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Basically a repeat of Is Starlink 1130 (Darksat) really dimmer? but this time with Visorsat.

What is the observed brightness of VisorSat(s) and is it dimmer than non-Visorsat Starlink satellites?

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Intial observations of the prototype Visorsat with an orbital altitude of ~482km puts it's maximum brightness at magnitude 7. When compared to a normal Starlink satellite with a magnitude of 4.4, this represents at minimum a decrease in brightness by a factor of 10.

However with the recent set of Visorsats from L9 reaching operational altitude at 550km, a larger set of data was collected about the Visorsat brightness. It was found that they had an average brightness of around 6.0 magnitude, which was brighter than initial observations suggested. This is still however dimmer than the 4.63 magnitude for regular Starlink satellites. Notably however, there were still Visorsats with brightnesses reaching magnitude 3.

Further observations showed a standard magnitude (satellite at 1000km) average of 7.98, which results in a dimming of;

The averages for both these data sets are about two magnitudes fainter than that of pre-VisorSat Starlink birds

This combined with other observations (1 and 2) indicates that Visorsat is ~1.6 to 2 magnitudes dimmer than Starlink.

Large Observation Set 1

Large Observation Set 2

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Initial Observation 1

The Starlink satellite 'Visorsat' (spacetrack #45713) was not seen on 2020 August 6 at 01:21:00 UTC. A star of magnitude 6.7 was clearly observed in the field of view so the limiting magnitude was around 7. The observation was made with 15 x 50 binoculars under slightly hazy skies.

The satellite altitude was 482 km and its range was 502 km. According to the paper linked below, a regular Starlink satellite at that distance would be approximately magnitude 4.4. So, confirmation of this preliminary result would imply that Visorsat is, at most, only about 10% as bright as a regular Starlink satellite.

https://arxiv.org/abs/2006.08422

Has anyone else observed Visorsat?

Initial Observation 2

First observation by me of Visorsat in 550km operational orbit on 2020-08-17. Site 50.14N 5.43W. Sun depression angle 13deg.

All observations azimuth 330-340, elevation 60-70deg.
Starlink - mag
1413 - 4.9
1419 - ~5.5
1422 - 5.3
1436 (Visorsat) - 7.0 21:07UTC
1399 - 4.8
1393 - 4.8
1394 - 4.8

All objects in same plane of L1.7 launch.

So Visorsat is ~2 magnitudes fainter than other objects in same plane. Darksat was mag6, ~1 magnitude fainter than other objects in same plane.

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  • $\begingroup$ "Initial observation" suggests a positive identification of the satellite. That's maybe too strong to describe that message which boils down to we didn't see it but should have been able to see objects as faint as magnitude 7. $\endgroup$ – user2705196 Aug 10 at 13:07
  • $\begingroup$ I can't +1 again for all the extra effort. You might consider asking a separate question about the part that seems "Confusing AHAHSAGDH" :-) $\endgroup$ – uhoh Sep 7 at 13:10

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