© Andy Roberts 1997. Pictured comet is C/1995 O1 Hale-Bopp.

Comet C/2019 U6 (Lemmon) reaches peak brightness

Dominic Ford, Editor
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Comet C/2019 U6 (Lemmon) is forecast to reach the brightest point in its 2020 apparition on 22 June. At that time, it will lie at a distance of 0.91 AU from the Sun, and at a distance of 0.83 AU from the Earth.

From San Diego on 22 June it will not be observable – it will reach its highest point in the sky during daytime and will be no higher than 6° above the horizon at dusk.

Begin typing the name of a town near to you, and then select the town from the list of options which appear below.

The events that comprise the 2020 apparition of C/2019 U6 (Lemmon) are as follows:

Date Event
18 Jun 2020Comet C/2019 U6 (Lemmon) passes perihelion
22 Jun 2020Comet C/2019 U6 (Lemmon) reaches peak brightness
28 Jun 2020Comet C/2019 U6 (Lemmon) passes perigee

The table below lists the times when C/2019 U6 (Lemmon) will be visible from San Diego day-by-day through its apparition:

Date Constellation Comet visibility
01 Jun 2020Canis MajorNot observable
03 Jun 2020Canis MajorNot observable
05 Jun 2020PuppisNot observable
07 Jun 2020PuppisNot observable
09 Jun 2020PuppisNot observable
11 Jun 2020PuppisNot observable
13 Jun 2020PuppisNot observable
15 Jun 2020HydraNot observable
17 Jun 2020HydraNot observable
19 Jun 2020HydraNot observable
21 Jun 2020HydraNot observable
23 Jun 2020HydraNot observable
25 Jun 2020SextansNot observable
27 Jun 2020SextansNot observable
29 Jun 2020SextansNot observable
01 Jul 2020SextansNot observable
03 Jul 2020SextansVisible from 21:09 until 21:12
Highest at 21:09, 21° above W horizon
05 Jul 2020LeoVisible from 21:09 until 21:22
Highest at 21:09, 23° above W horizon
07 Jul 2020LeoVisible from 21:08 until 21:31
Highest at 21:08, 25° above W horizon
09 Jul 2020LeoVisible from 21:07 until 21:40
Highest at 21:07, 28° above W horizon
11 Jul 2020VirgoVisible from 21:07 until 21:47
Highest at 21:07, 30° above W horizon

A more detailed table of C/2019 U6 (Lemmon)'s position on each night is available here. A diagram of the orbit of C/2019 U6 (Lemmon) is available here.

Finder chart

The chart below shows the path of C/2019 U6 (Lemmon) over the course of its apparition, as calculated from the orbital elements published by the Minor Planet Center (MPC). It is available for download, either on dark background, in PNG, PDF or SVG formats, or on a light background, in PNG, PDF or SVG formats. It was produced using StarCharter.

Comet brightnesses

Comets are intrinsically highly unpredictable objects, since their brightness depends on the scattering of sunlight from dust particles in the comet's coma and tail. This dust is continually streaming away from the comet's nucleus, and its density at any particular time is governed by the rate of sublimation of the ice in the comet's nucleus, as it is heated by the Sun's rays. It also depends on the amount of dust that is mixed in with that ice. This is very difficult to predict in advance, and can be highly variable even between successive apparitions of the same comet.

In consequence, while the future positions of comets are usually known with a high degree of confidence, their future brightnesses are not. For most comets, we do not publish any magnitude estimates at all. For the few comets where we do make estimates, we generally prefer the BAA's magnitude parameters to those published by the Minor Planet Center, since they are typically updated more often.

No estimate for the brightness of comet C/2019 U6 (Lemmon) is currently available.

The comet's position on 22 June 2020 will be:

Object Right Ascension Declination Constellation Magnitude
Comet C/2019 U6 (Lemmon) 09h24m00s 8°42'S Hydra 6.4

The coordinates are given in J2000.0.

The sky on 22 Jun 2020

The sky on 22 June 2020
Twilight ends
Twilight begins

1-day old moon
Waxing Crescent


1 day old

Rise Culm. Set
Mercury 06:43 13:41 20:38
Venus 04:07 10:58 17:49
Moon 06:51 14:15 21:36
Mars 00:43 06:35 12:27
Jupiter 21:26 02:31 07:35
Saturn 21:46 02:54 08:02
All times shown in PDT.


This event was automatically generated on the basis of orbital elements published by the Minor Planet Center (MPC) , and is updated whenever new elements become available. It was last updated on 13 May 2024.

Image credit

© Andy Roberts 1997. Pictured comet is C/1995 O1 Hale-Bopp.


San Diego



Color scheme