We present results of visible wavelengths spectroscopic measurements (0.45 to
0.72 microns) of two binary asteroids, obtained with the 1-m telescope at the
Wise Observatory on January 2008. The asteroids (90) Antiope and (1509)
Esclangona were observed to search for spectroscopic variations correlated with
their rotation while presenting different regions of their surface to the
viewer. Simultaneous photometric observations were performed with the Wise
Observatory's 0.46-m telescope, to investigate the rotational phase behavior
and possible eclipse events. (90) Antiope displayed an eclipse event during our
observations. We could not measure any slope change of the spectroscopic albedo
within the error range of 3%, except for a steady decrease in the total light
flux while the eclipse took place. We conclude that the surface compositions of
the two components do not differ dramatically, implying a common origin and
history. (1509) Esclangona did not show an eclipse, but rather a unique
lightcurve with three peaks and a wide and flat minimum, repeating with a
period of 3.2524 hours. Careful measurements of the spectral albedo slopes
reveal a color variation of 7 to 10 percent on the surface of (1509)
Esclangona, which correlates with a specific region in the photometric
lightcurve. This result suggests that the different features on the lightcurve
are at least partially produced by color variations and could perhaps be
explained by the existence of an exposed fresh surface on (1509) Esclangona.Comment: 21 pages, 14 figures, 1 table, accepted for publication in
Meteoritics & Planetary Science (MAPS
