5 research outputs found
Multicolor and multi-spot observations of Starlink's Visorsat
This study provides the results of simultaneous multicolor observations for
the first Visorsat (STARLINK-1436) and the ordinary Starlink satellite,
STARLINK-1113 in the , , , , , , , ,
, , , and bands to quantitatively investigate the extent to
which Visorsat reduces its reflected light. Our results are as follows: (1) in
most cases, Virorsat is fainter than STARLINK-1113, and the sunshade on
Visorsat, therefore, contributes to the reduction of the reflected sunlight;
(2) the magnitude at 550 km altitude (normalized magnitude) of both satellites
often reaches the naked-eye limiting magnitude ( 6.0); (3) from a blackbody
radiation model of the reflected flux, the peak of the reflected components of
both satellites is around the band; and (4) the albedo of the near infrared
range is larger than that of the optical range. Under the assumption that
Visorsat and STARLINK-1113 have the same reflectivity, we estimate the covering
factor, , of the sunshade on Visorsat, using the blackbody radiation
model: the covering factor ranges from . From
the multivariable analysis of the solar phase angle (Sun-target-observer), the
normalized magnitude, and the covering factor, the phase angle versus covering
factor distribution presents a moderate anti-correlation between them,
suggesting that the magnitudes of Visorsat depend not only on the phase angle
but also on the orientation of the sunshade along our line of sight. However,
the impact on astronomical observations from Visorsat-designed satellites
remains serious. Thus, new countermeasures are necessary for the Starlink
satellites to further reduce reflected sunlight.Comment: 31 pages, 9 figures, published in PAS