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Update 21 June 2010

The Pluto stellar occultation
of 4 July 2010

On 4 July 2010 around 02:00 UT (night of July 3rd to 4th, 2010), Pluto's occults a star with Rmag~ 15.3, Kmag~ 9.8, as seen from southern Africa and South America.

Photometry of the star (Vizier site) available here (pdf sheet).

Astrometric J2000 position (Assafin et al, Rio de Janeiro group):

α= 18h 15mn 42.1015 sec
δ= -18d 16' 41.096"
(Updated May 2010, 2 nights at 0.6m-telescope Pico dos Dias, Brazil)

The corresponding star apparent airless position of the day is:

α= 18h 16mn 21.6 sec
δ= -18d 16' 27"

Pluto's offset with respect to the JPL DE413/PLU017 ephemeris is taken to be:

Δα cos(Δ)= -10.5 mas and
Δδ=+153.4 mas

This offset is derived from a linear fit to offsets observed between July 2005 and February 2010, during positive detections of stellar occultations by Charon and Pluto.

Using the star position and Pluto's ephemeris offset given above, we get the following map:

Click on images for enhancement

- the shadow moves from right to left
- the larger dot is geocentric closest approach (corresponding to the time "h:m:s UT" given below the map)
- small dots are plotted every minute
- solid lines correspond to occultation half-light level (radius 1225 km)
- dotted lines correspond to occultation detection limit (radius 1560 km), with a stellar drop of less than 1%
- uncertainty is about +/- 800 km in NS direction, and +/- 1mn in time
- red star symbols are potential observing sites

11.1x10.7 and 2.8 x 2.7 arcmin charts. Note the dark cloud obscuring the field of view at right.

Click on images for enhancement

Note that independent predictions are being published on the MIT page.
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