Antu
11-03-2013, 12:40 PM
Hi All,
Sorry for being absent for a long time, too many things to do as usual. But yesterday I came across a quite impressive phenomenon. Well, we astrophotographers know very well how difficult sometimes to correct color gradients on our images. If the FOV of your telescope is small enough then it's much easier to do, however for really wide field instruments such postprocessing might become a hell. What is the cause of those color gradients ? For the answer, please have a look at the image I took yesterday at Las Campanas in Atacama desert:
http://spaceweather.com/gallery/full_image.php?image_name=Yuri-Beletsky-airglow_campanas_1362937190.jpg
Yes, this is atmospheric "airglow". Last night it was particularly strong. The airglow is the light of electronically and/or vibration-rotationally excited atoms and molecules 80 km or higher. The red color is due to OH radicals emission (and possibly atomic oxygen emission too). Unlike aurorae, which are visible in high latitudes only, airglow can be observable from anywhere on the planet. Basically, it does not depend on the latitude. Therefore, all of us are equally affected - regardless whether you are observing in Australia, Europe, or Chilean desert. Sigh ...
A low-resolution image is attached but the best would be to look at higher resolution (see the link above)
I used Canon 5D Mark II and Nikkor 14-24 f/2.8 lens.
Clear sky !
Sorry for being absent for a long time, too many things to do as usual. But yesterday I came across a quite impressive phenomenon. Well, we astrophotographers know very well how difficult sometimes to correct color gradients on our images. If the FOV of your telescope is small enough then it's much easier to do, however for really wide field instruments such postprocessing might become a hell. What is the cause of those color gradients ? For the answer, please have a look at the image I took yesterday at Las Campanas in Atacama desert:
http://spaceweather.com/gallery/full_image.php?image_name=Yuri-Beletsky-airglow_campanas_1362937190.jpg
Yes, this is atmospheric "airglow". Last night it was particularly strong. The airglow is the light of electronically and/or vibration-rotationally excited atoms and molecules 80 km or higher. The red color is due to OH radicals emission (and possibly atomic oxygen emission too). Unlike aurorae, which are visible in high latitudes only, airglow can be observable from anywhere on the planet. Basically, it does not depend on the latitude. Therefore, all of us are equally affected - regardless whether you are observing in Australia, Europe, or Chilean desert. Sigh ...
A low-resolution image is attached but the best would be to look at higher resolution (see the link above)
I used Canon 5D Mark II and Nikkor 14-24 f/2.8 lens.
Clear sky !