Contents. planet: 7 -Uranus satellites: U16-Caliban: 12, U17-Sycorax: 27 total number: 39 type: absolute dates: 1984-1998 observatory: 675 - Palomar Mountain 1001 - The University of Hawaii - ??? 950 - La Palma - 950 709 - Cloudcroft (???) 696 - Whipple Observatory (Mt. Hopkins) - 696 568 - Mauna Kea - 568 1002 - Anglo-Australian Observatory - ??? 807 - Cerro Tololo Interamerican Observatory - 807 Reference. 6764 = IAU Circular No. 6764, 1997, October 31 1997IAUC_6764____1G 6771 = IAU Circular No. 6771, 1997, November 14 1997IAUC_6771____3F 6780 = IAU Circular No. 6780, 1997, November 29 1997IAUC_6780____1L 6833 = IAU Circular No. 6833, 1998, March 7 1998IAUC_6833____1M 6869 = IAU Circular No. 6869, 1998, April 7 1998IAUC_6869____1S 6870 = IAU Circular No. 6870, 1998, April 7 1998IAUC_6870____1G Informations. relative to: absolute reference frame: astrometric centre of frame: geocentre epoch of equinox: J2000 time scale: UTC reduction: no information coordinates: absolute diff. refraction: no information receptor: 1 - CCD 2 - photographic 3 - unknown telescope: 1 - COSMIC CCD camera on the Hale 5-m telescope at Palomar 2 - The University of Hawaii's 2.2-m reflector 3 - 2.5-m Isaac Newton Telescope, La Palma 4 - Cloudcroft. 0.6-m f/7 Ritchey-Chretien 5 - Mt. Hopkins. 1.2-m f/8 reflector 6 - Mauna Kea. Canada-France-Hawaii Telescope (photographic) 7 - Anglo-Australian Observatory. 4-m reflector, CCD 8 - Cerro Tololo Interamerican Observatory. 4-m reflector, CCD observers: 1 - B.J.Gladman, P.D.Nicholson, J.A.Burns, J.J.Kavelaars 2 - P.D.Nicholson, B.J.Gladman, J.A.Burns, J.J.Kavelaars 3 - W.Offutt 4 - D.J.Tholen (assisted by C.Herrick and R.J.Whiteley) 5 - A.Fitzsimmons, M.E.Fletcher, M.J.Irwin, assisted by P.Sorenson, M.Asif 6 - C.W.Hergenrother 7 - S.Lilly, M.-C.Hainaut, O.Le Fevre, M.Dussert. Measurer B. Gladman 8 - D.P.Cruikshank. Measurer B. J. Gladman 9 - M.J.Holman, W.R.Brown 10 - R.M.Smith, J.B.Jones, D.Windridge. Measurer B. Gladman 11 - P.Hall, D.Graham. Measurer J.J.Kavelaars data included in standard data file: no Comments. DISCOVERY OF SATELLITES OF URANUS B. J. Gladman, Canadian Institute for Theoretical Astrophysics; P. D. Nicholson and J. A. Burns, Cornell University; and J. J. Kavelaars, McMaster University, report the discovery of two probable distant satellites of Uranus on CCD frames obtained with the COSMIC camera on the Hale 5-m telescope at Palomar. The objects were detected by Gladman in early October on a set of twelve 360-s frames obtained on Sept. 6 and 7. Reference: IAU Circular No. 6764, 1997 October 31. evaluation: The values of O-C were calculated by N.Emelianov with the keplerian orbit ephemerides according to the elements published in IAU Circular No. 6870, 1998 April 7 IAU Circular No. 6869, 1998 April 7 Orbits of satellites of Uranus Uranus XVI = S/1997 U 1 = Caliban Osculating orbit: Epoch = 1998 July 6.0 TT Semi-major axes: 0.047921 AU Mean motion: 0.621291 degree/day Eccentricity: 0.082347 Inclination: 139.6813 degree Moment at perihelia: 1998 Apr. 19.6463 TT Perihelia from ascending node: 339.4621 degree Longitude of ascending node: 174.9928 degree Distance at perihelia: 0.043975 AU Period: 579 days Reference: IAU Circular No. 6870, 1998 April 7 Uranus XVII = S/1997 U 2 = Sycorax Osculating orbit: Epoch = 1998 July 6.0 TT Semi-major axes: 0.081643 AU Mean motion: 0.279383 degree/day Eccentricity: 0.509386 Inclination: 152.6686 degree Moment at perihelia: 1997 June 16.0390 TT Perihelia from ascending node: 18.0055 degree Longitude of ascending node: 255.8085 degree Distance at perihelia: 0.040055 AU Period: 1289 days Reference: IAU Circular No. 6869, 1998 April 7 Format. 1. Year of the moment of observation 2. Month of the moment of observation 3. Day of the moment of observation with decimals 4. Number of satellite : 16 for Caliban, 17 for Sycorax 5. Hour of right ascension (alpha, h) 6. Minute of right ascension (alpha, m) 7. Second of right ascension (alpha, s) 8. Degree of declination (delta, deg) 9. Minute of declination (delta, ' ) 10. Second of declination (delta, '' ) 11. O-C(alpha) for alpha, arcsec 12. O-C(delta) for delta, arcsec 13. N reference 14. N observer 15. N observatory 16. N telescope 17. N receptor ------------------------------------------------------------------------------ N N Observer Year sat J2000 O-C N Observatory Month R.A. Decl. alpha delta N Telescope Day (UT) h m s deg ' '' '' '' N reference N Recept ------------------------------------------------------------------------------