Periodic Comet d'Arrest (1976e)

Further precise positions have been reported as follows: 1976 UT R. A. (1950) Decl. Observer July 18.71528 19 36 02.29 +18 38 54.4 Candy 20.68750 19 41 57.82 +17 37 04.7 " 31.22309 20 23 43.36 + 8 26 56.7 Helin Aug. 2.40729 20 34 46.84 + 5 38 17.0 " 3.93476 20 43 07.34 + 3 28 23.8 Waterfield 3.95556 20 43 14.02 + 3 26 35.9 " 7.08303 21 01 32.35 - 1 26 24.0 Codina 7.10560 21 01 40.27 - 1 28 36.6 " 17.68252 22 13 09.31 -19 47 59.6 Harwood 19.01084 22 22 28.25 -21 55 41.8 Rutter 19.22083 22 23 58.19 -22 14 53.3 Giclas 25.63542 23 06 44.04 -30 35 18.6 Candy 27.24062 23 16 31.90 -32 12 21.4 Giclas 28.42378 23 23 23.96 -33 16 08.3 Bus 30.69306 23 35 57.01 -35 01 50.6 C. Jekabsons Sept. 8.69375 0 15 25.17 -39 16 59.5 Candy 10.70451 0 22 07.26 -39 46 32.2 P. Jekabsons M. P. Candy, D. Harwood, C. Jekabsons and P. Jekabsons (Perth Observatory, Bickley). 33-cm astrograph (not 25-cm, cf. IAUC 2968). E. Helin and S. J. Bus (Palomar Mountain Observatory). Measurer: Bus. 46-cm Schmidt telescope. R. L. Waterfield, I. M. Purcell and G. H. Rutter (Woolston Observatory). Measurer: Waterfield. J. M. Codina (Fabra Observatory), Computer: N. Torras. H. L. Giclas (Lowell Observatory). Measurer: N. L. Kantz. G. K. G. Moore, Department of Physics, University of Wollongong, writes that a sequence of 5-min 103a-F exposures with the 46-cm f/5 reflector on Sept. 3.6-3.7 UT shows a small ejection moving at 20"/hr in a direction opposite to that of the comet's motion. Z. Sekanina, Center for Astrophysics, informs us that relatively favorable projection conditions will prevail between Oct. 1976 and Jan.-Feb. 1977 for detecting emissions of submillimeter-sized and larger debris from P/d'Arrest, extending essentially to the west of the nucleus, Because of the anticipated very low surface brightness of the feature, large Schmidt telescopes (or similar instruments) will be necessary to record it. The ephemeris is on IAUC 2900 and 2964. For best results calibrated panchromatic plates and a red filter should be used. High-quality negative observations should also be reported as they can provide an upper limit to the production rate of the debris. The following photoelectric observations were made by H. Debehogne, J. Surdej and A. Surdej with the 50-cm photometric reflector at the European Southern Observatory on Aug. 18.2 UT: diaphragm 5", V = 11.46, B-V = +0.71, U-B = +0.14; 15", 10.86, +0.55, +0.55; 20", 10.29, +0.68, +0.06; 30", 10.07, +0.63, +0.01. Selected total visual magnitude estimates and coma diameters: Aug. 22.24 UT) 6.0, 17' (K. Simmons, Switzerland, Florida, 14 x 100 binoculars); 25,24, 5.9, 20' (D. D. Meisel, Mees Observatory, 7 x 50 binoculars); 29.19, 5,7, 20' (Simmons); Sept. 12.31, 5.8, 10' (P. Maley, Houston, Texas, 7 x 35 binoculars); 15.29, 6.0, 8' (Maley); 22.30, 6.4, 10' (Maley; tail 0o.5 long in p.a. 355o).