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Comets » 

Comet C/2021 S3 (PANSTARRS)

Above the horizon.  Circumpolar today
Alt: 6.34°   Az: 22.78°   Direction: North-North-East

Comet C/2021 S3 (PANSTARRS) is in the constellation of Andromeda, at a distance of 898,223,124.0 kilometers from Earth. The current Right Ascension is 23h 41m 58s and the Declination is +41° 04’ 47” (apparent coordinates). The predicted magnitude of Comet C/2021 S3 (PANSTARRS) is 17.99 (data provided by JPL Horizons).

Finder Charts

Map showing Comet C/2021 S3 (PANSTARRS) in Andromeda on June, 06 2025. Field of view: 50x30 degrees
View interactive star map
Sky map showing Comet C/2021 S3 (PANSTARRS) in Andromeda on June, 06 2025. Field of view: 15x9 degrees. View in interactive sky chart

High precision deep sky finder chart, 60 arcmin wide, showing where Comet C/2021 S3 (PANSTARRS) is right now. Click on the image to see a more detailed fullscreen tracker view.

C/2021 S3 (PANSTARRS)
RA: 23h 40m 42s
Dec: +40° 56’ 19”
Deep sky finder chart for Comet C/2021 S3 (PANSTARRS). Field of view: 60x40 arcmins. View in deep sky object tracker

Also check out Where is Comet C/2021 S3 (PANSTARRS)?, a page that provides all the information needed to find Comet C/2021 S3 (PANSTARRS) in the sky and additional links to sky charts.

Celestial Coordinates

Apparent

23h 41m 58s
+41° 04’ 47”
14h 02m 48s
13h 44m 46s

J2000

23h 40m 42s
+40° 56’ 19”

Additional Information

Andromeda
n/a
n/a
n/a
n/a
17.99

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

Today's rise, transit and set times of Comet C/2021 S3 (PANSTARRS) from Greenwich, UK (all times relative to the local timezone Europe/London):

Today Comet C/2021 S3 (PANSTARRS) is circumpolar and transits at 06:42 UTC reaching a maximum altitude of 79.6°.
  • C/2021 S3 (PANSTARRS) is above the horizon from Greenwich, UK.
  • Right now it is placed in the North-North-East direction at an altitude of 6.34° above the horizon.
  • Given its current magnitude, C/2021 S3 (PANSTARRS) is visible only through long exposure photography.
  • 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.

Distance from Earth

The distance of Comet C/2021 S3 (PANSTARRS) from Earth is currently 898,223,124.0 kilometers, equivalent to 6.0042507276 Astronomical Units. Light takes 49m 56.150s to travel from Comet C/2021 S3 (PANSTARRS) and arrive to us.

898,223,124.0
6.0042507276
49m 56.150s

The following chart shows the distance of Comet C/2021 S3 (PANSTARRS) 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.

Chart of the distance of Comet C/2021 S3 (PANSTARRS) from Earth in Astronomical Units (au)

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 S3 (PANSTARRS) from Earth is also available as a real time updated value in the Live Position and Data Tracker.

Closest Approach

Between 1 January 2000 and 31 December 2099, the closest approach of Comet C/2021 S3 (PANSTARRS) to Earth happens on Fri Mar 15 2024 at a distance of 1.297866 Astronomical Units, or 194,157,991 kilometers:

Fri Mar 15 2024
194,157,991
1.297866

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

Light Curve

The following chart is the predicted light curve (visual magnitude as a function of time) of Comet C/2021 S3 (PANSTARRS), 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.

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 20 February 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 2024-Feb-14 17:04:47
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
2h1>Orbit Visualization
Orbit Diagram of Comet C/2021 S3 (PANSTARRS)
View Comet C/2021 S3 (PANSTARRS) in the 3D Solar System Simulator

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
2025 May 30 23h 39m 25s +40° 19’ 08” 17.97 Andromeda
2025 May 31 23h 39m 47s +40° 25’ 01” 17.98 Andromeda
2025 Jun 01 23h 40m 08s +40° 30’ 53” 17.98 Andromeda
2025 Jun 02 23h 40m 28s +40° 36’ 43” 17.98 Andromeda
2025 Jun 03 23h 40m 48s +40° 42’ 33” 17.98 Andromeda
2025 Jun 04 23h 41m 07s +40° 48’ 20” 17.99 Andromeda
2025 Jun 05 23h 41m 26s +40° 54’ 07” 17.99 Andromeda
2025 Jun 06 23h 41m 43s +40° 59’ 51” 17.99 Andromeda
2025 Jun 07 23h 42m 00s +41° 05’ 34” 17.99 Andromeda
2025 Jun 08 23h 42m 16s +41° 11’ 15” 18.00 Andromeda
2025 Jun 09 23h 42m 32s +41° 16’ 55” 18.00 Andromeda
2025 Jun 10 23h 42m 46s +41° 22’ 32” 18.00 Andromeda
2025 Jun 11 23h 43m 00s +41° 28’ 08” 18.00 Andromeda
2025 Jun 12 23h 43m 13s +41° 33’ 41” 18.01 Andromeda

Additional Resources on TheSkyLive