TESS perigee

From: Bill Gray via Seesat-l <seesat-l_at_satobs.org>
Date: Wed, 2 May 2018 21:43:17 -0400
Hello all,

    A reminder that TESS will reach perigee at about 8:05 UT on 4 May.
The perigee altitude will be about 800 km.  We get one more close
perigee,  on the 13th (I'll write about that when we're closer to it).
After that,  TESS goes past the moon and will be a high-altitude object.
So if you're going to get it while it's bright,  you should seize your
chance.

    I've produced TLEs for this object.  They should be useful when it's
at high altitudes,  but near perigee,  the SGP4/SDP4 model fails by a
few hundred kilometers.  So we're out of luck on that score.  Fortunately,
you can get customized ephemerides at

https://ssd.jpl.nasa.gov/horizons.cgi

    Enter the object name as TESS.

    It looks as if this object should be visible from the southwestern
US,  Hawaii,  and much of South America.  It enters the earth's shadow
at about 07:45 UT,  at an altitude of about 4500 km,  and emerges at
about 8:09,  at about 1000 km.  North America mostly gets to see it
before it enters the shadow.  If you're in,  say,  Brazil,  you ought
to get a good view of it as it emerges.

    I don't really have much of a sense as to how bright it'll be.  I
could imagine it reaching naked-eye visibility shortly after it emerges
from the earth's shadow (seems reasonable for an object with a few
square meters of area for us to look at,  near opposition,  about a
thousand km away),  but I don't really know.

    TESS will be coming in toward us from an elongation of about
60 degrees from the sun,  and then promptly returning to even worse
elongations after it swings past us.  You pretty much get it near
perigee or you don't get it.  (Until it goes past the moon and goes
into its "mission" orbit.  It'll probably get picked up frequently by
the asteroid surveys then.)

    If you do post images,  I'd appreciate links.  I know a few folks
working on TESS who would be interested as well (I find that usually,
the people operating a spacecraft like to see images/videos of their
handiwork out in its "proper" environment).

-- Bill
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Received on Wed May 02 2018 - 20:44:21 UTC

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