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

C/2018 W1 (Catalina) at perihelion

Dominic Ford, Editor
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Comet C/2018 W1 (Catalina) will make its closest approach to the Sun, at a distance of 1.36 AU.

From Fairfield the 2019 apparition of C/2018 W1 (Catalina) will progress as follows:

Begin typing the name of a town near to you, and then select the town from the list of options which appear below.
11 May 2019 – C/2018 W1 (Catalina) at perihelion
20 Apr 2019EridanusNot observable
22 Apr 2019EridanusNot observable
24 Apr 2019EridanusNot observable
26 Apr 2019EridanusNot observable
28 Apr 2019EridanusNot observable
30 Apr 2019EridanusNot observable
02 May 2019EridanusNot observable
04 May 2019EridanusNot observable
06 May 2019EridanusNot observable
08 May 2019EridanusNot observable
10 May 2019EridanusNot observable
12 May 2019EridanusNot observable
14 May 2019EridanusNot observable
16 May 2019EridanusNot observable
18 May 2019EridanusNot observable
20 May 2019EridanusNot observable
22 May 2019EridanusNot observable
24 May 2019LepusNot observable
26 May 2019LepusNot observable
28 May 2019ColumbaNot observable
30 May 2019ColumbaNot observable

A more detailed table of C/2018 W1 (Catalina)'s position on each night is available here. A diagram of the orbit of C/2018 W1 (Catalina) is available here.

At the moment of perihelion it will not be observable – it will reach its highest point in the sky during daytime and will be 28° below the horizon at dusk.

Finder chart

The chart below shows the path of C/2018 W1 (Catalina) 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.

Based on the magnitude parameters published for this comet by the BAA Comet Section, we estimate that it may be around mag 11 at perihelion. This estimate is based on observations that the BAA has received from amateur astronomers, assuming that its current level of activity will remain constant.

You will probably require a telescope to see this comet. It is unlikely to be visible through bird-watching binoculars, and even less likely to be visible to the unaided eye.

The comet's position at perihelion will be:

Object Right Ascension Declination Constellation Magnitude
Comet C/2018 W1 (Catalina) 04h16m30s 20°56'S Eridanus 11.4

The coordinates are given in J2000.0.

The sky on 11 May 2019
Twilight ends
Twilight begins

7-day old moon
Waxing Gibbous


7 days old

Rise Culm. Set
Mercury 05:16 12:07 18:57
Venus 04:41 11:13 17:45
Moon 11:43 19:06 01:43
Mars 07:44 15:22 22:59
Jupiter 22:28 03:06 07:44
Saturn 00:25 05:07 09:50
All times shown in EDT.


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 21 Apr 2021.

Image credit

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






Color scheme