Circular No. 4189 Central Bureau for Astronomical Telegrams INTERNATIONAL ASTRONOMICAL UNION Postal Address: Central Bureau for Astronomical Telegrams Smithsonian Astrophysical Observatory, Cambridge, MA 02138, U.S.A. TWX 710-320-6842 ASTROGRAM CAM Telephone 617-495-7244/7440/7444 PERIODIC COMET HALLEY (1982i) R. P. McCoy, G. R. Carruthers, and R. R. Meier, Naval Research Laboratory; and C. B. Opal, University of Texas, Austin, report a rocket observation of P/Halley on Feb. 24.5 UT. High-quality images of the entire coma at wavelengths of H I 121.6 nm, O I 130.4 nm, and C I 156.1 and 165.7 nm, were obtained. The comae were easily detectable out to the following distances from the nucleus: H I, 5.0 x 10**6 km; O I, 1.5 x 10**6 km; and C I, 1.0 x 10**6 km. P. D. Feldman, T. N. Woods, K. Dymond, and D. Sahnow, Johns Hopkins University, also report rocket observations made on Feb. 26.5 UT. Ultraviolet spectra in the wavelength range 120 to 175 nm were obtained with a long-slit spectrograph giving 10" resolution along an 8' slit. In addition to the strong H I, O I and C I emissions noted above, several bands of the CO fourth positive system are seen, as is C II 133.5-nm emission, which shows a clear extension in the tailward direction. Both of these experiment payloads are being refurbished for more rocket flights on March 13.5. H. Pedersen, R. Vio, and R. M. West, European Southern Observatory, La Silla, telex that a clear disconnection event 9.3 deg from the nucleus was seen on Mar. 5.38 UT on images obtained with the ESO wide-field CCD camera through the standard IHW 426-nm filter. Four consecutive 10-min exposures showed an outward motion of ~ 11'/hr (~ 150 km/s projected). The tail length was > 15 deg. West also found that on Feb. 27.4 the nucleus was 8" across and elongated in p.a. ~ 250, while on subsequent days it appeared 2" or less in diameter and round, from red photographic plates (5-sec exposures). T. le Bertre reports infrared L (3.8 micron) magnitudes using a 30" diaphragm (cf. IAUC 4183): Feb. 24, 0.46; 25, 0.73; 26, 0.38; 27, 0.66; 28, 0.44; Mar. 1, 2.00; 2, 0.75; 3, 1.16. The episodic outbursts inducing day-to-day variations of up to 1.5 magnitudes are still occurring and could be periodic (P ~ 58 hr?). A particularly quiet state was noted on Mar. 1.4, with a significant change in colors. Further total visual magnitude estimates: Feb. 25.53 UT, 3.0 (R. Keen, Mt. Thorodin, CO, naked eye); 26.40, 2.8 (D. W. E. Green, near Guadeloupe, W.I., 7x50 binoculars, tail > 3 deg long); 28.52, 2.8 (Keen); Mar. 1.43, 3.2 (J. E. Bortle, Stormville, NY, 10x50 binoculars; tail length 1.5 deg); 2.43, 2.7 (Green, Cambridge, MA, 7x35 binoculars); 3.43, 3.5 (Bortle; tail length > 2 deg); 4.53, 2.9 (Keen); 6.43, 3.6 (Green, Cambridge, MA, 7x35 binoculars). 1986 March 7 (4189) Daniel W. E. Green
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