Jay Respler posted his observed magnitudes for the OneWeb satellite constellation here: satobs.org/seesat/Dec-2020/0058.html. The mean magnitude adjusted to the standard satellite distance of 1000 km is 7.4 +/- 0.2. The dispersion of the 34 individual data points is 0.9 magnitude. The mean magnitude and dispersion are consistent with OneWeb values recorded by the MMT automated observatory in Russia. I posted the results of that study here: https://arxiv.org/abs/2012.05100. The large dispersion of OneWeb magnitudes is probably due to their complex shape. The satellite bus has a boxy form with dish-like antennas mounted on short arms and a pair of large solar panels attached to longer arms. Satellite attitude (orientation) contributes strongly to the observed brightness of such complicated bodies. One difference between the two data sets is that Respler's magnitudes show a stronger dependency on the illumination phase angle than do those of MMT. The R-squared values of the correlations are 0.26 and 0.04, respectively. The reason for the stronger correlation is not known with certainty, however it might be related to altitude. Only 4 of the satellites observed by Respler had reached their nominal 1200 km orbit. The others were still in the ascent phase at an average height of 689 km. If attitude is being held constant during ascent that could explain the correlation. Tony Mallama _______________________________________________ Seesat-l mailing list http://mailman.satobs.org/mailman/listinfo/seesat-lReceived on Tue Dec 15 2020 - 09:43:11 UTC
This archive was generated by hypermail 2.4.0 : Tue Dec 15 2020 - 15:43:12 UTC