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public  Gaotang, China Gaotang, China  ⓘ
TimezoneAsia/Shanghai
Sunrise: 5:21 
Transit: 12:13 
Sunset: 19:06
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Comets » 

Comet C/2021 T4 (Lemmon)

Below the horizon.  Rise: 9:20 | Tran: 16:16 | Set: 23:12
Alt: -24.86°   Az: 321.43°   Direction: North-West

Comet C/2021 T4 (Lemmon) is in the constellation of Leo Minor, at a distance of 1,203,223,046.0 kilometers from Earth. The current Right Ascension is 10h 53m 11s and the Declination is +26° 19’ 56” (apparent coordinates). The estimated magnitude of comet C/2021 T4 (Lemmon), computed using JPL Horizons's data, is 20.87).

Finder Charts

The sky charts below show, at different resolutions, the position of comet C/2021 T4 (Lemmon) in the sky. Click on each chart to access the interactive star map tool.

Star map showing the position of comet C/2021 T4 (Lemmon) in the constellation of Leo Minor on F, d Y. Field of view: 50x30 degrees. View interactive star map.
Star map showing the position of comet C/2021 T4 (Lemmon) in the constellation of Leo Minor 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 T4 (Lemmon) 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 T4 (Lemmon)
RA: 10h 51m 48s
Dec: +26° 28’ 06”
Simplified high-resolution deep sky chart showing the current position of comet C/2021 T4 (Lemmon). Field of view: 60 x 40 arcminutes. Go to the dedicated page

Equatorial Coordinates

Apparent

10h 53m 11s
+26° 19’ 56”
09h 23m 27s
20h 16m 39s

J2000

10h 51m 48s
+26° 28’ 06”

Additional Information

Leo Minor
n/a
n/a
n/a
n/a
20.87

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 T4 (Lemmon) from Gaotang, China (all times relative to the local timezone Asia/Shanghai):

Azimuth: 63.6°
Max altitude: 89.5°
Azimuth: 296.3°

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 T4 (Lemmon) from Earth is currently 1,203,223,046.0 kilometers, equivalent to 8.0430492785 Astronomical Units. Light takes 1h 6m 53.520s to travel from comet C/2021 T4 (Lemmon) and arrive to us.

1,203,223,046.0
8.0430492785
1h 6m 53.520s

The following graph shows the distance of comet C/2021 T4 (Lemmon) 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 T4 (Lemmon) 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 T4 (Lemmon) 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 T4 (Lemmon) to Earth happened on Friday 21 July 2023 at a distance of 0.541555 Astronomical Units, or 81,015,514 kilometers:

Friday 21 July 2023
81,015,514
0.541555

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 T4 (Lemmon), 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 T4 (Lemmon) as a function of time

Orbital Elements

The following table lists the orbital elements of comet C/2021 T4 (Lemmon) at epoch April, 13 2023 00:00 UTC (JD: 2460048.5). Source: JPL Small-Body Database

Element Symbol Value
Orbit eccentricity e 0.99991819
Orbit inclination i 160.77740884°
Perihelion distance q 1.48329798 AU
221,898,219 km
Aphelion distance Q 36,262.09015781 AU
5,424,731,485,618 km
Semi-major axis a 18,131.78672789 AU
2,712,476,691,919 km
Orbital period period 2,441,569.5804 years
891,783,289.2347 days
Date of perihelion transit Tp July 31, 2023
2,460,157.0270 JD
Next perihelion transit April 18, 2443643
894,243,446.2617 JD
Argument of perihelion peri 329.81392999632°
Longitude of the ascending node node 257.88231220148°
Mean anomaly M 359.99995618921°
Mean motion n 0.00000040°/day

Orbit Visualization

The following chart is a 3D animated visualization of the orbit of comet C/2021 T4 (Lemmon) 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 T4 (Lemmon) 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 10h 52m 09s +26° 42’ 05” 20.80 Leo Minor
Jun 27 2025 10h 52m 16s +26° 39’ 15” 20.81 Leo Minor
Jun 28 2025 10h 52m 23s +26° 36’ 24” 20.82 Leo Minor
Jun 29 2025 10h 52m 30s +26° 33’ 33” 20.83 Leo Minor
Jun 30 2025 10h 52m 38s +26° 30’ 41” 20.83 Leo Minor
Jul 01 2025 10h 52m 46s +26° 27’ 49” 20.84 Leo Minor
Jul 02 2025 10h 52m 55s +26° 24’ 57” 20.85 Leo Minor
Jul 03 2025 10h 53m 04s +26° 22’ 04” 20.86 Leo Minor
Jul 04 2025 10h 53m 14s +26° 19’ 11” 20.87 Leo Minor
Jul 05 2025 10h 53m 24s +26° 16’ 17” 20.87 Leo Minor
Jul 06 2025 10h 53m 34s +26° 13’ 24” 20.88 Leo Minor
Jul 07 2025 10h 53m 44s +26° 10’ 31” 20.89 Leo Minor
Jul 08 2025 10h 53m 55s +26° 07’ 38” 20.90 Leo Minor
Jul 09 2025 10h 54m 07s +26° 04’ 44” 20.90 Leo Minor

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