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

C/2018 Y1 (Iwamoto) reaches its brightest

Dominic Ford, Editor
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Comet C/2018 Y1 (Iwamoto) is forecast to reach its brightest. It will lie at a distance of 1.28 AU from the Sun, and at a distance of 0.30 AU from the Earth.

From Fairfield the 2019 apparition of C/2018 Y1 (Iwamoto) 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.
07 Feb 2019 – C/2018 Y1 (Iwamoto) at perihelion
13 Feb 2019 – C/2018 Y1 (Iwamoto) reaches its brightest
13 Feb 2019 – C/2018 Y1 (Iwamoto) at perigee
23 Jan 2019VirgoVisible from 03:20 until 06:04
Highest at 05:31, 29° above S horizon
25 Jan 2019VirgoVisible from 02:57 until 06:02
Highest at 05:17, 30° above S horizon
27 Jan 2019VirgoVisible from 02:32 until 06:01
Highest at 05:01, 31° above S horizon
29 Jan 2019VirgoVisible from 02:03 until 06:00
Highest at 04:43, 33° above S horizon
31 Jan 2019VirgoVisible from 01:28 until 05:58
Highest at 04:23, 35° above S horizon
02 Feb 2019VirgoVisible from 00:46 until 05:56
Highest at 03:59, 38° above S horizon
04 Feb 2019VirgoVisible from 23:53 until 05:54
Highest at 03:31, 41° above S horizon
06 Feb 2019VirgoVisible from 22:55 until 05:53
Highest at 02:58, 45° above S horizon
08 Feb 2019LeoVisible from 21:48 until 05:50
Highest at 02:17, 51° above S horizon
10 Feb 2019LeoVisible from 20:31 until 05:48
Highest at 01:28, 59° above S horizon
12 Feb 2019LeoVisible from 19:06 until 05:46
Highest at 00:31, 66° above S horizon
14 Feb 2019CancerVisible from 18:32 until 05:12
Highest at 23:25, 73° above S horizon
16 Feb 2019CancerVisible from 18:35 until 04:27
Highest at 22:24, 79° above S horizon
18 Feb 2019GeminiVisible from 18:37 until 03:40
Highest at 21:30, 82° above S horizon
20 Feb 2019GeminiVisible from 18:39 until 02:56
Highest at 20:44, 83° above S horizon
22 Feb 2019AurigaVisible from 18:41 until 02:17
Highest at 20:06, 84° above S horizon
24 Feb 2019AurigaVisible from 18:44 until 01:43
Highest at 19:35, 84° above S horizon
26 Feb 2019AurigaVisible from 18:46 until 01:16
Highest at 19:09, 84° above S horizon
28 Feb 2019AurigaVisible from 18:48 until 00:53
Highest at 18:47, 84° above S horizon
02 Mar 2019AurigaVisible from 18:50 until 00:33
Highest at 18:50, 82° above SW horizon
04 Mar 2019AurigaVisible from 18:52 until 00:15
Highest at 18:52, 80° above SW horizon

A more detailed table of C/2018 Y1 (Iwamoto)'s position on each night is available here. A diagram of the orbit of C/2018 Y1 (Iwamoto) is available here.

On 13 February it will be visible between 19:01 and 05:23. It will become accessible around 19:01, when it rises to an altitude of 21° above your eastern horizon. It will reach its highest point in the sky at 00:14, 68° above your southern horizon. It will become inaccessible around 05:23 when it sinks below 21° above your western horizon.

Finder chart

The chart below shows the path of C/2018 Y1 (Iwamoto) 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 6 on 13 February 2019. This estimate is based on observations that the BAA has received from amateur astronomers, assuming that its current level of activity will remain constant.

This comet is not expected to be visible to the naked eye, but might be visible through bird-watching binoculars.

The comet's position on 13 February 2019 will be:

Object Right Ascension Declination Constellation Magnitude
Comet C/2018 Y1 (Iwamoto) 09h51m50s +19°26' Leo 6.4

The coordinates are given in J2000.0.

The sky on 13 February 2019
Twilight ends
Twilight begins

9-day old moon
Waxing Gibbous


9 days old

Rise Culm. Set
Mercury 07:26 12:52 18:17
Venus 04:23 09:07 13:51
Moon 11:38 18:45 00:47
Mars 09:23 16:08 22:53
Jupiter 02:56 07:35 12:14
Saturn 04:49 09:30 14:10
All times shown in EST.


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 25 Oct 2020.

Image credit

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






Color scheme