Multicolor and multi-spot observations of Starlink’s Visorsat

This study provides the results of simultaneous multicolor observations for first Visorsat (STARLINK-1436) and ordinary Starlink satellite, STARLINK-1113 in $U$, $B$, $V$, $g'$, $r$, $i$, $R_{\rm C}$, $I_{\rm $z$, $J$, $H$, $K_s$ bands to quantitatively investigate extent which reduces its reflected light. Our are as follows: (1) most cases, Virorsat is fainter than STARLINK-1113, sunshade on Visorsat, therefore, contributes reduction sunlight; (2) magnitude at 550 km altitude (normalized magnitude) both satellites often reaches naked-eye limiting ($<$ 6.0); (3) from a blackbody radiation model flux, peak components around $z$ band; (4) albedo near infrared range larger that optical range. Under assumption have same reflectivity, we estimate covering factor, $C_{\rm f}$, using model: factor ranges $0.18 \leq C_{\rm f} 0.92$. From multivariable analysis solar phase angle (Sun-target-observer), normalized magnitude, versus distribution presents moderate anti-correlation between them, suggesting magnitudes depend not only but also orientation along our line sight. However, impact astronomical Visorsat-designed remains serious. Thus, new countermeasures necessary further reduce sunlight.