14,501 days ago
Dominic Ford, Editor
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Comet 73P/Schwassmann-Wachmann is forecast to reach the brightest point in its 1985 apparition on 4 May. At that time, it will lie at a distance of 0.98 AU from the Sun, and at a distance of 0.11 AU from the Earth.
From Cambridge on 4 May it will be visible in the dawn sky, rising at 23:42 (EST) and reaching an altitude of 47° above the eastern horizon before fading from view as dawn breaks at around 04:19.
The events that comprise the 1985 apparition of 73P/Schwassmann-Wachmann are as follows:
| Date | Event |
| 01 May 1985 | Comet 73P/Schwassmann-Wachmann passes perigee |
| 04 May 1985 | Comet 73P/Schwassmann-Wachmann reaches peak brightness |
| 01 Jun 1985 | Comet 73P/Schwassmann-Wachmann passes perihelion |
The table below lists the times when 73P/Schwassmann-Wachmann will be visible from Cambridge day-by-day through its apparition:
| Date | Constellation | Comet visibility |
| 13 Apr 1985 | Corona Borealis | Visible from 20:10 until 03:56 Highest at 01:52, 76° above S horizon |
| 15 Apr 1985 | Corona Borealis | Visible from 20:10 until 03:52 Highest at 01:57, 78° above S horizon |
| 17 Apr 1985 | Corona Borealis | Visible from 20:12 until 03:48 Highest at 02:04, 79° above S horizon |
| 19 Apr 1985 | Corona Borealis | Visible from 20:17 until 03:45 Highest at 02:14, 80° above S horizon |
| 21 Apr 1985 | Hercules | Visible from 20:22 until 03:41 Highest at 02:28, 82° above S horizon |
| 23 Apr 1985 | Hercules | Visible from 20:33 until 03:37 Highest at 02:47, 83° above S horizon |
| 25 Apr 1985 | Hercules | Visible from 20:51 until 03:34 Highest at 03:13, 84° above S horizon |
| 27 Apr 1985 | Lyra | Visible from 21:19 until 03:30 Highest at 03:30, 84° above SE horizon |
| 29 Apr 1985 | Lyra | Visible from 22:58 until 04:27 Highest at 04:27, 78° above SE horizon |
| 01 May 1985 | Cygnus | Visible from 23:47 until 04:23 Highest at 04:23, 69° above E horizon |
| 03 May 1985 | Cygnus | Visible from 00:41 until 04:20 Highest at 04:20, 59° above E horizon |
| 05 May 1985 | Pegasus | Visible from 01:35 until 04:17 Highest at 04:17, 49° above E horizon |
| 07 May 1985 | Pegasus | Visible from 02:23 until 04:14 Highest at 04:14, 40° above E horizon |
| 09 May 1985 | Pegasus | Visible from 03:04 until 04:11 Highest at 04:11, 33° above E horizon |
| 11 May 1985 | Pegasus | Visible from 03:38 until 04:08 Highest at 04:08, 26° above E horizon |
| 13 May 1985 | Pegasus | Not observable |
| 15 May 1985 | Pisces | Not observable |
| 17 May 1985 | Pisces | Not observable |
| 19 May 1985 | Pisces | Not observable |
| 21 May 1985 | Pisces | Not observable |
| 23 May 1985 | Cetus | Not observable |
A more detailed table of 73P/Schwassmann-Wachmann's position on each night is available here. A diagram of the orbit of 73P/Schwassmann-Wachmann is available here.
Finder chart
The chart below shows the path of 73P/Schwassmann-Wachmann 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 73P/Schwassmann-Wachmann is currently available.
The comet's position on 4 May 1985 will be:
| Object | Right Ascension | Declination | Constellation | Magnitude |
| Comet 73P/Schwassmann-Wachmann | 21h28m30s | 24°20'N | Vulpecula | 6.0 |
The coordinates are given in J2000.0.
The sky on 15 Jan 2025
| The sky on 15 January 2025 | ||||||||||||||||||||||||||||||||||
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95% 16 days old |
All times shown in EST.
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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 14 Jan 2025.
Image credit
© Andy Roberts 1997. Pictured comet is C/1995 O1 Hale-Bopp.