[neo_followup] 2020 SO observations?

[Bill Gray]

Hi folks,

    This is actually junk,  the Centaur stage from the Surveyor
2 mission in 1966.

    Apparently,  radar observations are planned for this object.
You'd think (well,  _I_ at least thought) that the current
astrometry would define the orbit nicely.  However,  we're at
the point where you can't fit the orbit well without including
additional non-gravitational forces,  and it's close in (meaning
faster apparent motion and more along-track ephemeris error),
_and_ it's somewhat close to the moon (about nine degrees right
now),  so we aren't getting routine survey data.  As a result,
the ephemeris uncertainty is already several arcseconds.

    All of which is a long-winded way of saying that it'd be a
good idea to get some astrometry on this object,  and/or a
light curve or rotation period (it's getting quite bright...
at mag 17.2 as I write this,  but that's because it's
emerging from the earth's shadow;  it'll be back up to 15.4
in an hour or so.)

    The rotation period is a useful bit of info for radar
observation planning.  The faster it rotates,  the more the
returned signal is "spread out" in frequency,  and it can
help to know that ahead of time.

    Usual comments about the need to be _really_ careful about
timing;  a one-second timing error now would correspond to
roughly a two-arcsecond measurement error,  i.e.,  huge.
We could still use your data,  but only partly ("the object
passed this point",  instead of "the object passed this point
at this time".)

-- Bill