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The Pluto stellar occultation of 31 July 2007
(visible from New Zealand and Southern Australia).
Update: 30 July 2007



What will happen?

On 31 July 2007 near ~ 13:45 UT, Pluto may occult a star, as seen from New Zealand and Southern Australia.

Coordinates of star, from Rio de Janeiro group:
r.a.= 17h 45mn 41.9894 sec
dec.= -16d 29' 31.639" (ICRF J2000)

Coordinates of star, from Geneva (Raoul Behrend):
r.a.= 17h 45mn 41.9854 sec
dec.= -16d 29' 31.613" (ICRF J2000)

The corresponding shadow maps are shown below:

Click on images for enhancement
Rio de Janeiro prediction
Geneva prediction
click click
NB. Black lines: Pluto half-light shadow, dotted lines: Pluto 1% drop shadow (barely detectable)
dots plotted every mn, shadows move from right to left.

An offset of Pluto's system of -100 mas in right ascension (toward celestial west) and +80 mas (toward celestial north) has been applied to Pluto's DE413 ephemeris. This offset has been observed during the stellar occultation of 18 March 2007, and again during the 12 May 2007 and 14 June 2007 events.
!!! ** IF THIS OFFSET IS MAINTAINED ON 31 JULY 2007, THEN WE OBTAIN THE MAPS ABOVE.. ** !!!
However, this offset is not currently understood, so that it may be hazardous to apply at face value for the 31 July 2007 event!!!

Star magnitudes, see Vizier service:

Star magnitudes: B= 13.9 V= 13.2 R= 13.7 I= 12.5 J= 11.6 H= 11.3 K= 11.1
Pluto/Charon: B= 15.2 V= 14.4 I= 13.6 J= 13.0 H=12.9 K= 13.0

Thus, the star is about 1 magn **brighter** than Pluto in all visual bands, a rather unusal situation (occuted star in the galactic center tend to be quite red, i.e. collapse in the blue), and almost 2 magn **brighter** than Pluto in near IR.

Chart from Aladin DSS2 660 nm
North is up, East is left. Field of view is 8.9x8.9 arcmin. The target is at center of FOV (red arrow).
click

For contacts, more information and/or comments, you can contact me me email at:

bruno.sicardy@obspm.fr

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