Circular No. 2948 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 OCCULTATION OF SAO 80046 BY IAPETUS ON 1976 JUNE 16 G. E. Taylor, H.M. Nautical Almanac Office, informs us that the nominal region of visibility of this event (in a twilit sky) is limited to southeastern Brazil. The uncertainty is such that the occultation could occur instead in northeastern Brazil, Uruguay or eastern Argentina. The mid-time of occultation is predicted for 21h33m UT, and the duration is unlikely to be more than 2 min. COMET WEST (1975n) The following precise positions have been reported: 1975/76 UT R. A. (1950) Decl. m1 Observer Dec. 6.07744 20 33 59.14 -38 14 43.8 Torres 7.05904 20 34 57.91 -38 08 32.7 " Mar. 4.21680 21 56 10.19 + 5 14 02.2 Debehogne 4.22061 21 56 08.76 + 5 14 13.5 " 5.20271 21 50 16.24 + 5 59 08.5 " 5.20923 21 50 14.01 + 5 59 25.0 " 6.19957 21 44 53.68 + 6 38 59.5 " 6.21134 21 44 50.08 + 6 39 26.0 " 10.18761 21 28 07.48 + 8 37 50.6 " 10.20804 21 28 03.29 + 8 38 20.6 " 21.15342 21 03 17.03 +11 37 33.4 " 21.17420 21 03 15.03 +11 37 48.3 " 22.15138 21 01 46.91 +11 49 30.4 " 22.17216 21 01 45.13 +11 49 45.2 " 28.40545 20 53 35.07 +12 57 47.4 Torres 31.14410 20 50 21.28 +13 24 48.4 Vaghi Apr. 7.15804 20 42 19.14 +14 30 13.0 Codina 7.18478 20 42 17.20 +14 30 29.3 " 8.14145 20 41 09.99 +14 38 56.0 " 8.17478 20 41 07.60 +14 39 19.8 " 9.09319 20 40 01.76 +14 47 21.2 7.5 Bielicki 9.11979 20 40 00.81 +14 47 27.8 Debehogne 9.12604 20 40 00.37 +14 47 31.4 De Sanctis 10.07546 20 38 51.35 +14 55 50.3 7.2 Bielicki 10.12465 20 38 48.59 +14 56 10.4 Vaghi 10.12847 20 38 48.32 +14 56 12.1 " 10.14573 20 38 47.09 +14 56 21.2 Codina 10.17837 20 38 44.29 +14 56 48.2 " 11.10105 20 37 36.99 +15 04 39.9 6.8 Bielicki 12.12222 20 36 21.99 +15 13 08.7 Debehogne 12.12795 20 36 21.57 +15 13 11.6 " 18.11806 20 28 30.47 +16 01 15.6 " 18.12361 20 28 29.99 +16 01 18.0 " 26.48889 20 15 48.95 +16 59 45.1 Giclas 26.49271 20 15 48.51 +16 59 46.2 " 26.77572 20 15 20.34 +17 01 33.2 10 Tomita 30.34653 20 09 10.07 +17 22 11.2 Christy C. Torres (University of Chile, Cerro El Roble Station). Maksutov astrograph. Evidently nucleus D on Mar. 28. A 10-min 103a-0 exposure (without filter) on Mar. 28 shows a 5' elongated coma and a narrow main tail > 3o long oriented west-north-west; several streamers are superposed on a faint fan-type tail some 40o wide extending from the main tail and around to the north. H. Debehogne (Royal Observatory, Uccle). Mainly nucleus D in March. April observations at Pino Torinese Observatory and nucleus A. S. Vaghi and G. De Sanctis (Pino Torinese Obs.). Nucleus A. J. M. Codina (Fabra Obs.). Nucleus A. Computer: N. Torras. M. Bielicki and D. Bielicka (Warsaw Obs.). Micrometric. Nucleus D. H. L. Giclas (Lowell Obs.). Nucleus A. Measurer: M. L. Kantz. K. Tomita (Tokyo Astronomical Observatory). Nucleus A. J. W. Christy (U.S. Naval Observatory, Washington). Nucleus A. Further photographic observations of the separations and position angles of nuclei B and D (relative to nucleus A): Nucleus B. Mar. 31.14 UT, 21", 313o (Vaghi); 31.51, 21".7, 313o (Giclas); Apr. 3.49, 23".0, 315o (S. Murrell and C. Knuckles, New Mexico State University; measured by E. J. Reese); 7.49, 25".6, 313o (Murrell et al.); 9.12, 27", 312o (Debehogne); 10.13, 29", 310o (Vaghi); 12.12, 30", 310o (Debehogne); 20.49, 34".7, 306o (Giclas); 26.49, 37".5, 300o (Giclas); 26.78, 38".7, 303o (Tomita). Nucleus D. Mar. 31.14 UT, 9", 332o (Vaghi); 31.51, 9".5, 330o (Giclas); Apr. 3.49, 10".5, 327o (Murrell et al.); 7.49, 11".6, 327o (Murrell et al.); 9.12, 12", 323o (Debehogne); 10.13, 12", 321o (Vaghi); 12.12, 12", 318o (Debehogne); 18.12, 14", 318o (Debehogne); 20.49, 15".2, 317o (Giclas); 26.49, 19".2, 306o (Giclas); 26.78, 16".9, 313o (Tomita). J. Bortle, Brooks Observatory, provides the following visual magnitude differences: Apr. 8.37 UT, B 2-2.5 magnitudes fainter than A, D 1 magnitude fainter than A; 10.37, 2.5-3, 1.5; 12.37, 1.5, 1; 13.37, 1.2, 0.6; 23.31, 1.3, 1.1; 24.29, 1.8, 0.2. Selected recent total visual magnitude estimates and tail information: Apr. 23.31 UT, 6.3, 2o.25 in p.a. 268o-295o (Bortle, 10 x 50 binoculars); 27.42, 7.4, 1o in 269o (P. Maley, Houston, Texas, 13-cm refractor); May 1.06, 8.0, 7' in 273oo (F. Popperl, Bad Reichenhall, Germany, 20-cm reflector); 4.42, 7.9, 0o.8 in 265o (Maley); 6.04, 8.4, 5' in 276o (Popperl); 7.38, 8.0, 0o.6 in 265o (Maley); 9.28, 7.9, - (P. Collins, Littleton, Mass., 10-cm refractor). 1976 May 11 (2948) Brian G. Marsden
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