[Iaude] CBET 4496: 20180319 : COMET C/2018 F1 (GRAUER)

quai at eps.harvard.edu quai at eps.harvard.edu
Mon Mar 19 15:42:59 EDT 2018


                                                  Electronic Telegram No. 4496
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 F1 (GRAUER)
     A. D. Grauer reports his discovery of a comet with a diffuse 5" coma on
four co-added CCD exposures taken in 2".1 seeing with the Mount Lemmon 1.5-m
reflector on Mar. 17 UT (discovery observations tabulated below).  The comet
also showed a tail 7" long in p.a. 260 degrees.

     2018 UT             R.A. (2000) Decl.       Mag.   Observer
     Mar. 17.34541   12 49 40.12   + 6 55 32.5   19.1   Grauer
          17.35057   12 49 40.00   + 6 55 36.5   19.0     "
          17.35571   12 49 39.86   + 6 55 40.4   19.0     "
          17.36087   12 49 39.74   + 6 55 45.2   19.1     "

B. M. Africano and G. J. Leonard obtained follow-up observations with the
Steward Observatory 1.0-m reflector at Mt. Lemmon on Mar. 17.5 UT; four
co-added 45-s CCD images reveal an 8" coma of mag 18.8-18.9 and a short,
diffuse tail about 7"-10" long in p.a. 250-260 degrees.
     R. Wainscoat, Y. Ramanjooloo, and R. Weryk report their independent
discovery of this comet on images obtained a couple of hours later with the
1.8-m Pan-STARRS1 Ritchey-Chretien telescope at Haleakala.  Their Mar. 17
discovery observations are tabulated below, along with Pan-STARRS1
observations identified subsequently by Weryk on 2017 Dec. 22, 2018 Jan. 17,
and Mar. 10.  On Mar. 17, Weryk noted that the object's image had a full-
width-at-half-maximum of about 2".0 (larger than the FWHM = 1".3 for nearby
stars) and an obvious tail extnending about 8" almost directly westward.

     2017 UT             R.A. (2000) Decl.       Mag.
     Dec. 22.64040   12 37 31.93   - 3 40 13.8   21.7
          22.64430   12 37 32.08   - 3 40 13.6   21.9
          22.64819   12 37 32.22   - 3 40 13.3   21.8
          22.65208   12 37 32.36   - 3 40 12.6   21.4

     2018 UT             R.A. (2000) Decl.       Mag.
     Jan. 17.65112   12 50 36.02   - 2 17 44.3   21.1
          17.65976   12 50 36.19   - 2 17 41.3   21.1
     Mar. 10.44914   12 52 03.71   + 5 27 15.5   19.7
          10.47060   12 52 03.28   + 5 27 31.6   19.8
          10.48141   12 52 03.07   + 5 27 39.8   19.6
          17.44429   12 49 37.92   + 6 56 50.3   19.7
          17.45829   12 49 37.59   + 6 57 01.3   19.7
          17.47231   12 49 37.25   + 6 57 12.2   19.7
          17.48635   12 49 36.91   + 6 57 23.1   19.7

Weryk also identified apparently asteroidal Mt. Lemmon observations obtained
on 2018 Feb. 23.4 UT, when the comet was at mag 19.5-19.9.  After the object
was posted on the Minor Planet Center's NEOCP/PCCP website, J.-F. Soulier
reported that unfiltered CCD observations obtained by A. Maury, J.-B. Vanssay,
and himself with a 0.4-m f/5.2 Ritchey-Chretien at San Pedro de Atacama,
Chile, on Mar. 19.2 show a 10" coma and a tail 23" long in p.a. 250 deg; they
measured red magnitude 19.2 in an aperture of radius 6".4.
     The available astrometry, the following nearly parabolic orbital elements
by G. V. Williams (from 57 observations spanning 2017 Dec. 22-2018 Mar. 19),
and an ephemeris appear on MPEC 2018-F42.

                    Epoch = 2018 Dec. 28.0 TT
     T = 2018 Dec. 14.07301 TT        Peri. =  71.62193
     e = 0.9908123                    Node  = 177.29058 2000.0
     q = 2.9931078 AU                 Incl. =  46.07224


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

                         (C) Copyright 2018 CBAT
2018 March 19                    (CBET 4496)              Daniel W. E. Green



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