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2009 Noctilucent Cloud Season

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Author Topic: 2009 Noctilucent Cloud Season  (Read 15804 times)
Martin Mc Kenna
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Maghera, N. Ireland

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« Reply #165 on: June 19, 2009, 04:21:58 pm »

Thanks very much Brian and Richard.

Richard, camera's can enhance the brightness, but only if you overexpose the image. Those images from last night match what I seen from here, I always try my best to record the image as seen visually, this what I have been doing with all NLC images this season. The difficult part is the motion, NLCs will drift slightly even during a short exposure often blurring/trailing on the image. High ISO and short shutters reduce this effect, since my camera is noisy I use a low ISO and a slightly longer shutter. Those were taken using ISO200 last night which shows how bright the NLCs were, any higher and the image would have been burn't out. With the naked eye they cast shadows, illuminated the fields in the country, and reflected their multi colours off patches of ordinary cloud in the sky which was amazing. As John 9929 has done in the past - you can read a newspaper at night due to their brilliance. A type 5 display will get the attention of anyone who even glances out the window at the sky.

As for the stars, the brightest stars may be faintly seen through a bright type 4 display, however a type 5 show, like last night's, and the night before, will wash even the brightest stars from the sky. I would estimate that the recent displays were similar to the mag of planet Venus, if not much brighter, the same thing was seen during the 2008 season also when Venus was blocked out by NLC. So, in a nut shell, they are extremely bright!. Images don't enhance the mag in my opinion onless they are overexposed. They have got to be the most difficult subject to shoot. Bright twilight is with us for much of the short nights here, however during the middle of the night the twilight darkens further which is the best time to see NLCs, in my opinion,because  the colours and brightness jump out from the sky, and the more oblique viewing angle presents wonderful structures.

As for the display last night, the camera picked up the white and blue colours but missed out on the lovely yellow, green, and gold tones.
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