[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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