| Uranus spectroscopy and photometry 2019/12/03 by Christophe.P |
Spectroscopic results on Uranus from December 3rd. This is the first result of the two only complete clear nights I got since September equinoxe :( up to this day! No solid reference star was found for the photometry, and the data is the result of a cross analysis between three stars, with the priority given to HD9986, which is the G2V solar analog that served to calculate the spectroscopic albedo. As for Neptune, the magnitude and albedo values calculated for the Rc band is much brighter than the litterature (35% against around 20%). I have been examinated every possible source of problem, but found no one, and the difference far exceeds any error that could be linked to calculations, calibration or filter passband errors, so I'm short of explanations. On the other hand, results obtained from that night and the preceding (to be sent later) would show an interesting higher albedo in the V band of 1% (50% against 49%). I have taken some images with photometric filters in early January that show that the bright polar region of Uranus is now perceptible in the Johnson V band so this could be related. Added are comparisons with albedo and color spectra of Neptune, which show that Uranus is more reflective in green, red, and infrared, proving that the real color of that planet is less blue than Neptune.
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