the object. Each frame is 30 seconds long, with a 5-second gap between. The motion of the background stars represents the rotation of Earth during the 65-second period.

A flare, possibly from an Iridium satellite.

Saturday, August 6, 2016

Milky Way on a Country Road

There is a region north of Huntsville, Texas where the sky is considerably darker than most of East Texas. It measures from a low to a high 3 on the Bortle scale, and is roughly located between the Old Spanish Road (OSR) to the south, Palestine to the north, Interstate 45 on the west, and Lufkin on the east. A portion of it is south of the OSR, not far from my house.

My son and I drove through part of this area last February doing a light pollution survey. I was really impressed with how the sky looked there, and decided to revisit it during the summer. So, the other day we drove out to a spot on the side of a road somewhere between Weldon and Lovelady, about 30 minutes from our house. The view was spectacular!

The Milky Way stood out with very high contrast compared to how it appears at the ObservaRory. It's not quite X Bar Ranch dark there, but it is still very good. Below is a composite image of photos that I took with the DSLR and a zoom lens.

Milky Way, Canon EOS Rebel T3, EFS 18-55mm lens @ 18mm (f/3.5), 6x30 @ ISO-3200, stacked in DeepSkyStacker, color-corrected in Photoshop CS6
Below is an enhanced version that brings out the stars and dust lanes:

Same image as above, enhanced using the Detail Extractor in the Color Efex Pro 4 filter collection, which is part of the Google Nik Collection of filters in Photoshop.

Monday, August 1, 2016

Back Yard Astronomy

The right combination of time, energy, and weather conditions still elude me lately. I haven't done much more than peek out the window at the stars now and then. That gave me an idea, however.

Last night I set up the trusty DSLR at one of the back windows and started making a time-lapse of the sky.

But I didn't account for last night's high humidity. The window fogged up shortly after the sequence was started, and I didn't discover the problem until the morning. There weren't enough frames to make a decent time lapse.

Still, there were a few pictures that I thought were pretty.

Below, the constellation Scorpius, containing the bright red star Antares, dominates the center of the image. Mars and Saturn are visible in the upper-right. Ptolemy's Cluster and the Teapot asterism are on the left. There are clouds, mostly above the treeline, to the right. The Milky Way is visible at the top, just to the left of center. The image at the end of the post has labels.

To the ancient Greeks, the star Antares appeared similar in color and brightness to Mars, which they called Ares. The name Antares means, "rival to Ares" or "equal to Ares." Mars is approaching Antares in the sky, and the two will be less than 2 degrees apart, forming a nearly straight line with Saturn, on August 24, 2016.

Single, 30-second exposure at ISO-1600 made with a Canon EOS Rebel T5 with the stock EFS 18-55mm zoom lens @ 18mm. Corrected for lens distortion and color balanced in Photoshop CS6. Noise reduction using Google Nik Collection Dfine 2.0 Photoshop plug-in.

Saturday, May 14, 2016

2016 Mercury Transit

The Mercury transit...

Well, I almost missed it. Most of Texas (and the United States, for that matter) was socked in with clouds. The few places that were clear were too far for me to travel.

But amateur astronomers almost always hold on to at least a little bit of hope, even when the odds are overwhelmingly against us. We patiently scan the sky for "sucker holes" and engage in our preferred ritual superstitions to drive away the clouds. (Yeah, I know, we're supposed to be scientific and all that...but desperate circumstances often lead to desperate actions.)

The sky DID clear up for a few minutes--at least enough for me to focus and get a few shots in. It's nothing spectacular, but here it is:

Click here for the full-size version.

Mercury is the dot to the upper-right of center. The big sunspot group to the left is AR2542. Other smaller sunspot groups are also visible.

This is a stack of four exposures, each 1/2000th of second at ISO-100, taken with a Canon T3 on my Orion ShortTube 80. I used an Orion full-aperture solar filter, and the Baader Contrast Booster (to reduce chromatic aberration). The images were stacked and wavelet sharpened in RegiStax5. I did an "auto color" correction in Photoshop CS6 to brighten the image a bit.

Click here to see my images of the 2012 Venus transit.