Electronic Telegram No. 4380
Central Bureau for Astronomical Telegrams
Mailing address:  Hoffman Lab 209; Harvard University;
 20 Oxford St.; Cambridge, MA  02138; U.S.A.
e-mail:  cbatiau@eps.harvard.edu (alternate cbat@iau.org)
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Prepared using the Tamkin Foundation Computer Network


COMET C/2017 F1 (LEMMON)
     Another apparently asteroidal object found on CCD survey images taken by
G. J. Leonard with the Mount Lemmon 1.5-m reflector near Tucson (discovery
observations tabulated below) has been found to show cometary appearance on
images taken by CCD astrometrists elsewhere.

     2017 UT             R.A. (2000) Decl.       Mag.   Observer
     Mar. 20.19190    8 42 49.50   +37 01 41.8   21.7   Leonard
          20.19616    8 42 49.11   +37 01 43.7   21.7     "
          20.20041    8 42 48.84   +37 01 44.6   20.7     "
          20.20467    8 42 48.42   +37 01 45.3   21.0     "
          20.32004    8 42 39.86   +37 02 17.4   21.2     "
          20.33129    8 42 39.02   +37 02 20.0   22.0     "
          20.34323    8 42 38.06   +37 02 22.7            "
          20.35464    8 42 37.14   +37 02 25.4            "
          21.15450    8 41 38.69   +37 05 56.9   21.4     "
          21.16637    8 41 37.93   +37 06 00.4            "
          21.22218    8 41 33.75   +37 06 14.8            "
          21.23434    8 41 32.97   +37 06 18.7   21.6     "
          21.24634    8 41 32.13   +37 06 21.7            "

G-band images taken by W. H. Ryan and E. V. Ryan with the Magdalena Ridge
Observatory 2.4-m f/8.9 reflector on Mar. 22.2 UT show a very faint short
tail in p.a. about 135 deg; the magnitude was measured to be 20.5-20.9.
Twenty stacked 60-s exposures taken by H. Sato, Tokyo, Japan, with a
0.51-m f/6.8 astrograph (+ luminance filter) near Mayhill, NM, USA, on Mar.
23.23 show the object appearing softer than nearby stars, but the coma was
uncertain and no tail is seen; the w-band magnitude was 21.6 as measured
within a circular aperture of radius 4".9.  Ten stacked 180-s unfiltered
images taken by G. Favero and R. Furgoni with a 0.80-m f/4 reflector at the
Osservatorio del Celado (Castello Tesino, Italy) on Mar. 27.8
show a diffuse appearance and a clear elongation toward p.a. about 290 deg.
     The available astrometry, the following preliminary retrograde parabolic
orbital elements by G. V. Williams (from 56 observations spanning Mar. 20-
Apr. 1), and an ephemeris appear on MPEC 2017-G06.

     T = 2017 Nov. 26.7881 TT         Peri. =  64.1079
                                      Node  = 158.7538  2000.0
     q = 4.517387 AU                  Incl. = 146.4927


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

                         (C) Copyright 2017 CBAT
2017 April 2                     (CBET 4380)              Daniel W. E. Green