Cees BassaHappy new year! Another year means another year-long keogram! Every 15 seconds throughout 2022, my trusty all-sky camera took a picture of the sky above the Netherlands. Combining these 2.1 million images into a year-long keogram reveals this picture, which shows the length of the night change throughout the year (the hourglass shape), when the Moon was visible at night (diagonal bands), and the Sun higher in the sky during summer, as well as lots and lots of clouds passing overhead.
This is the second year that this all-sky camera, consisting of a @Raspberry_Pi computer and a ZWO CMOS camera, ran continuously for a year. Compare the 2022 year-long keogram with that of 2021.
The hourglass shape hardly changes, but the diagonal bands are shifted, as the full Moons occur on different days. The cloud patterns are obviously also different, though generally winter has worse weather (more clouds) than summer.
Zooming in on the months of June and December show more clearly when it is cloudy and when the sky is clear. These images run from midnight to midnight in the UTC timezone, Also note the bright orange sky during the last hour of the last day in December -- fireworks in the Netherlands at 23:00UTC!
Sven@cgbassa I'm curious about the processing in those. Is the camera running with the same settings always, or does it adjust (which I'd assume, to get more detail at night) and the post-processing corrects for that?
@HeNeArXn The camera can be controlled by exposure time and gain. I've implemented the logic such that it will use 15 seconds exposures at night at maximum gain, and during twilight will lower the gain until zero, after which the exposure time is lowered. This to maximize the night time exposure time. So no post processing artifacts instead of exposure steps during daytime.
@cgbassa based on time relative to sundown? Otherwise adjusting the exposure would "correct" out the differences you are trying to show in this plot, right?