Asteroid Eros: Close Approach in January

 Fw: Your chance to reenact a key moment in astronomy history!

Sunday, January 1, 2012 7:40 AM

From: "dfischer@ASTRO.UNI-BONN.DE" <dfischer@ASTRO.UNI-BONN.DE>

To: HASTRO-L@listserv.wvu.edu

Early this year there will be an unusually good apparition of asteroid
(433) Eros, coming to within 0.18 AU in the coming weeks and reaching 8th
magnitude. Such close approaches have been used in the last century - esp.
in 1900/1 and 1930, according to
http://www.rasnz.org.nz/MinorP/2012Eros.htm and
http://en.wikipedia.org/wiki/Astronomical_unit#History - to determine the
Astronomical Unit with higher precision than was possible from the
Transits of Venus in the two preceding centuries. So in 2012 we have the
rare opportunity to reenact *both* historical key methods for determining
the AU, first with Eros and a few months later with Venus!

While numerous projects to use the ToV for getting the AU are in
preparation (as they were in 2004), there is now also the proposal for
coordinated photographic observations of Eros in January and February:
sought are image pairs taken at precisely the same moment in different
countries; see
http://transitofvenus.nl/wp/2012/01/01/eros-and-the-solar-parallax for
details. Eros' brightness will peak at 8.6 mag. in late January while the
initially excellent maximum altitude (elevation) slowly shrinks throughout
the month for the N hemisphere. Just to get a 'feeling' for the geometry I
checked pairings between Germany and India (Cologne vs. Delhi):

Jan. 15 23:00 UTC Germany: 32 degrees vs. India: 67 degrees. 8.9 mag. Leo.
Jan. 25 23:00 UTC Germany: 29 degrees vs. India: 53 degrees. 8.6 mag. Sex.
Feb.  5 23:00 UTC Germany: 23 degrees vs. India: 35 degrees. 8.g mag. Sex.

So it *can* be done - all that's needed are pairs of observers in two
countries, precise coordination and good weather. If you are capable of
imaging a 9th magnitude object clearly between the stars or know amateur
astronomers who are, *please* get involved - and activate all
international networks! The image pairs obtained this way alone should
have great didactical value - and perhaps we even learn something new
about the history of astronomy this way ...

Daniel Fischer


gaw

Glenn A. Walsh, Project Director,
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