[Neocp_artsats] ZTF0KSa = artsat, possibly = ZTF0K7X

Bill Gray pluto at projectpluto.com
Tue Feb 9 08:35:12 EST 2021


    If I try to fit a barely hyperbolic (from the geocentric
viewpoint) orbit to this,  the cross-track residuals for the
last two observations go from ~0.4 arcsec to over 1.1 arcsec,
and the overall fit is quite poor.

    I think this is a repeat of ZTF0K7X,  an object observed
over 70 seconds a month ago (elements below).  In neither case
do we have a particularly good orbit,  and this could be
coincidence (less likely) or two bits launched into a similar
orbit that haven't drifted apart all that much (more likely).

    Putting the fact that a non-junk orbit results in really
bad residuals,  plus the similarity to an earlier object,
is enough to diagnose it as junk in my mind.

-- Bill

Orbital elements:  ZTF0KSa
    Perigee 2021 Feb 8.64677932 +/- 0.372 TT = 15:31:21.733 (JD 2459254.14677932)
Epoch 2021 Feb  9.0 TT = JDT 2459254.5                        Gray
M  93.72873500240 +/- 60            (J2000 equator)
n 265.35460892881 +/- 125           Peri.  352.22851106 +/- 22
a 51766.9306887 +/- 16277           Node   330.79644633 +/- 0.6
e   0.3137838238 +/- 0.249          Incl.   36.09541733 +/- 0.9
P1953.58m/1.357d           H 32.7   G  0.15   U 16.0
q 35523.3052266 +/- 24035    Q 68010.5561507 +/- 8519
 From 4 observations 2021 Feb. 9 (3.0 hr); mean residual 0".497

Orbital elements:  ZTF0K7X
    Perigee 2021 Jan 13.10186186 +/- 37.4 TT =  2:26:40.864 (JD 2459227.60186186)
Epoch 2021 Jan 14.0 TT = JDT 2459228.5                        Gray
M 156.34045455543 +/- 29            (J2000 equator)
n 174.07172376928 +/- 0.274         Peri.  335.51641787 +/- 60
a 68567.4533177 +/- 3.29e+7         Node   320.06006902 +/- 70
e   0.7016322563 +/- 0.161          Incl.   40.80376090 +/- 2.9
P2978.03m/2.068d           H 32.1   G  0.15   U 11.9  SR
q 20458.3163348 +/- 2.41e+7    Q 116676.590300 +/- 1.48e+8
 From 4 observations 2021 Jan. 14 (70.1 sec); mean residual 1".363



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