As viewed from Saturn, Venus will transit the Sun on 2012 December 21, for about 11 hours. The Cassini spacecraft will observe the Sun from Saturnian orbit during the transit. Venus and Saturn however are positioned on the other
side of the Sun from Earth on this date, and only the first ~2.5 hours of the event will occur where the projected location on the Sun of the extension of Saturn-Venus line visible from Earth; we refer to the projection on the solar
surface as the ``footprint'' on the Sun of the Venus-as-seen-from-Saturn track. This proposal is for Hinode SOT observations to support the Cassini study by observing with high resolution this Venusian footprint location on the
Sun.
The potential Hinode observations will be restricted to times if and when this footprint crosses the expected location of plage or active regions. Major Flare Watch observations or other key Hinode observations or activities have a
higher priority than these SToV observations.
The location of the SToV footprint as seen from Hinode has been provided by plan team member G. Schneider, with calculations done by Jon Giorgini of JPL. The SToV footprint will be visible from Hinode on 21 December 2012, 11:10-13:30 UT. On that day, Venus as seen from Earth will be ~11'' in diameter, and hence this is the angular size of the deprojected SToV footprint of Venus. Using this information, and assuming an SOT FOV of about 200'' X 100'', we have determined the needed pointings for the period of time. That information is given in the Remarks section below. Plan team member A. Sterling will attend the relevant Hinode morning meetings to assist with the planning.
The detailed content of these observations is very similar to that of the Jupiter ToV (JToV) observations of 20 September 2012, described in HOP 218. The next planetary transit of this nature will be a transit of Earth as seen from Jupiter (JToE), 5 January 2014. |
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