Telescopically imaging the ISS (plus some deep-sky)

So far, my satellite imaging has always been done with a DSLR and normal camera lenses and were essentially 'wide field'. The largest focal length I so far used was 180 mm.

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Last week I have experimented with telescopic imaging of the International Space Station (ISS), using my Celestron C6 (15 cm F/10 Schmidt-Cassegrain). Above is the best image, shot 6 June 2014 at 22:07:13 UT as the ISS was zipping past beta Bootes. It is a single image from the series, taken at 1/4000th second at ISO 800.

I kept it simple: I did not actively track the ISS, but looked for points where it passed close to a reasonably bright star, and then pointed the telescope to that position. As the ISS passed that point, I did a rapid burst series of images, a few of them which then showed the ISS zipping through the field. I used 1/4000th second exposures.

That technique is actually enough to get some decent pictures. Later, I will probably experiment with active tracking using computer guidance of the mount, and see whether video might yield more that photography (one drawback of video is a lower resolution, so a need to work with Barlows).

Having the telescope out anyway, I made some deep-sky images too the last two nights, of some bright summer sky icons. Again, I kept it simple. As I work from a town center, and a location where I cannot see the Pole star due to obstruction by a building (which hampers telescope alignment), I kept exposure times short, to 10-15 seconds. Then I stacked large numbers of images.

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The above image of M27, the Dumbbell nebula, a planetary nebula in Vulpecula, is my favourite. It is a stack of 57 images of 15 seconds exposure each at 2000 ISO. The faintest stars on this image are near mag. +16.8, which is not bad with short exposures from a town center.

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Another iconic planetary nebula in the summer sky is M57, the Ring nebula in Lyra. The image is on the same scale as that of M27 above. This image is the result of stacking 60 images of 10 seconds exposure (the scope didn't track that well that night) at 1600 ISO.

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The final image shows globular cluster M13 in Hercules. It is a stack of 57 images of 15 seconds exposure, taken at 2000 ISO.

OT - a new telescope and imaging the moon

Since 18 November I have done little in terms of satellite observing, for reasons outlined below. Therefore, a post that is slightly OT - but still astronomical in topic.

Generally bad weather over the past two months - lots of clouds, and even snow mid January - is one primary reason for my inactivity on the satellite observing front. Another is that mid-winter isn't the best period of the year at 52 N due to the "winter blackout" of many objects in LEO. Third, I am occupied these months by a few other things, including the "Super Secret Project" which I obviously can't talk about yet (but is very exciting).

The generally bad weather over December and January meant that I could not yet fully use my new toy. Near the start of December, I obtained myself a new telescope, partly with the proceeds of the Van der Bilt Prize. The telescope is a Celestron C6 Schmidt-Cassegrain (15 cm f=1500) on an SGT Advanced Goto equatorial mount. Here is me showing it off:

For quite a while I wanted a slightly bigger and optically better telescope than the simple Meade ETX-70 and small and very old 4.5" Newton I already had, yet found it just too expensive. The extra money from the Van der Bilt Prize meant it became just feasible for me to finally buy something better.

Since I have no option for a permanent setup and live small, it could not be a very large and heavy setup, so I choose this 6" Schmidt-Cassegrain (the mount is heavier than I expected though). Even though I have not been able to use it extensively yet, I so far like it very much!

Twice in January I could test it out on the moon. Here are some images shot on January 22nd. First, an old-fashioned single shot photograph of the moon disc (C6 prime focus with F6.3 flattener/reducer, and Canon EOS 60D, 1/160s at ISO 200). Seeing was quite mediocre, the air was not quite steady (the image was "wavy" as if reflected on the surface of water):

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I also used the HD movie capabilities of my Canon EOS 60D to shoot a few short movies, and then stack frames from these movies using Registax. This results in a dramatic increase in detail. The images below are each the result of stacking 200 movie frames, selected out of movie sequences of ~550 frames each, and are my first ever experiments with Registax (which is quite complex to use for a novice):

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Southern highlands: Clavius and Tycho

Northern part of Mare Imbrium with Sinus Iridium,

Plato and Vallis Alpes

Mare Humorum, Mare Nubium, with Gassendi

and Bullialdus

One of the intended primary goals for this telescope will be to observe asteroid occultations, with the WATEC 902H video camera plus GPS time inserter attached to it.Satellites are not the primary goal of this new instrument.