143P/Kowal-Mrkos (0143P)
TRY AGAIN 2026
Type: Periodic
Perihelion date: 1 January 2027
Perihelion distance (q): 2.5
Aphelion distance (Q) : 6.3
Period (years): 9.2
Eccentricity (e): 0.43
Inclination (i): 5.7
JPL orbit diagram
COBS lightcurve
Atlas
During September of 1984, C. T. Kowal (Palomar Observatory, California, USA) was
examining photographic plates exposed earlier in the year with the 1.2-m Schmidt
telescope, when he found the unmistakable trail of a comet. The trail appeared on
images exposed on 23 and 30 April 1984. Kowal estimated the magnitude as 15 and
described the comet as "almost stellar, with a faint but definite coma."
B. G. Marsden quickly realized the Kowal's object was identical to a minor planet
found by A. Mrkos (Klet Observatory, Czech Republic) on a photographic plate
exposed on 2 May. Mrkos had noted that the minor planet (designated 1984 JD) was
stellar on the first image, but slightly diffuse on the second. The magnitude was given
as 16.0. During March of 2000, the Lincoln Laboratory Near-Earth Asteroid Research
(LINEAR) project provided observations of an asteroidal object from 9 and 13 March,
which was subsequently designated 2000 ET90.
Following additional observations by LINEAR on 4 and 8 April, G. V. Williams (Central
Bureau for Astronomical Telegrams) noted the apparently cometary orbit and
requested further observations. Prediscovery images were subsequently reported by
LINEAR for 7 February (magnitude 19.2-19.7), and by the Catalina Sky Survey for 1
March (magnitude 17.2-17.4). Another observation was subsequently found by the
Lowell Observatory Near-Earth Object Search (LONEOS) program for 2 April
(magnitude 16.9).
From the subsequent orbit spanning nearly two months, Marsden suspected this was
comet Kowal-Mrkos and an independent suggestion was also made by C. W.
Hergenrother. Marsden quickly confirmed that 2000 ET90 was identical to Kowal-
Mrkos. He also noted that the prediction for the 2000 return was 125 days too late.
Observations (VEMag = visual equivalent magnitude)
Date
10x10 mag
Error
VEmag
Coma '
26-Dec-17
18.31
0.13
18.0
0.2
21-Jan-18
18.20
0.06
18.1
0.2
14-Feb-18
17.89
0.01
17.8
0.2
21-Feb-18
17.75
0.03
17.5
0.2
11-Mar-18
17.32
0.06
17.2
0.2
20-Mar-18
17.24
0.02
16.9
0.2
08-Apr-18
16.57
0.01
16.0
0.3
21-Apr-18
16.86
0.05
16.5
0.2
10-May-18
17.47
0.04
17.2
0.2
16-May-18
17.53
0.03
17.3
0.2
02-Jun-18
17.79
0.05
17.5
0.2
06-Jul-18
18.35
0.08
17.9
0.2
08-May-19
19.50
0.13
19.2
0.2