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public  Greenwich, United Kingdom Greenwich, United Kingdom  ⓘ
TimezoneEurope/London
Sunrise: 4:50 
Transit: 13:04 
Sunset: 21:18
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Comets » 

Comet C/2021 S3 (PANSTARRS)

Above the horizon.  Circumpolar today
Alt: 72.24°   Az: 108.02°   Direction: East-South-East

Comet C/2021 S3 (PANSTARRS) is in the constellation of Andromeda, at a distance of 886,475,907.0 kilometers from Earth. The current Right Ascension is 23h 44m 51s and the Declination is +43° 20’ 29” (apparent coordinates). The estimated magnitude of comet C/2021 S3 (PANSTARRS), computed using JPL Horizons's data, is 18.04).

Finder Charts

The sky charts below show, at different resolutions, the position of comet C/2021 S3 (PANSTARRS) in the sky. Click on each chart to access the interactive star map tool.

Star map showing the position of comet C/2021 S3 (PANSTARRS) in the constellation of Andromeda on F, d Y. Field of view: 50x30 degrees. View interactive star map.
Star map showing the position of comet C/2021 S3 (PANSTARRS) in the constellation of Andromeda on F, d Y. Field of view: 15x9 degrees. View in interactive star map.

The following map uses photographic imagery from the Digitized Sky Survey (DSS) to realistically visualize the precise position of comet C/2021 S3 (PANSTARRS) against the stars in the background. The horizontal size of the map measures 60 arcminutes. Click on the image to access a more detailed full-screen view.

C/2021 S3 (PANSTARRS)
RA: 23h 43m 35s
Dec: +43° 11’ 59”
Simplified high-resolution deep sky chart showing the current position of comet C/2021 S3 (PANSTARRS). Field of view: 60 x 40 arcminutes. Go to the dedicated page

Equatorial Coordinates

Apparent

23h 44m 51s
+43° 20’ 29”
22h 25m 58s
22h 10m 50s

J2000

23h 43m 35s
+43° 11’ 59”

Additional Information

Andromeda
n/a
n/a
n/a
n/a
18.04

The observed values of Magnitude, Coma Diameter and Tail Length are derived from the most recent observation recorded at the Comet Observers Database. The value of Predicted Magnitude comes from the JPL Horizons ephemerides service and, in the case of comets, might be inaccurate given the highly dynamic and unpredictable behavior of these objects. When available, please refer to the Observed Magnitude value and consider the Predicted 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.

Rise and Set Times

The following table lists today's rise, transit and set times of comet C/2021 S3 (PANSTARRS) from Greenwich, United Kingdom (all times relative to the local timezone Europe/London):

Today comet C/2021 S3 (PANSTARRS) is circumpolar and transits at 04:58 UTC reaching a maximum altitude of 81.9°.

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.

Distance from Earth

The distance of comet C/2021 S3 (PANSTARRS) from Earth is currently 886,475,907.0 kilometers, equivalent to 5.9257254321 Astronomical Units. Light takes 49m 16.965s to travel from comet C/2021 S3 (PANSTARRS) and arrive to us.

886,475,907.0
5.9257254321
49m 16.965s

The following graph shows the distance of comet C/2021 S3 (PANSTARRS) from Earth as a function of time. In the chart the distance is measured in Astronomical Units and the data is sampled with an interval of 1 day.

Chart of the distance of comet C/2021 S3 (PANSTARRS) from Earth in Astronomical Units (au)
Note: The values in this chart may not be entirely accurate around the time of closest approach for objects passing very close to Earth at high speed (e.g., Near-Earth Objects).

The value of the distance of C/2021 S3 (PANSTARRS) from Earth is also available as a real time updated value in the live position tracker.

Closest Approach to Earth

In the period between January 1, 2000 and December 31, 2099, the closest approach of comet C/2021 S3 (PANSTARRS) to Earth happened on Friday 15 March 2024 at a distance of 1.297866 Astronomical Units, or 194,157,991 kilometers:

Friday 15 March 2024
194,157,991
1.297866

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

Light Curve

The following chart shows the light curve of comet C/2021 S3 (PANSTARRS), i.e., its apparent magnitude as a function of time. The curve is calculated using the latest ephemerides provided by JPL Horizons. The magnitude data is sampled with the interval of 2 days. Because of this sampling, inaccuracies may occur for objects that have large variations of brightness over a few days. For comets, large discrepancies can arise between the calculated brightness and the observations due to their highly dynamic, and not always precisely predictable, behavior.

Chart of the magnitude of comet C/2021 S3 (PANSTARRS) as a function of time

Orbital Elements

The following table lists the orbital elements of comet C/2021 S3 (PANSTARRS) at epoch February, 20 2024 00:00 UTC (JD: 2460361.5). Source: JPL Small-Body Database

Element Symbol Value
Orbit eccentricity e 1.00024971
Orbit inclination i 58.53283988°
Perihelion distance q 1.32020916 AU
197,500,480 km
Aphelion distance Q n.a.
Semi-major axis a n.a.
Orbital period period n.a.
Date of perihelion transit Tp February 14, 2024
2,460,355.2117 JD
Argument of perihelion peri 6.8550833032033°
Longitude of the ascending node node 215.62077864739°
Mean anomaly M 1.6122560840752E-5°
Mean motion n 0.00000256°/day

Orbit Visualization

The following chart is a 3D animated visualization of the orbit of comet C/2021 S3 (PANSTARRS) relative to the other major objects in the Solar System. You can access more advanced features using our 3D Solar System Viewer.

15 Days Ephemeris

The following table lists the ephemerides of comet C/2021 S3 (PANSTARRS) computed for the past and next 7 days, with a 24 hours interval. Apparent celestial coordinates are provided.

Date Right AscensionR.A. DeclinationDec. MagnitudeMag Constellation
Jun 26 2025 23h 44m 59s +42° 47’ 09” 18.03 Andromeda
Jun 27 2025 23h 45m 00s +42° 52’ 00” 18.03 Andromeda
Jun 28 2025 23h 45m 01s +42° 56’ 49” 18.04 Andromeda
Jun 29 2025 23h 45m 01s +43° 01’ 33” 18.04 Andromeda
Jun 30 2025 23h 45m 00s +43° 06’ 14” 18.04 Andromeda
Jul 01 2025 23h 44m 58s +43° 10’ 50” 18.04 Andromeda
Jul 02 2025 23h 44m 55s +43° 15’ 23” 18.04 Andromeda
Jul 03 2025 23h 44m 52s +43° 19’ 51” 18.04 Andromeda
Jul 04 2025 23h 44m 48s +43° 24’ 15” 18.04 Andromeda
Jul 05 2025 23h 44m 43s +43° 28’ 35” 18.05 Andromeda
Jul 06 2025 23h 44m 37s +43° 32’ 50” 18.05 Andromeda
Jul 07 2025 23h 44m 30s +43° 37’ 01” 18.05 Andromeda
Jul 08 2025 23h 44m 23s +43° 41’ 07” 18.05 Andromeda
Jul 09 2025 23h 44m 14s +43° 45’ 08” 18.05 Andromeda

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