Circular No. 2855 Central Bureau for Astronomical Telegrams INTERNATIONAL ASTRONOMICAL UNION Postal Address: Central Bureau for Astronomical Telegrams Smithsonian Astrophysical Observatory, Cambridge, MA 02138, U.S.A. Cable Address: SATELLITES, NEWYORK Western Union: RAPID SATELLITE CAMBMASS PROBABLE NEW SATELLITE OF JUPITER Precise positions of the object reported on IAUC 2845: 1975 UT R. A. (1950) Decl. Mag. Observer Sept.30.31250 1 17 26.47 + 7 02 53.O 21 Kowal Oct. 1.31736 1 17 00.54 + 7 00 11.3 " 2.39444 1 16 32.74 + 6 57 06.3 " 6.26834 1 14 54.18 + 6 45 15.0 Roemer 6.33287 1 14 52.52 + 6 45 02.7 " C. Kowal (Hale Observatories). 122-cm Schmidt telescope, Palomar Mountain. The second declination is uncertain. E. Roemer and M. A. Daniel (Steward Observatory, Kitt Peak Station). 229-cm reflector. Measurer: C. C. McCarthy. Computations by K. Aksnes and B. G. Marsden, Center for Astrophysics, Harvard and Smithsonian Observatories, suggest that the object is indeed a satellite, although it is not clear whether its orbit is direct or retrograde. The departure from great-circle motion is 0'.4. Attempts to represent the observations with a heliocentric orbit were not satisfactory. The following ephemeris should suffice to locate the object, although observations during the forthcoming dark of the moon will be rendered difficult by the object's proximity to Jupiter (dR.A. and dDecl. are the offsets from Jupiter). Astronomers with access to large telescopes are therefore strongly urged to attempt to photograph the probable satellite well after new moon (if possible even after first quarter on Nov. 10), for by the following new moon the ephemeris could otherwise be in error by a substantial fraction of a degree (and the object will be significantly fainter). 1975 ET R. A. (1950) Decl. dR.A. dDecl. Oct. 10 1 13.26 + 6 33.3 -2m12 +18'9 15 1 11.39 + 6 16.3 -1.57 +17.0 20 1 09.52 + 5 58.6 -0.94 +14.2 25 1 07.77 + 5 40.8 -0.25 +10.9 30 1 06.13 + 5 23.2 +0.44 + 6.9 Nov. 4 1 04.62 + 5 06.4 +1.12 + 2.7 9 1 03.23 + 4 50.9 +1.72 - 1.6 14 1 01.99 + 4 37.0 +2.24 - 5.8 19 1 00.91 + 4 25.0 +2.67 - 9.7 1975 October 23 (2855) Brian G. Marsden
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