[Neocp_artsats] C3RP361 = Multijunk

[Bill Gray]

Hi folks,

    ...As are six other previous NEOCP tracklets,  including one that 
actually got designated as a NEO.

    'Multijunk' has basically been lost since April.  With the benefit 
of the C3RP361 arc,  it turns out that this object was on NEOCP as :

C9G6TY2, Sep 07, suspected artificial
A10WBFl, Sep 06, not confirmed
ZTs0148, Aug 27, designated 2023 QB20
ZTs0147, Aug 23, not confirmed
ZTs0139, Aug 06, not confirmed
ZTs0138, Jul 27, not confirmed

    I've updated TLEs accordingly.

    Except for C9G6TY2,  none of the arcs was long enough to look 
suspiciously artificial.  That last looked kinda Multijunk-y,  but the 
motion looked wrong (it _is_ an ETBO,  and getting a good motion match 
is difficult).

    ZTs0148 = 2023 QB20 is the problematic case.  Shortly after ZTF got 
it,  two stations provided reasonable-looking but (I'm about 95% sure) 
spurious follow-up tracklets and it got designated on MPEC 2023-R140.  I 
suspect both follow-ups used the tried-and-true procedure of looking at 
the MPC ephems,  imaging the indicated areas,  and measuring a hot 
pixel.  Nobody else "found" it,  and it was bright enough that you'd 
think somebody would have.

    The only reason for the 5% doubt is that _two_ stations found it. 
The uncertainty for the first was large enough to let them image it, 
select a suitable hot pixel,  and say "that's it".  The second follow-up 
was somewhat more constrained and would have made that sort of thing 
more difficult to do,  and the resulting three tracklets make a 
plausible NEO orbit.  None of the observations line up with Gaia stars.

    If 2023 QB20 is "real",  it should appear in several ATLAS images. 
I've sent a list of those images to the ATLAS folks for whom I have 
e-mail addresses,  and hope to persuade them to look for it.  If they 
don't find it (as I expect will be the case),  that 95% can be bumped up 
to 100%,  and I'll put in a Jira ticket with MPC.

-- Bill