[Iaude] CBET 4585: 20181218 : COMET 46P/WIRTANEN

quai at eps.harvard.edu quai at eps.harvard.edu
Mon Dec 17 20:39:06 EST 2018


                                                  Electronic Telegram No. 4585
Central Bureau for Astronomical Telegrams
Mailing address:  Hoffman Lab 209; Harvard University;
 20 Oxford St.; Cambridge, MA  02138; U.S.A.
e-mail:  cbatiau at eps.harvard.edu (alternate cbat at iau.org)
URL http://www.cbat.eps.harvard.edu/index.html
Prepared using the Tamkin Foundation Computer Network


COMET 46P/WIRTANEN
     E. Jehin, Y. Moulane, J. Manfroid, and F. Pozuelos, STAR Institute,
University of Liege, report on observations made of comet 46P with the 0.60-m
Ritchey-Chretien telescopes at the Oukaimeden Observatory in Morocco (during
Dec. 9.77-10.08 UT) and at La Silla in Chile (during Dec. 10.04-10.29); a
total of 12.5 hours of images were obtained continuously through CN and C_2
filters.  An exposure time of 300 s was used for each filter.  After data
reduction and flux calibration, aperture photometry was performed with a 20"
aperture (as well as 10" and 50"), revealing a very clear periodic signal in
the CN data with two maxima and two assymetric minima.  The CN datasets from
each telescope were phased very well, with a best period of 0.383 day or 9.19
hr, matching data obtained on several nights around this tiime (the Fourier
peak giving an uncertainty of 0.002 day on the whole interval).  The CN
phase diagram shows an amplitude of about 0.24 magnitude.  The C_2 periodic
signal is, however, not that clear, and no value has been derived so far.

     Additional total-visual-magnitude and coma-diameter estimates (cf. CBET
4571):  Nov. 13.00 UT, 6.2, 27' (J. J. Gonzalez, Asturias, Spain, 12x45
monocular); 13.98, 6.8, 10' (W. Souza, Sao Paulo, Brazil, 0.10-m refractor);
16.00, 5.7, 32' (Gonzalez); 26.00, 5.4, 40' (M. Goiato, Aracatuba, Brazil,
4x50 binoculars); 30.80, 4.8, 110' (Gonzalez); Dec. 2.86, 4.9, 40' (T.
Scarmato, Calabria, Italy, 7x50 binoculars; light pollution); 6.04, 4.5, 60'
(Goiato); 6.85, 5.3, & 15' (S. J. O'Meara, Maun, Botswana, naked eye); 7.81,
4.4, 60' (Scarmato); 9.21, 4.3, 60' (Goiato); 10.54, 4.4, 80' (Y. Nagai,
Gunma, Japan, naked eye); 11.07, 3.9, 90' (Goiato, naked eye); 11.38, 4.5,
1 deg (O'Meara); 11.86, 4.1, 70' (Gonzalez, Leon, Spain, 12x45 monocular);
12.35, 4.4, 30' (O'Meara; crescent moon); 13.26, 4.5, 54' (M.-T. Hui, Kitt
Peak, AZ, USA, naked eye); 14.00, 4.1, 75' (Gonzalez); 14.31, 3.9, & 1 deg
(O'Meara; crescent moon); 15.31, 4.0, & 30' (O'Meara; moonlight); 15.80, 4.1,
30' (R. Haver, Frasso Sabino, Italy, naked eye); 16.06, 4.1, 60' (Souza,
10x42 binoculars); 16.19, 3.6, > 90' (Goiato, naked eye); 18.08, 3.9:, 60'
(Goiato, 4x50 binoculars; moonlight).


NOTE: These 'Central Bureau Electronic Telegrams' are sometimes
      superseded by text appearing later in the printed IAU Circulars.

                         (C) Copyright 2018 CBAT
2018 December 18                 (CBET 4585)              Daniel W. E. Green



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