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public Observing fromLocation: Greenwich, United Kingdom edit_location_alt
north SunriseRise: 6:43  
clear_day Transit: 12:51  
SunsetSet: 18:59 south
sunny DaytimeWhat's Visible Now
Comets » 

Comet C/2021 T4 (Lemmon)

Altitude: 17.8°   Azimuth: 145.9°   Direction: South-East

Comet C/2021 T4 (Lemmon) is currently in the constellation of Libra. The current Right Ascension of Comet C/2021 T4 (Lemmon) is 14h 51m 36s and the Declination is -14° 35’ 15” (topocentric coordinates computed for the selected location: Greenwich, United Kingdom edit_location_alt). The current estimated magnitude of Comet C/2021 T4 (Lemmon) is 12.86 (JPL).

14h 51m 36s
-14° 35’ 15”

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.

Today's rise, transit and set times of Comet C/2021 T4 (Lemmon) from Greenwich, United Kingdom edit_location_alt (all times relative to the local timezone Europe/London):

Azimuth: 104.6°
Max altitude: 23.9°
Azimuth: 255.5°
  • C/2021 T4 (Lemmon) is above the horizon from Greenwich, United Kingdom edit_location_alt.
  • Right now it is placed in the South-East direction at an altitude of 18° above the horizon.
  • Given its current magnitude, C/2021 T4 (Lemmon) is visible with the help of a telescope having an aperture of 10 inches (250mm) or more.
  • 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.

Available Resources

Comet C/2021 T4 (Lemmon) Position and Finder Charts

Below we provide Comet C/2021 T4 (Lemmon) 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.

Finder chart of C/2021 T4 (Lemmon) in Libra on September,21 2023
Map showing Comet C/2021 T4 (Lemmon) in Libra on September, 21 2023
Field of view: 50x30 degrees
View fullscreen
Finder chart of C/2021 T4 (Lemmon)
Map showing Comet C/2021 T4 (Lemmon) in Libra on September, 21 2023
Field of view: 10x6 degrees
View fullscreen

Higher precision deep sky finder chart, 60 arcmin wide, showing where Comet C/2021 T4 (Lemmon) is right now. Click on the image to see a more detailed fullscreen tracker view.

C/2021 T4 (Lemmon)
RA: 14h 51m 36s
Dec: -14° 35’ 15”
Deep sky finder chart for Comet C/2021 T4 (Lemmon)
Field of view: 60x40 arcmins
View fullscreen

Also check out Where is Comet C/2021 T4 (Lemmon)?, a page that provides all the information needed to find Comet C/2021 T4 (Lemmon) in the sky and additional links to sky charts.

Comet C/2021 T4 (Lemmon) Distance from Earth

The distance of Comet C/2021 T4 (Lemmon) from Earth is currently 324,091,375 kilometers, equivalent to 2.166417 Astronomical Units. Light takes 18 minutes and 1.0525 seconds to travel from Comet C/2021 T4 (Lemmon) and arrive to us.

18 minutes and 1.0525 seconds

The following chart shows the distance of Comet C/2021 T4 (Lemmon) 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 T4 (Lemmon) 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 T4 (Lemmon) from Earth is also available as a real time updated value in the Live Position and Data Tracker.

Closest Approach of Comet C/2021 T4 (Lemmon) to Earth

Between 1 January 2000 and 31 December 2099, the closest approach of Comet C/2021 T4 (Lemmon) to Earth happens on Fri Jul 21 2023 at a distance of 0.541534 Astronomical Units, or 81,012,307 kilometers:

Fri Jul 21 2023

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

Comet C/2021 T4 (Lemmon) Brightness and Light Curve

The following chart is the predicted light curve (visual magnitude as a function of time) of Comet C/2021 T4 (Lemmon), 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 T4 (Lemmon) as a function of time

Comet C/2021 T4 (Lemmon) Orbital Elements

The following table lists the orbital elements of Comet C/2021 T4 (Lemmon) at epoch 19 August 2022 00:00 UTC (JD: 2459811.5). Source: JPL Small-Body Database

Element Symbol Value
Orbit eccentricity e 0.99996874
Orbit inclination i 160.75778068°
Perihelion distance q 1.48199298 AU
221,702,995 km
Aphelion distance Q 94,810.21049579 AU
14,183,405,639,233 km
Semi-major axis a 47,405.84624439 AU
7,091,813,671,114 km
Orbital period period 10,321,814.6864 years
3,770,042,814.1990 days
Date of perihelion transit Tp 2023-Jul-31 12:33:47
2,460,157.0235 JD
Next perihelion transit 2023-Jul-31 12:33
3,772,502,971.2225 JD
Argument of perihelion peri 329.7808734849°
Longitude of the ascending node node 257.8014092137°
Mean anomaly M 359.99996700609°
Mean motion n 0.00000010°/day

Visualization of Comet C/2021 T4 (Lemmon) Orbit

This 3d orbit diagram is a feature of our 3D Solar System Simulator and shows the orbit of Comet C/2021 T4 (Lemmon) with respect of the Sun and the orbits of the major planets. The position of Comet C/2021 T4 (Lemmon) 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 T4 (Lemmon)
View Comet C/2021 T4 (Lemmon) in the 3D Solar System Simulator

Comet C/2021 T4 (Lemmon) 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. Click on each row of the table to locate Comet C/2021 T4 (Lemmon) in our Online Planetarium at the chosen date.

Date Right AscensionR.A. DeclinationDec. MagnitudeMag Constellation
2023 Sep 14 14h 51m 20s -15° 46’ 59” 12.57 Libra
2023 Sep 15 14h 51m 19s -15° 36’ 20” 12.61 Libra
2023 Sep 16 14h 51m 19s -15° 26’ 03” 12.65 Libra
2023 Sep 17 14h 51m 19s -15° 16’ 09” 12.69 Libra
2023 Sep 18 14h 51m 20s -15° 06’ 33” 12.73 Libra
2023 Sep 19 14h 51m 24s -14° 57’ 18” 12.77 Libra
2023 Sep 20 14h 51m 28s -14° 48’ 19” 12.80 Libra
2023 Sep 21 14h 51m 33s -14° 39’ 38” 12.84 Libra
2023 Sep 22 14h 51m 38s -14° 31’ 14” 12.88 Libra
2023 Sep 23 14h 51m 45s -14° 23’ 04” 12.91 Libra
2023 Sep 24 14h 51m 52s -14° 15’ 10” 12.95 Libra
2023 Sep 25 14h 52m 00s -14° 07’ 29” 12.98 Libra
2023 Sep 26 14h 52m 09s -14° 00’ 02” 13.02 Libra
2023 Sep 27 14h 52m 19s -13° 52’ 48” 13.05 Libra