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21.
Deep imaging was performed with the Subaru Telescope on Mauna Keacentered on the position of the KBO (24952) 1997 QJ4 on 2half-nights during October 2002. A deep search for evidence of a dustcoma was conducted which could be indicative of cometary activity downto a limit of mV = 31 mag arcsec-2. No coma was detected, and from this sensitive upper limits on dust production can be set at Q <0.01 kg s-1. Brightness variations consistent with rotationalmodulation were seen, implying a period of rotation longer than 4 hrs,with a range > 0.3 mag corresponding to a minimum projected axis ratioof 1:1.3. 相似文献
22.
J.L. Elliot J.H. Elias R.G. French Jay A. Frogel W. Liller K. Matthews K.J. Meech D.J. Mink P.D. Nicholson B. Sicardy 《Icarus》1983,56(2):202-208
Occultation profiles for the nine confirmed Uranian rings obtained from Las Campanas, the European Southern Observatory, and Cerro Tololo on 15–16 August 1980 are compared. The α ring shows a “double-dip” structure; the η ring shows a broad and narrow component (similar to Saturn's F ring); and the ε ring shows six features that appear in the data from all three observatories. Diffraction fringes appear at the edges of several of the occultation profiles. 相似文献