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Comet C/2017 S7 (Lemmon)

Available Resources

Comet C/2017 S7 (Lemmon) Sky Charts and Coordinates

This is a simplified sky chart, showing where Comet C/2017 S7 (Lemmon) is now with respect to the brightest stars and constellations.

More advanced sky charts are available on TheSkyLive for this object: 1) the Online Planetarium which is interactive and allows to select dates and additional objects to visualize; and 2) the Live Position and Data Tracker which provides the highest precision position data and features deep sky imagery from the Digitized Sky Survey.

Comet C/2017 S7 (Lemmon) in Eridanus on April, 21 2019
High Precision Live Sky Chart
 = visible to the naked eye
 = binocular, brighter than 10th magnitude
= current altitude ≥ 30°   = current altitude < 30°   = below the horizon
Location: Greenwich, United Kingdom [change]
03h 37m 26s
-17° 08’ 50”

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 behvior 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.

Comet C/2017 S7 (Lemmon) Rise and Set Times

Today's Comet C/2017 S7 (Lemmon) rise, transit and set times from Greenwich, United Kingdom [change]. All times are relative to the Europe/London timezone.

Azimuth: 107.1°
Max altitude: 21.4°
Azimuth: 252.9°

Comet C/2017 S7 (Lemmon) Orbit Diagram

This 3d orbit diagram is a feature of our 3D Solar System Simulator and shows the orbit of Comet C/2017 S7 (Lemmon) with respect of the Sun and the orbits of the major planets. The position of Comet C/2017 S7 (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/2017 S7 (Lemmon)
View Comet C/2017 S7 (Lemmon) in the 3D Solar System Simulator

Comet C/2017 S7 (Lemmon) Ephemeris

The following table lists the ephemerides of Comet C/2017 S7 (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/2017 S7 (Lemmon) in our Online Planetarium at the chosen date.

Date Right AscensionR.A. DeclinationDec. MagnitudeMag Constellation
2019 Apr 14 03h 35m 27s -17° 12’ 02” 20.98 Eridanus
2019 Apr 15 03h 35m 44s -17° 11’ 27” 20.98 Eridanus
2019 Apr 16 03h 35m 58s -17° 10’ 55” 20.98 Eridanus
2019 Apr 17 03h 36m 15s -17° 10’ 27” 20.99 Eridanus
2019 Apr 18 03h 36m 30s -17° 10’ 00” 20.99 Eridanus
2019 Apr 19 03h 36m 47s -17° 09’ 36” 20.99 Eridanus
2019 Apr 20 03h 37m 03s -17° 09’ 15” 21.00 Eridanus
2019 Apr 21 03h 37m 19s -17° 08’ 57” 21.00 Eridanus
2019 Apr 22 03h 37m 36s -17° 08’ 41” 21.00 Eridanus
2019 Apr 23 03h 37m 53s -17° 08’ 29” 21.00 Eridanus
2019 Apr 24 03h 38m 09s -17° 08’ 18” 21.01 Eridanus
2019 Apr 25 03h 38m 27s -17° 08’ 12” 21.01 Eridanus
2019 Apr 26 03h 38m 44s -17° 08’ 08” 21.01 Eridanus
2019 Apr 27 03h 39m 02s -17° 08’ 07” 21.02 Eridanus

Distance of Comet C/2017 S7 (Lemmon) from Earth

The following chart shows the distance of Comet C/2017 S7 (Lemmon) from Earth as a function of time. Distance data is measured in Astronomical Units and sampled with a 2 days interval.

The reported distances might be inaccurate around the times of closest approach for objects passing extremely close to Earth. The value of the distance of C/2017 S6 (Lemmon) is also available as a real time updated value in the Live Position and Data Tracker.

Distance of Comet C/2017 S7 (Lemmon) from Earth between January 2013 and December 2100

Light Curve of Comet C/2017 S7 (Lemmon)

The following chart is the predicted light curve (visual magnitude as a function of time) of Comet C/2017 S7 (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.

Predicted magnitude of Comet C/2017 S7 (Lemmon) between January 2013 and December 2100

Comet C/2017 S7 (Lemmon) Orbital Elements

The following table lists the orbital elements of Comet C/2017 S7 (Lemmon) at epoch 27 October 2017 00:00 UTC (JD: 2458054.5). Source: JPL Small-Body Database

Element Symbol Value
Orbit eccentricity e 1.00248340
Orbit inclination i 124.22403005°
Perihelion distance q 7.61442805 AU
1,139,102,225 km
Aphelion distance Q n.a.
Semi-major axis a n.a.
Orbital period period n.a.
Date of perihelion transit Tp 2017-May-27 21:40:19
2,457,901.4030 JD
Argument of perihelion peri 187.7483789327°
Longitude of the ascending node node 262.78812565449°
Mean anomaly M 0.00088876031644228°
Mean motion n 0.00000581°/day
Closest approach to Earth* 2016-Dec-18
Distance of closest approach* 6.69809950 AU
1,002,021,425 km

* NOTE: values for the closest approach are computed for the time interval between 2013-Jan-01 and 2100-Dec-31, with a sampling interval of 1 day.