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🌎  Observing from: Greenwich, United Kingdom [change]
🌅 Sunrise: 5:50  ☀️ Transit: 12:04  🌅 Sunset: 18:19

Comet 123P/West-Hartley

Comet 123P/West-Hartley is currently in the constellation of Aquarius. The current Right Ascension of Comet 123P/West-Hartley is 23h 11m 10s and the Declination is -18° 36’ 45” (topocentric coordinates computed for the selected location: Greenwich, United Kingdom [change]). The current estimated magnitude of Comet 123P/West-Hartley is 25.68 (JPL).

23h 11m 10s
-18° 36’ 45”

Today's rise, transit and set times of Comet 123P/West-Hartley from Greenwich, United Kingdom [change] (all times relative to the local timezone Europe/London):

Azimuth: 108.6°
Max altitude: 19.9°
Azimuth: 251.4°
  • 123P/West-Hartley is below the horizon from Greenwich, United Kingdom [change].
  • Given its current magnitude, 123P/West-Hartley 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.

Available Resources

Comet 123P/West-Hartley Position and Finder Charts

Below we provide Comet 123P/West-Hartley 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 123P/West-Hartley in Aquarius on March, 26 2023
Field of view: 50x30 degrees
View fullscreen
Map showing Comet 123P/West-Hartley in Aquarius on March, 26 2023
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 123P/West-Hartley is right now. Click on the image to see a more detailed fullscreen tracker view.

RA: 23h 11m 10s
Dec: -18° 36’ 45”
Deep sky finder chart for Comet 123P/West-Hartley
Field of view: 60x40 arcmins
View fullscreen

Also check out Where is Comet 123P/West-Hartley?, a page that provides all the information needed to find Comet 123P/West-Hartley in the sky and additional links to sky charts.

Comet 123P/West-Hartley Distance from Earth

The distance of Comet 123P/West-Hartley from Earth is currently 965,374,421 kilometers, equivalent to 6.453129 Astronomical Units. Light takes 53 minutes and 40.1425 seconds to travel from Comet 123P/West-Hartley and arrive to us.

53 minutes and 40.1425 seconds

The following chart shows the distance of Comet 123P/West-Hartley 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 123P/West-Hartley 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 123P/West-Hartley from Earth is also available as a real time updated value in the Live Position and Data Tracker.

Closest Approach of Comet 123P/West-Hartley to Earth

Between 1 January 2013 and 30 December 2100, the closest approach of Comet 123P/West-Hartley to Earth happens on Thu Feb 28 2019 at a distance of 1.199581 Astronomical Units, or 179,454,775 kilometers:

Thu Feb 28 2019

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

Comet 123P/West-Hartley Brightness

The current visual magnitude of Comet 123P/West-Hartley is 25.68.


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 123P/West-Hartley, 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 123P/West-Hartley as a function of time

Comet 123P/West-Hartley Orbital Elements

The following table lists the orbital elements of Comet 123P/West-Hartley at epoch 18 September 2015 00:00 UTC (JD: 2457284.5). Source: JPL Small-Body Database

Element Symbol Value
Orbit eccentricity e 0.44927022
Orbit inclination i 15.35454558°
Perihelion distance q 2.12610687 AU
318,061,062 km
Aphelion distance Q 5.59494602 AU
836,992,012 km
Semi-major axis a 3.86052645 AU
577,526,537 km
Orbital period period 7.5854 years
2,770.5642 days
Date of perihelion transit Tp 2019-Feb-04 08:09:24
2,458,518.8399 JD
Next perihelion transit 2026-Sep-05 21:41
2,461,289.4041 JD
Argument of perihelion peri 102.91844683507°
Longitude of the ascending node node 46.527373044969°
Mean anomaly M 199.61304892378°
Mean motion n 0.12993743°/day

Visualization of Comet 123P/West-Hartley Orbit

This 3d orbit diagram is a feature of our 3D Solar System Simulator and shows the orbit of Comet 123P/West-Hartley with respect of the Sun and the orbits of the major planets. The position of Comet 123P/West-Hartley 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 123P/West-Hartley
View Comet 123P/West-Hartley in the 3D Solar System Simulator

Comet 123P/West-Hartley 15 Days Ephemeris

The following table lists the ephemerides of Comet 123P/West-Hartley computed for the past and next 7 days, with a 24 hours interval. Click on each row of the table to locate Comet 123P/West-Hartley in our Online Planetarium at the chosen date.

Date Right AscensionR.A. DeclinationDec. MagnitudeMag Constellation
2023 Mar 19 23h 05m 53s -19° 06’ 37” 25.70 Aquarius
2023 Mar 20 23h 06m 38s -19° 02’ 16” 25.70 Aquarius
2023 Mar 21 23h 07m 24s -18° 57’ 56” 25.70 Aquarius
2023 Mar 22 23h 08m 09s -18° 53’ 38” 25.69 Aquarius
2023 Mar 23 23h 08m 54s -18° 49’ 21” 25.69 Aquarius
2023 Mar 24 23h 09m 39s -18° 45’ 06” 25.69 Aquarius
2023 Mar 25 23h 10m 24s -18° 40’ 54” 25.69 Aquarius
2023 Mar 26 23h 11m 09s -18° 36’ 45” 25.68 Aquarius
2023 Mar 27 23h 11m 54s -18° 32’ 35” 25.68 Aquarius
2023 Mar 28 23h 12m 39s -18° 28’ 30” 25.68 Aquarius
2023 Mar 29 23h 13m 23s -18° 24’ 25” 25.67 Aquarius
2023 Mar 30 23h 14m 08s -18° 20’ 23” 25.67 Aquarius
2023 Mar 31 23h 14m 52s -18° 16’ 24” 25.67 Aquarius
2023 Apr 01 23h 15m 36s -18° 12’ 26” 25.66 Aquarius