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Comet C/2021 D1 (SWAN)

Comet C/2021 D1 (SWAN) is currently in the constellation of Perseus. The current Right Ascension of Comet C/2021 D1 (SWAN) is 03h 41m 36s and the Declination is +34° 04’ 02” (topocentric coordinates computed for the selected location: Greenwich, United Kingdom [change]). The current estimated magnitude of Comet C/2021 D1 (SWAN) is 15.38 (JPL) while the latest observed magnitude is 11.7 (COBS).

Summary of key facts about Comet C/2021 D1 (SWAN) [tip: you can also create a Quick Access page for this data if you access it frequently and would like to have a simpler view]:

03h 41m 36s
+34° 04’ 02”
  • C/2021 D1 (SWAN) is above the horizon from Greenwich, United Kingdom [change].
  • It is visible looking in the West-North-West direction at an altitude of 32° above the horizon.
  • Given its current magnitude, C/2021 D1 (SWAN) is visible with the help of a telescope havng an aperture of 8 inches (200mm) or more.
  • See also C/2021 D1 (SWAN) rise and set times.
  • Go to interactive sky chart

If you need to access this information frequently for your observations, you can create a simple customized Quick Access page, so that you can easily bookmark it in your browser favorites or add a shortcut to your mobile phones' home screen.

Additional information about Comet C/2021 D1 (SWAN) available on TheSkyLive:

Available Resources

Comet C/2021 D1 (SWAN) Position and Finder Charts

Below we provide Comet C/2021 D1 (SWAN) finder charts showing where the object is right now in the sky with respect to the brightest stars. The first finder chart has a field of view of 50 degrees, while the second one has a field of view of 10 degrees. Click on each finder chart to access a full screen interactive Online Planetarium.

Map showing Comet C/2021 D1 (SWAN) in Perseus on April, 16 2021
Field of view: 50x30 degrees
View fullscreen
Map showing Comet C/2021 D1 (SWAN) in Perseus on April, 16 2021
Field of view: 10x6 degrees
View fullscreen
 = visible to the naked eye
 = binocular, brighter than 10th magnitude
= current altitude ≥ 30°   = current altitude < 30°   = below the horizon
Location: Greenwich, United Kingdom [change]

Higher precision deep sky finder chart, 60 arcmin wide, showing where Comet C/2021 D1 (SWAN) is right now. Click on the image to see a more detailed fullscreen tracker view.

C/2021 D1 (SWAN)
RA: 03h 41m 36s
Dec: +34° 04’ 02”
Deep sky finder chart for Comet C/2021 D1 (SWAN)
Field of view: 60x40 arcmins
View fullscreen

Also check out Where is Comet C/2021 D1 (SWAN)?, a page that provides all the information needed to find Comet C/2021 D1 (SWAN) in the sky and additional links to sky charts.

Comet C/2021 D1 (SWAN) Distance from Earth

The distance of Comet C/2021 D1 (SWAN) from Earth is currently 281,507,683 kilometers, equivalent to 1.881763 Astronomical Units. Light takes 15 minutes and 39.0086 seconds to travel from Comet C/2021 D1 (SWAN) and arrive to us.

15 minutes and 39.0086 seconds

The following chart shows the distance of Comet C/2021 D1 (SWAN) from Earth as a function of time. In the chart the distance data is measured in Astronomical Units and sampled with an interval of 1 day.

Distance of Comet C/2021 D1 (SWAN) from Earth between January 2014 and January 2100

The value of the reported distance might be somewhat inaccurate around the times of closest approach for objects passing extremely close to Earth. The value of the distance of C/2021 D1 (SWAN) from Earth is also available as a real time updated value in the Live Position and Data Tracker.

Closest approach of Comet C/2021 D1 (SWAN) to Earth

Between January 2014 and January 2100, the closest approach of Comet C/2021 D1 (SWAN) to Earth happens on Mon Mar 15 2021 at a distance of 1.676263 Astronomical Units, or 250,765,345 kilometers:

Mon Mar 15 2021

NOTE: values for the closest approach are computed with a sampling interval of 1 day.

Comet C/2021 D1 (SWAN) brightness

The current visual magnitude of Comet C/2021 D1 (SWAN) is 15.38.


The observed magnitude and coma diameter values are derived from the Comet Observers Database by averaging the values reported in recent observations (more recent than 4 days), when available. The Estimated Magnitude comes from the JPL Horizons ephemerides service and might be inaccurate given the highly dynamic and unpredictable behavior of comets. When available, please refer to the Observed Magnitude value and consider the Estimated Magnitude as a directional indication. We acknowledge with thanks the comet observations from the COBS Comet Observation Database contributed by observers worldwide and used in this table to report recent comet observations.

The following chart is the predicted light curve (visual magnitude as a function of time) of Comet C/2021 D1 (SWAN), according to the most recent ephemerides data. Magnitude data is sampled with a 2 days interval and there might be inaccuracies for objects changing brightness very rapidly during the course of a few days. For comets there could be large discrepancies between the observed and predicted brightness because of their highly dynamic behaviour.

Predicted magnitude of Comet C/2021 D1 (SWAN) between January 2014 and January 2100

Comet C/2021 D1 (SWAN) rise and set times

Location: Greenwich, United Kingdom [change]
Latitude: 51° 28’ 47” N
Longitude: 0° 00’ 00” E
Timezone: Europe/London

Today's Comet C/2021 D1 (SWAN) rise, transit and set times from Greenwich, United Kingdom [change] are the following (all times relative to the local timezone Europe/London):

Azimuth: 56.0°
Max altitude: 72.6°
Azimuth: 304.1°

The rise and set times are defined as the time at which the upper limb of Comet C/2021 D1 (SWAN) touches the horizon, considering the effect of the atmospheric refraction. As the atmospheric conditions cannot be modeled precisely the times reported here should be considered correct with an approximation of few minutes.

Comet C/2021 D1 (SWAN) Orbital Elements

The following table lists the orbital elements of Comet C/2021 D1 (SWAN) at epoch 01 March 2021 00:00 UTC (JD: 2459275.5). Source: JPL Small-Body Database

Element Symbol Value
Orbit eccentricity e 0.98242820
Orbit inclination i 31.46529325°
Perihelion distance q 0.90089697 AU
134,772,268 km
Aphelion distance Q 101.63804670 AU
15,204,835,399 km
Semi-major axis a 51.26947183 AU
7,669,803,834 km
Orbital period period 367.1100 years
134,087.0055 days
Date of perihelion transit Tp 2021-Feb-27 09:56:32
2,459,272.9143 JD
Next perihelion transit 2388-Apr-11 10:04
2,593,359.9198 JD
Argument of perihelion peri 71.957134719373°
Longitude of the ascending node node 311.24246585021°
Mean anomaly M 0.0069422296785664°
Mean motion n 0.00268482°/day

Visualization of Comet C/2021 D1 (SWAN) Orbit

This 3d orbit diagram is a feature of our 3D Solar System Simulator and shows the orbit of Comet C/2021 D1 (SWAN) with respect of the Sun and the orbits of the major planets. The position of Comet C/2021 D1 (SWAN) and the planets along their orbits in this diagram accurately represents the current configuration of the objects in the Solar System. This is an experimental feature and it requires a WebGL enabled browser. Please provide us feedback!

Orbit Diagram of Comet C/2021 D1 (SWAN)
View Comet C/2021 D1 (SWAN) in the 3D Solar System Simulator

Comet C/2021 D1 (SWAN) 15 Days Ephemeris

The following table lists the ephemerides of Comet C/2021 D1 (SWAN) computed for the past and next 7 days, with a 24 hours interval. Click on each row of the table to locate Comet C/2021 D1 (SWAN) in our Online Planetarium at the chosen date.

Date Right AscensionR.A. DeclinationDec. MagnitudeMag Constellation
2021 Apr 09 02h 59m 21s +32° 59’ 26” 14.97 Perseus
2021 Apr 10 03h 04m 53s +33° 10’ 51” 15.03 Perseus
2021 Apr 11 03h 10m 23s +33° 21’ 19” 15.08 Perseus
2021 Apr 12 03h 15m 51s +33° 30’ 51” 15.13 Perseus
2021 Apr 13 03h 21m 18s +33° 39’ 26” 15.18 Perseus
2021 Apr 14 03h 26m 41s +33° 47’ 08” 15.23 Perseus
2021 Apr 15 03h 32m 03s +33° 53’ 57” 15.29 Perseus
2021 Apr 16 03h 37m 23s +33° 59’ 53” 15.34 Perseus
2021 Apr 17 03h 42m 38s +34° 05’ 00” 15.39 Perseus
2021 Apr 18 03h 47m 53s +34° 09’ 19” 15.45 Perseus
2021 Apr 19 03h 53m 03s +34° 12’ 48” 15.50 Perseus
2021 Apr 20 03h 58m 10s +34° 15’ 33” 15.55 Perseus
2021 Apr 21 04h 03m 15s +34° 17’ 32” 15.61 Perseus
2021 Apr 22 04h 08m 17s +34° 18’ 50” 15.66 Perseus