new icn messageflickr-free-ic3d pan white
74P/Smirnova-Chernykh 2018-Apr-20 04:12:12 UTC | by cbellh47
Back to photostream

74P/Smirnova-Chernykh 2018-Apr-20 04:12:12 UTC


2018-Apr-20 04:12:12 UTC

stack 4 x 600 secs

Sky motion 0.19 "/min PA 264.5 deg

Magnitude 16.5 R aperture radius 10.25 arc sec UCAC4

Coma 29" x 22" extended pa 290 deg

Tail 1.6 arc minutes PA 290 deg

Charles Bell H47 Vicksburg

0.3-m Schmidt-Cassegrain + CCD + R filter


Ephemeris data:

t - T = +83.37492 days

Delta = 2.760 AU

r = 3.549 AU

Elongation = 135.7 deg

Phase = 11.4 deg

PsAng = 22.1 deg

PsAMV = 293.0 deg

PlAng = -1.deg

Constellation: Leo

The positiion angle of the tail is near the PA of the negative velocity vector indicating heavier dust particles giving only a small curvature.


Comet 74P was discovered by T. M. Smirnova N. S. Chernykh, Crimean Astrophysical Observatory in March 1975 at magnitude 15 as a diffuse condensation with no tail on photographic plates exposed on March 4 and 16, 1975 (IAUC 1764).


Comet 74P peaked in brightness near its perihelion on 2018-Jan-26 at 3.536 AU. It returns approximately every 8.48 years orbiting between Mars and Jupiter. Its nuclear radius is given as 2.23 km in Comets II. Because its Jupiter Tisserand value is slightly above 3, this comet is classified dynamically as an Encke type comet T_jup = 3.007 a = 4.16 AU. An Encke-type comet, as defined by Levison and Duncan (TJupiter > 3; a < aJupiter). This comet experienced close enounters with Jupiter in Oct 1955 and 1963 and is expected to pass close to Jupiter again in 2021 and 2030.


Prior to October 28, 1955, the object was orbiting outside of the orbit of Jupiter. After the close approach on 1955-Oct-28 at 0.246 au, the object began orbiting inside the ellipse of Jupiter, i.e. capture of a centaur. The comet was discovered within a subsequent revolution in 1975 after its period and perihelion distance had been shortened. At time of discovery the object was about 5 months prior tp perihelion.



1975 Mar. 4.77955 = 1975-Mar-04 18:42:33

t - T = -154.454151389 days or about 5 months

r = 3.607 au

delta = 2.704 au

Elongation = 151.5 deg

Orbital Elements at Epoch 2442640.5 (1975-Aug-16.0) TDB

Reference: SAO/1975 (heliocentric ecliptic J2000)



q3.567154 au



node77.7511 deg

peri90.2336 deg

i6.6423 deg


1 fave
Uploaded on April 20, 2018