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

C/2020 R4 (ATLAS) at perigee

Dominic Ford, Editor
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Comet C/2020 R4 (ATLAS) will make its closest approach to the Earth, at a distance of 0.46 AU.

From Ashburn the 2021 apparition of C/2020 R4 (ATLAS) will progress as follows:

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02 Mar 2021 – C/2020 R4 (ATLAS) at perihelion
12 Mar 2021 – C/2020 R4 (ATLAS) reaches its brightest
23 Apr 2021 – C/2020 R4 (ATLAS) at perigee
02 Apr 2021AquilaVisible from 03:54 until 05:49
Highest at 05:49, 39° above SE horizon
04 Apr 2021AquilaVisible from 03:33 until 05:45
Highest at 05:45, 42° above SE horizon
06 Apr 2021AquilaVisible from 03:10 until 05:42
Highest at 05:42, 45° above SE horizon
08 Apr 2021AquilaVisible from 02:45 until 05:38
Highest at 05:38, 49° above SE horizon
10 Apr 2021AquilaVisible from 02:16 until 05:35
Highest at 05:35, 53° above SE horizon
12 Apr 2021AquilaVisible from 01:45 until 05:32
Highest at 05:32, 58° above SE horizon
14 Apr 2021HerculesVisible from 01:09 until 05:28
Highest at 05:28, 63° above S horizon
16 Apr 2021HerculesVisible from 00:28 until 05:25
Highest at 05:25, 67° above S horizon
18 Apr 2021HerculesVisible from 23:40 until 05:22
Highest at 05:02, 71° above S horizon
20 Apr 2021HerculesVisible from 22:50 until 05:19
Highest at 04:23, 75° above S horizon
22 Apr 2021HerculesVisible from 21:58 until 05:15
Highest at 03:40, 78° above S horizon
24 Apr 2021Corona BorealisVisible from 21:05 until 05:12
Highest at 02:53, 81° above S horizon
26 Apr 2021BootesVisible from 21:07 until 05:09
Highest at 02:06, 83° above S horizon
28 Apr 2021BootesVisible from 21:10 until 05:06
Highest at 01:20, 84° above S horizon
30 Apr 2021Canes VenaticiVisible from 21:12 until 05:03
Highest at 00:38, 84° above S horizon
02 May 2021Canes VenaticiVisible from 21:15 until 05:00
Highest at 23:56, 84° above S horizon
04 May 2021Canes VenaticiVisible from 21:17 until 04:57
Highest at 23:23, 83° above S horizon
06 May 2021Coma BerenicesVisible from 21:20 until 04:41
Highest at 22:53, 82° above S horizon
08 May 2021Coma BerenicesVisible from 21:22 until 04:12
Highest at 22:28, 81° above S horizon
10 May 2021Coma BerenicesVisible from 21:25 until 03:47
Highest at 22:05, 80° above S horizon
12 May 2021Ursa MajorVisible from 21:27 until 03:24
Highest at 21:45, 79° above S horizon

A more detailed table of C/2020 R4 (ATLAS)'s position on each night is available here. A diagram of the orbit of C/2020 R4 (ATLAS) is available here.

Finder chart

The chart below shows the path of C/2020 R4 (ATLAS) 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 7 at perigee. 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 at perihelion will be:

Object Right Ascension Declination Constellation Magnitude
Comet C/2020 R4 (ATLAS) 16h21m50s +27°49' 7.3

The coordinates are given in J2000.0.

The sky on 23 April 2021
Sunrise
06:21
Sunset
19:54
Twilight ends
21:32
Twilight begins
04:43

11-day old moon
Waxing Gibbous

83%

11 days old

Planets
Rise Culm. Set
Mercury 06:36 13:28 20:20
Venus 06:46 13:37 20:28
Moon 16:07 22:38 04:38
Mars 09:30 17:02 00:35
Jupiter 03:42 09:01 14:20
Saturn 03:01 08:04 13:08
All times shown in EDT.

Source

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 03 Feb 2021.

Image credit

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

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77.49°W
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