[Iaude] CBET 4484: 20180207 : COMET C/2018 B1 (LEMMON)

quai at eps.harvard.edu quai at eps.harvard.edu
Wed Feb 7 12:33:03 EST 2018


                                                  Electronic Telegram No. 4484
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 C/2018 B1 (LEMMON)
     An apparently asteroidal object discovered on 2018 Jan. 25 in the course
of the Mount Lemmon Survey on images taken by A. D. Grauer (discovery
observations tabulated below) has been found to show cometary appearance by
CCD astrometrists elsewhere.

     2018 UT             R.A. (2000) Decl.       Mag.   Observer
     Jan. 25.14389    3 50 50.57   +37 35 47.0   19.4   Grauer
          25.14920    3 50 50.20   +37 35 44.9   19.4     "
          25.15448    3 50 49.82   +37 35 43.7   19.8     "
          25.15974    3 50 49.49   +37 35 41.9   19.6     "

After the object was posted on the Minor Planet Center's NEOCP webpage,
W. H. Ryan reported that images taken by E. V. Ryan and himself on 2018 Jan.
25.2 and 26.1 UT show cometary appearance with a distinct tail in p.a. about
70 degrees and 50 degrees (respectively) on the two nights; the point-spread
function for the comet's head showed it to be 1.5-2 times that of nearby
stars, and the magnitude was found to be 19.3-19.6.  P. Birtwhistle (Great
Shefford, Berkshire, England) writes that his images obtained with a 0.40-m
f/6 Schmidt-Cassegrain reflector show that the object is possibly slightly
elongated towards p.a 75 degrees, extending about 5" from the center of light
on Jan. 31.78 and about 9" on Feb. 1.96; on the latter date, the magnitude
was found to be 19.8 and the object's full-width-at-half-maximum was only
marginally larger than that of nearby stars of similar brightness (4".3 vs.
3".8-4".0).
     The available astrometry (including single-night observations obtained
with the 1.8-m Pan-STARRS1 Ritchey-Chretien telescope at Haleakala on 2017
Jan. 16.5 and 28.5 UT, when the object's magnitude was 22.1-22.8, and
identified by G. V. Williams in Minor Planet Center data), the following
hyperbolic orbital elements, and an ephemeris appear on MPEC 2018-C27.

                    Epoch = 2018 Mar. 23.0 TT
     T = 2018 Mar. 30.55161 TT        Peri. =  68.35212
     e = 1.0030661                    Node  = 133.15846 2000.0
     q = 5.1170259 AU                 Incl. = 162.42299


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      superseded by text appearing later in the printed IAU Circulars.

                         (C) Copyright 2018 CBAT
2018 February 7                  (CBET 4484)              Daniel W. E. Green



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