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Details:
The timelapse photo shows Sirius setting behind the mountains SW of town during morning twilight. In the first subimage every 5th frame of 67 taken is shown, encompassing ~3 minutes; the dark shadows in front are parts of a stone wall. The second subimage zooms in on the first. The last subimage zooms in really tightly to show what happened when Sirius hit the ridgeline: parts of its disk were now behind the ridge, atmospheric dispersion leaving blue as the last color to disappear.
The first 2 subimages have been considerably brightened to make the mountain's edge clearer, while the last one is SOOC (straight out of the camera). In real life I couldn't make out the mountains in the distance, even with a nearly overhead waning gibbous Moon shining on them--it was still too dark in the west, even while the rosy fingers of dawn were encroaching upon the east.
Astro data:
Sirius set:
... actual set time behind mountains: ~6:50:40am MST
... theoretical set time on flat horizon: 6:58:07am MST
... twilights: astro 6:06am, nautical 6:38am, civil 7:10am MST
... sunrise: 7:39am MST
Photo data:
Panasonic G9 in slow-speed burst mode, Lumix 100-300mm lens @ 300mm, tripod
... 67 frames x (f/5.6, 1 sec, ISO 1600) spaced 1/2 sec apart (every 5th frame shown)
... date: Dec 14, 2022 6:48-6:50am MST
Photographer's website:
No URL provided.
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