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public LocationGreenwich, UK
Sunrise: 4:59 
Transit: 13:04 
Sunset: 21:08
sunny   (Daytime)   What's Visible Now?
Comets » 

Comet 123P/West-Hartley

Below the horizon.  Rise: 1:06 | Tran: 6:56 | Set: 12:46
Alt: -24.19°   Az: 301.23°   Direction: West-North-West

Comet 123P/West-Hartley is in the constellation of Cetus, at a distance of 702,468,507.0 kilometers from Earth. The current Right Ascension is 01h 28m 30s and the Declination is -01° 29’ 21” (apparent coordinates). The predicted magnitude of Comet 123P/West-Hartley is 23.90 (data provided by JPL Horizons).

Finder chart of 123P/West-Hartley in Cetus on July,14 2024
Map showing Comet 123P/West-Hartley in Cetus on July, 14 2024. Field of view: 50x30 degrees
View interactive star map

Celestial Coordinates


01h 28m 30s
-01° 29’ 21”
08h 34m 50s
10h 03m 20s


01h 27m 15s
-01° 36’ 57”

Additional Information


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 123P/West-Hartley from Greenwich, UK (all times relative to the local timezone Europe/London):

Azimuth: 91.6°
Max altitude: 36.9°
Azimuth: 268.4°
  • 123P/West-Hartley is below the horizon from Greenwich, UK.
  • 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.

Finder Charts

Finder chart of 123P/West-Hartley
Sky map showing Comet 123P/West-Hartley in Cetus on July, 14 2024. Field of view: 10x6 degrees. View in interactive sky chart

High 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: 01h 27m 15s
Dec: -01° 36’ 57”
Deep sky finder chart for Comet 123P/West-Hartley. Field of view: 60x40 arcmins. View in deep sky object tracker

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.

Distance from Earth

The distance of Comet 123P/West-Hartley from Earth is currently 702,468,507.0 kilometers, equivalent to 4.6957119357 Astronomical Units. Light takes 39m 3.183s to travel from Comet 123P/West-Hartley and arrive to us.

39m 3.183s

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

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.

Light Curve

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

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

Orbit Visualization

Orbit Diagram of Comet 123P/West-Hartley
View Comet 123P/West-Hartley in the 3D Solar System Simulator

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. Apparent celestial coordinates are provided.

Date Right AscensionR.A. DeclinationDec. MagnitudeMag Constellation
2024 Jul 07 01h 26m 05s -01° 35’ 45” 24.00 Cetus
2024 Jul 08 01h 26m 26s -01° 34’ 40” 23.99 Cetus
2024 Jul 09 01h 26m 47s -01° 33’ 41” 23.97 Cetus
2024 Jul 10 01h 27m 07s -01° 32’ 45” 23.96 Cetus
2024 Jul 11 01h 27m 26s -01° 31’ 53” 23.95 Cetus
2024 Jul 12 01h 27m 45s -01° 31’ 05” 23.94 Cetus
2024 Jul 13 01h 28m 03s -01° 30’ 22” 23.92 Cetus
2024 Jul 14 01h 28m 20s -01° 29’ 43” 23.91 Cetus
2024 Jul 15 01h 28m 37s -01° 29’ 08” 23.90 Cetus
2024 Jul 16 01h 28m 54s -01° 28’ 37” 23.89 Cetus
2024 Jul 17 01h 29m 09s -01° 28’ 11” 23.87 Cetus
2024 Jul 18 01h 29m 24s -01° 27’ 50” 23.86 Cetus
2024 Jul 19 01h 29m 38s -01° 27’ 32” 23.85 Cetus
2024 Jul 20 01h 29m 52s -01° 27’ 19” 23.84 Cetus

Additional Resources