As can be seen, the crescent is getting quite thin now. Of course, by now it is actually even thinner, see for example http://www.universetoday.com/107663/astro-challenge-nabbing-venus-at-inferior-conjunction/.

Speaking of crescents, there was a New Moon on January 1st and I got some images of the very young Moon on January 2nd. These were all taken with the small Galileoscope to make the entire Moon fit on the camera chip. Here is an image of the crescent itself:

If you look carefully you can discern some details of the lunar surface. I also happened to serendipitously catch an airplane in the act of traversing the image. Here is an animated GIF of the unprocessed frames:

A nice bonus this is. However, my actual goal for the evening was to shoot my first Earthshine image. The “unlit” portion of the Moon is actually faintly illuminated by reflected light from the Earth, and can be made visible using longer exposures:

I’m quite happy with the way this turned out.

Since these appearances were short and variable I did not manage to configure good camera settings and most frames were overexposed. In the end I deliberately used 300 frames taken through lighter clouds and therefore diminished.

This quick image was taken with Galileoscope near sunset, with Venus about 10 degrees above the horizon and piercing through significant cloudiness. Due to bad seeing and general featurelessness of Venus it is unlikely that using the larger scope would have made much of a difference.

I’ll use this opportunity to also post two images taken last month using the Galileoscope: An attempt to capture the ISS by simply following it with the hand-held scope while taking live video …

… and a morning view of the waning gibbous Moon in daylight:

The image was taken around sunset when the sky was still very bright to catch Venus as high as possible, but even so Venus was already very low in the sky (~10° altitude from 52°N). Due to the short exposure times, the sky appears mostly black anyway. Here is an unprocessed sample frame for comparison:

As can be seen, imaging through that much atmosphere severly degrades image quality. Turbulence in the air smears the image, and dispersion (due to wavelength-dependency of refraction) turns objects into little rainbows (in fact, for bright objects the atmosphere can be used as a poor man’s spectograph).

However, stacking multiple of these short exposures averages out some of the distortion, while the rainbow effect can be diminished by aligning all color channels individually. I took about 20,000 frames at 0.5 ms exposure over a period of about 4 minutes, 10,000 of which were used for the image presented here.

Saturn is currently located a little to the upper left of Venus (for Nothern Hemisphere observers). It is certainly not a reasonable time to image Saturn, but it was the logical target after Venus:

Uranus does not have much (atmospheric) surface features to begin with and they will certainly not show in a relatively small scope without special filters. I was hoping to see some of the moons but apparently conditions were not good enough.

A planetary nebula represents the final stage in a smaller stars life cycle, such as our own Sun. Near the end of its life, the star enters a phase of Helium shell burning that causes the star to blow away its outer atmosphere with strong stellar winds, over a period of about 10,000 years. Finally, only the central white dwarf star remains, with no more exciting prospects than to spend the next billion years slowly cooling off.

This is though luck for the star, but the nebula that is formed from the ejected material makes for a pretty picture from afar. The object is still expanding at about 30 km / second. The red color is from hydrogen gas emitting in the H-alpha region. The blue and green in the center should stem from oxygen, although the lack of actual green probably indicates that I need more practice at color-balancing.

Apart from that, however, it is a true color image taken in the visual spectrum. It was composed from 150 individual frames exposed for 10 seconds each, giving a total exposure time of about half an hour. A 0.5 x focal reducer was used.

I am quite happy about the result because I did not have too much luck with faint nebulous objects until now, and the individual frames did not show much appreciable signal before processing. Now that I got it to work in principle I will try going for longer total exposures, that should get rid of the noisiness that is still quite apparent in this image.

Tomorrow, the ISS should make a day-time pass in front of the Moon from here. I’ll try to catch that if I get a chance.

(If you view this on a mobile device you may need to increase the display brightness somewhat to see the fainter detail)

This pass at 4:05 AM over The Hague was not directly overhead, rather, with a maximum altitude of 44°, it provided a more “sideways” view of the station. Also the slower apparent velocity allowed for more relaxed manual tracking, and resulted in more individual frames of the station per pass over the chip.

I originally went out early to image Venus in the hope of at least recognizing the phase, but didn’t get satisfactory results – I accidentally used additive binning which caused Venus to be overexposed in all frames. But I feel these ISS shots adequately compensated my disappointment.

I’ll try Venus another time, although I fear I am generally not in a hopeful position for success with that lady: at latitude 52°N, Venus is already less than 10° above the western horizon at sunset, and over the sea at that.

My main plan for the evening was actually to catch ATV-4 zipping across the Moon as predicted by Heavens Above, but I didn’t even see the space craft. I suspect the prediction was out of date due to all the maneuvering taking place the day before the planned docking.

Well, technically it may have been the third attempt because there were two passes this night and I botched up the first (tracked diligently but forgot to take pictures …).

I track manually while continually acquiring images and try to keep ahead of it in the finder, then let it drift over the chip area. One eye needs to stay glued to the finder while the ISS moves from near the horizon to almost overhead. It is probably the most sportive activity I engage in, as it requires to slowly shift from one yoga-like half-crouch position to the next for several minutes.

Currently ISS is trailed in its orbit by Albert Einstein, the automated transfer vehicle ATV4. It passed about 10 minutes later and I tried to take pictures of it, but as it is much smaller it remained an unimpressive dot.

It seems I turned the sunflower galaxy M63 into a faint blurry something. Also, I think what we see here is only the bright core of the galaxy, maybe about 3 arcminutes in diameter.

Of course, the moons are fainter than the planet so usually the planet will be terribly overexposed when the moons are imaged. At the cost of photometric unscientificness, this can be overcome by merging multiple exposure times in a single image. Here is one of Saturn that shows six of its moons, including faint Hyperion at around 15th magnitude.

And because that is really just a lot of dots without context, here is an annotated version

The process I use is to take a few short exposure frames as for normal planetary images, then one or two longer exposures, then repeat. Each of these frame sets is combined into a meta-frame by some scripting fu that attempts to pull signal from the longer exposures into the dark areas of the shorter exposures. The composite frames can then be stacked as usual. I made a similar one in March for Jupiter

For that one I actually took a gazillion frames over three hours in the hope of making a video out of it once I fully automate the compositing process. Unfortunately I seem to be building up a bit of an image processing backlog. Even now, while I’m trying to reduce the pile, the sky turned clear and the telescope is collecting data outside – argh!

And for the fun of it did one with the Galileoscope as well:

Size is in the objective lens of the beholder.

Yes, I can. Connecting the camera to the Galileoscope was straightforward. Taking an image hand-held is a trifle more challenging, basically the only way to do this is to start recording video and then pointing the tube at the object until you get enough frames that contain the object (of course, this only works for bright objects where exposure times are very short).

However, even with the reduced pixel scale of the Galileoscope my chip was to tiny to fit the image of the full moon. A 0.5x focal reducer was needed, but this turned out to require more inward focus travel than the scope was ready to give willingly. So I had to make do with unwillingly:

I NEVER run out of inward focus travel

The advantage of having a cheap telescope with a flexible plastic tube assembled from a kit becomes apparent: Easy to partially disassemble and bend to your will.

Originally introduced as a $15 telescope for the international year of astronomy 2009, it is now sold at the Galileoscope website itself in packs of six units for $150, i.e. $30 apiece. This seemed to be the most cost-effective solution, even with shipping costs of $140 added on top. The delivery arrived last week so I am now the happy owner of 7 telescopes. Of course, I neglected to consider customs for importing from the United States – another €45 ($60).

Opening the first kit revealed that there was more assembly involved than I had expected: A total of 31 parts form a motoric challenge that needs to be addressed prior to first use. However, assembly requires no tools and the provided instructions were clear enough. In fact, building the scope is an interesting and enjoyable experience, and demonstrates that a refractor really is just an empty tube with bits of glass at the end.

The first completed telescope

I tried the scope on terrestial objects first and later on Saturn. The first thing I noticed is that is really hard to keep anything in the field of view without a mount. And it is next to impossible while focussing the scope, which in turn makes it hard to achieve good focus. It is therefore advisable to practise while it is still light (but well away from the Sun!) when any direction will at least show you something.

The Galileoscope is a 50mm refractor with a focal length of 500mm. Like my Celestron, it is therefore an f/10 scope. A 20 mm eye piece (with plastic lenses but acceptable quality) is provided, this yields 25x magnification and a field of view of about 1.5°. Also provided is a dual use secondary lens that can be configured as a 2 x barlow (yielding 50x at 0.75°) or as a Galilean eyepiece (upright image but almost no field of view). Using the barlow I was just able to make out the rings of Saturn despite the planet erratically jumping through my hand-held field of view.

However, the real feature that makes this little scope more interesting than its cheap department store counterparts is that it comes with a standard 1.25″ barrel. It is therefore possible to connect all the accessories you already have or plan to splurge on. For example, below is the Galileoscope with an 8mm Hyperion wide-field eyepiece. It gives a very usable 60x magnification with a true field of view of about 1.1°. A small drawback is that the barrel does not have a thumbscrew but relies on friction from plastic ridges alone, which does not feel safe for a heavy and expensive eyepiece.

An 8mm Hyperion wide-field eyepiece all but outweighs the actual telescope, giving the setup the characteristics of a cudgel (the price imbalance is probably even greater)

Speaking of field of view, this is usually given as 1.5° for the Galileoscope. However, that is simply the value achieved with the standard eye piece and not a limitation of the telescope. A 40mm Ploessl yields a 3° FOV at 12x magnification. For the fun of it I tried adding a 0.5 focal reducer. At this point a limitation at about 5° became apparent but this is to be expected from the limited size of the pupil (minimum usable magnification). It would be interesting to connect a large chip camera at prime focus to determine the limiting FOV.

However, what I have is a very small chip Flea3 camera and at this point I’m just itching to try the scope with it. At first it may seem silly to make photos with a cheap 50mm scope when you have a 200mm (8″) scope, but actually there can be benefits

• 4 x larger field of view even for the tiny chip, possibly just enough for full moon
• For extended objects, light intensity per pixel is not reduced compared to a larger scope (both are f/10). In fact it might be slighlty better as the refractor does not have the obstruction of the secondary mirror
• The reduced pixel scale allows for longer unguided exposures

However, this will have to wait until I manage to connect the scope onto my Celestron. A Celestron piggy-back camera adapter is already on its way, if this is successful I will most certainly post the results here – watch this space!

Although this was the main motivation for creating the blog and the gallery in the first place, I have other interests related to image processing, computer graphics, and software development, and may also write on these things (or off-topic rants). This is my first attempt at blogging so I myself am curious to see how this will develop.

For the last 7 years, I maintained www.chrfr.de as a purist static HTML site, without PHP and using only Notepad as editor and a command line ftp client. However, the large overhead to write and publish proved to be restrictive, so the content was both limited and frequently outdated. I hope this WordPress-based blog and gallery reduces the hurdle to publish images and thoughts on a timely basis.

Clear Skies!