[Iaude] CBET 4712: COMET C/2019 Y4

quai at eps.harvard.edu quai at eps.harvard.edu
Sat Jan 11 14:27:48 EST 2020


                                                  Electronic Telegram No. 4712
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/2019 Y4 (ATLAS)
     A new object found on CCD images taken with a 0.5-m reflector at Mauna
Loa, Hawaii, in the course of the "Asteroid Terrestrial-Impact Last Alert
System" (ATLAS) search program (discovery observations tabulated below) on
2019 Dec. 28.6 UT was noted at that time as being a comet by Larry Denneau
of the ATLAS staff.  H. Flewelling, University of Hawaii, added that the
comet appears extended with a diffuse coma of diameter about 2" with no tail
from her measurements of the discovery images.

     2019 UT             R.A. (2000) Decl.       Mag.
     Dec. 28.59683   11 44 23.74   +30 49 19.4   19.6
          28.60028   11 44 23.80   +30 49 22.0   19.6
          28.60534   11 44 23.83   +30 49 25.1   19.5
          28.60822   11 44 24.05   +30 49 27.0   19.3
          28.62320   11 44 24.58   +30 49 38.1   19.5
          28.62504   11 44 24.54   +30 49 40.3   19.2

After the object was posted on the Minor Planet Center's PCCP webpage, other
CCD astrometrists have commented on the cometary appearance.  Ten stacked 60-s
exposures taken remotely by H. Sato, Tokyo, Japan, using a 0.43-m f/6.8
astrograph near Mayhill, NM, USA, on 2019 Dec. 30.5 UT show a stellar
appearance, but his follow-up exposures taken (as above) on 2020 Jan. 4.45
show a strongly condensed coma 8" in diameter with a 15" tail toward p.a.
280 degrees, and showing magnitude 18.9 as measured within a circular
aperture of radius 5".7.  L. Buzzi, Varese, Italy, notes that forty-five
stacked 60-s exposures taken with a 0.84-m f/3.5 reflector on 2019 Dec. 31.2
show a 10" coma elongated toward the northwest.  K. Sarneczky, Konkoly
Observatory, reports that three stacked 120-s unfiltered CCD images taken
with the 1.02-m reflector at Piszkesteto, Hungary, on 2020 Jan. 1.1 show a
moderately condensed coma 8" in diameter and no tail.  E. Bryssinck,
Kruibeke, Belgium, writes that ten stacked 120-s exposures apparently taken
on Jan. 6.2 remotely with an iTelescope 0.43-m f/6.8 reflector (with
luminance filter) at Nerpio, Spain, show a central condensation with a
faint circular coma of size 21" and a hint of a tail 17" long in p.a. 285
degrees.  Unfiltered images taken by C. Rinner and F. Kugel on Jan. 8.22
with a 0.4-m f/2.8 reflector at Dauban, France, show a coma about 20" in
size that is extended toward p.a. 300 degrees; the magnitude was 18.7-19.4
in an aperture of radius 5".8.
     The available astrometry has been published on MPEC 2020-A112.  S.
Nakano, Sumoto, has computed the following preliminary nearly parabolic
orbital elements from 178 observations spanning 2019 Dec. 28-2020 Jan. 9
(mean residual 0".49), which suggests an orbital period around 4400 years.

     T = 2020 May  31.0475 TT         Peri. = 177.4260
     e = 0.999054                     Node  = 120.5529  2000.0
     q = 0.252946 AU                  Incl. =  45.3637
     a = 267.25 AU

M. Meyer, Limburg, Germany, has noted the similarity of the orbit of the
Great Comet C/1844 Y1 and comet C/2019 Y4, adding that the intrinsic
brightness of the latter is much lower than that of the former.  Nakano
forwards a new evaluation of the observations of C/1844 Y1 by T. Kobayashi
from 41 observations spanning 1844 Dec. 24-1845 Mar. 12 (mean residual 5".2),
which yields the following orbital elements for epoch 1844 Dec. 20.0 TT:  T =
1844 Dec. 14.1897 TT, q = 0.250333 AU, e = 0.998957, Peri. = 177.4633
degrees, Node = 120.6095 deg, i = 45.5593 deg (equinox J2000.0) -- which
would suggest an orbital period of about 4000 yr.
     The following ephemeris by the undersigned from Nakano's orbital elements
above use photometric parameters H = 13.0 and 2.5n =  8 for the magnitudes.

Date    TT    R. A. (2000) Decl.     Delta      r     Elong.  Phase  Mag.
2019 12 03    11 26.40   +27 10.5    3.132    3.270    89.2    17.5  19.6
2019 12 08    11 30.38   +27 39.5    2.994    3.205    93.3    17.9  19.4
2019 12 13    11 34.17   +28 14.4    2.857    3.140    97.4    18.1  19.3
2019 12 18    11 37.74   +28 55.9    2.721    3.074   101.6    18.3  19.1
2019 12 23    11 41.06   +29 44.8    2.587    3.007   105.8    18.3  18.9
2019 12 28    11 44.06   +30 41.9    2.455    2.940   110.0    18.3  18.7
2020 01 02    11 46.69   +31 47.9    2.326    2.872   114.1    18.2  18.5
2020 01 07    11 48.90   +33 03.8    2.201    2.803   118.2    18.0  18.3
2020 01 12    11 50.60   +34 30.2    2.079    2.734   122.3    17.7  18.1
2020 01 17    11 51.70   +36 08.2    1.962    2.663   126.1    17.4  17.9
2020 01 22    11 52.06   +37 58.5    1.851    2.592   129.7    17.0  17.6
2020 01 27    11 51.54   +40 01.5    1.745    2.520   132.8    16.7  17.4
2020 02 01    11 49.94   +42 17.5    1.646    2.447   135.3    16.4  17.2
2020 02 06    11 47.03   +44 46.1    1.555    2.373   137.0    16.4  17.0
2020 02 11    11 42.52   +47 26.4    1.470    2.298   137.7    16.8  16.7
2020 02 16    11 36.01   +50 16.6    1.394    2.222   137.1    17.6  16.5
2020 02 21    11 27.02   +53 13.7    1.327    2.145   135.3    18.9  16.3
2020 02 26    11 14.96   +56 13.1    1.267    2.066   132.2    20.8  16.0
2020 03 02    10 59.15   +59 09.1    1.216    1.987   128.0    23.1  15.8
2020 03 07    10 38.91   +61 54.3    1.173    1.905   123.1    25.9  15.6
2020 03 12    10 13.67   +64 20.5    1.137    1.823   117.5    28.9  15.4
2020 03 17    09 43.34   +66 19.1    1.107    1.739   111.5    32.2  15.1
2020 03 22    09 08.69   +67 42.4    1.083    1.653   105.2    35.6  14.9
2020 03 27    08 31.60   +68 26.2    1.063    1.565    98.8    39.1  14.7
2020 04 01    07 54.63   +68 30.7    1.045    1.475    92.3    42.6  14.4
2020 04 06    07 20.04   +68 00.7    1.029    1.382    85.9    46.2  14.2
2020 04 11    06 49.15   +67 02.8    1.012    1.288    79.5    49.9  13.9
2020 04 16    06 22.18   +65 43.6    0.995    1.191    73.1    53.8  13.6
2020 04 21    05 58.64   +64 07.4    0.974    1.090    66.8    57.9  13.2
2020 04 26    05 37.60   +62 15.6    0.951    0.986    60.5    62.6  12.8
2020 05 01    05 17.98   +60 05.2    0.922    0.879    54.0    68.0  12.4
2020 05 06    04 58.68   +57 27.2    0.890    0.768    47.2    74.6  11.8
2020 05 11    04 38.78   +54 03.8    0.853    0.652    39.9    83.2  11.2


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

                         (C) Copyright 2020 CBAT
2020 January 11                  (CBET 4712)              Daniel W. E. Green



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