This short 4K video incorporates time-lapse and still images capturing flaring geostationary satellites. I shot the sequences October 17, 2020.
Twice a year around the equinoxes “geosats” can flare in brightness when they are opposite the Sun and reflect sunlight directly back to the viewer. Normally, geosats are very faint, as they orbit 36,000 km from Earth in an orbit that keeps each one stationary over the same spot on Earth so that fixed satellite dishes can aim at them.
But during flare seasons, geosats can become bright enough to see naked eye and capture with short exposures and wide lenses.
The movie incorporates two sequences:
1. Untracked Camera: With a 20mm lens aimed to the southeast, taking 30-second exposures over 2 hours. The stars trail as the sky turns from east to west, but the geosats remain as a string of fixed dots of light in the sky. The arrows mark the ends of the string.
2. Tracked Camera: With a 50mm lens aimed toward the point in the sky opposite the Sun where the geosats are catching the sunlight. A series of 1-minute exposures taken over 3 hours with the camera tracking the stars shows the geosats as a series of streaks as the camera moves with the stars but the geosats do not.
In both clips the bright object is Mars, then near opposition itself and at its biennial brightest. The video clips cross-fade to still images made from a subset of the time-lapse frames.
While geosats orbit in the equatorial plane of Earth they appear below the Celestial Equator (marked on one of the still images) which is the projection of Earth’s equator onto the sky. This is due to parallax from me observing them from my latitude of 51° north of the equator.
Alas, clouds moved in and prevented more exposures.
Cameras: Untracked - Nikon D750 at ISO 3200; Tracked - Canon 6D MkII at ISO 1600, on a Sky-Watcher Star Adventurer 2i tracker.
Time-lapse frames were processed in Adobe Camera Raw and assembled into 4K movies with TLDF, TimeLapse DeFlicker, using frame blending.
Music by Adi Goldstein / AGSoundtrax.com
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