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Tuesday, February 22, 2011

Orion sinks in the light pollution

One hundred kilometers from the place where I live, there is a future-proof project against light pollution called "Sternepark Schwäbische Alb". Now I am certainly sure why it exists. The reason is clearly visible even on my ... camera display!
In fact, I wanted to show you the southern sky from my site in this post. After several short shots with a Nikon d3100 digital camera I noticed that the light pollution in my site leads to terrible results, i.e. strong gradients. Unfortunately, non-celestial light sources gave my photos a terrible orange tone/gradient at night.
I tried to correct the gradients in photoshop with a technique I described here and I produced the cropped photo above. My light-pollution-removal technics on my computer are even more complex than that and I showed them in my recipes :-) =>Remove gradients caused by non-celestial light sources and remove remained light pollution and =>One shot color astrophotography using Aperture (Mac). Let's go back to the photo. Remember this is only one 20 seconds shot at f/3.5 and ISO 1600 without any LPS filter on a green Vixen GP mount. It shows the Orion constellation in the southern sky as seen from my observatory in Stuttgart. My new Nikon d3100 with its standard 18-55mm lense had its first light at that night. However for me, the heavy light pollution makes a Hutech IDAS LPS P2 filter inevitable from now on to continue with DSLR astrophotography. The processed version of the entire photo available here (5 MB) looks much better than the unprocessed one but we are agreed ... photo processing can not replace a dark sky!

The light pollution gets worse by the time here in Europe. Most of the politicians are not seriously interested to solve this problem. Since there is still no law against light pollution in the European Union*, european astronomers must cover long distances with their telescope equipment, i.e. to drive far away from the light polluted european cities in order to find the last dark sites where they can practice astronomy.
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Watch a film about light pollution at: http://youtu.be
Please visit: http://www.darksky.org
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* except Slovenia. This modern european country recognizes the great value of the dark sky and protects it also by law.


Monday, February 14, 2011

Autoguiding through the clouds

Unfortunately, in the last three nights the weather in South Germany was unsuitable for astrophotography. The atmospharic conditions and the seeing were bad. The moon light also produced strong gradients in the photos. However, even through the cirrostratus clouds, it was possible to test in some way my autoguiding system now consisting of an old SBIG ST7 on my small FS-60C telescope.
The spiral galaxy on the screen is the M101 in Ursa Major, captured in a 2 minutes exposure at 365mm FL (f/6). The peaks of the guiding curve are evidence of the bad seeing at that night.
Watch the autoguiding in action!
These are the autoguiding parameters used. They seem to work pretty well but I think, it is reasonable to repeat the autoguiding test under better weather conditions in the future.
The galaxy pair shown above is the M51 with its companion NGC5195 in the constellation of Ursa Major. This unguided photo has been literally shot through the clouds (!) with my 21cm cassegrain telescope at f/11.5 and the ST7XME in only 2x3 minutes.

Wednesday, February 02, 2011