[IAUC] CBET 4001: 20141018 : COMET C/2013 A1 (SIDING SPRING)

[quai en eps.harvard.edu]

                                                  Electronic Telegram No. 4001
Central Bureau for Astronomical Telegrams
INTERNATIONAL ASTRONOMICAL UNION
CBAT Director:  Daniel W. E. Green; Hoffman Lab 209; Harvard University;
 20 Oxford St.; Cambridge, MA  02138; U.S.A.
e-mail:  cbatiau en eps.harvard.edu (alternate cbat en iau.org)
URL http://www.cbat.eps.harvard.edu/index.html
Prepared using the Tamkin Foundation Computer Network


COMET C/2013 A1 (SIDING SPRING)
     J. Crovisier, P. Colom, N. Biver, and D. Bockelee-Morvan, LESIA,
Observatoire de Paris, report the detection of the 18-cm OH lines in comet
C/2013 A1 with the Nancay radio telescope.  This detection was favored by the
enhanced continuum background, as the comet was close to the Galactic plane.
Using the Galactic continuum from the 1420-MHz maps of Reich et al. (2001,
A.Ap. 376, 881), Crovisier et al. derive OH production rates of 1.3 (+/- 0.3)
x 10**28 molecules/s (average of data from Oct. 5-8) and 3.3 (+/- 0.4) x
10**28 molecules/s (average of data from Oct. 11-13).  This latter value is
possibly overestimated due to uncertain Galactic background.

     S. Nakano, Sumoto, Japan, writes that his latest orbital elements (from
1293 astrometric observations spanning 2012 Oct. 4-2014 Oct. 12; mean residual
0".53), given below, show that comet C/2013 A1 will make a close approach to
Mars on Oct. 19.77 TT, at a distance of 0.000942 AU.  He finds original 1/a
= +0.000025 and future 1/a = +0.000104 (+/- 0.000001).

                    Epoch = 2014 Oct. 30.0 TT
     T = 2014 Oct. 25.30223 TT        Peri. =   2.42312
     e = 1.0004531                    Node  = 300.97645 2000.0
     q = 1.3987148 AU                 Incl. = 129.04284

     Visual total-magnitude and coma-diameter estimates:  July 2.82 UT, 11.9,
1' (M. Mattiazzo, Swan Hill, Victoria, Australia, 20-cm reflector); 21.34,
11.5, 1' (A. Amorim, Florianopolis, Brazil, 0.18-m reflector); Aug. 9.34,
10.1, 3' (M. Goiato, Aracatuba, Brazil, 0.22-m reflector); Sept. 3.75, 9.6,
2'.5 (P. Camilleri, Warners Bay, Australia, 0.40-m reflector); 22.42, 9.7, 2'
(Camilleri, 0.20-m reflector); Oct. 1.44, 10.6, 2' (Camilleri, 0.40-m
reflector); 15.42, 11.4, 1'.7 (K. Yoshimoto, Yamaguchi, Japan, 0.25-m
reflector).


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      superseded by text appearing later in the printed IAU Circulars.

                         (C) Copyright 2014 CBAT
2014 October 18                  (CBET 4001)              Daniel W. E. Green