Aπόκρυψη από TNO στις 18 Οκτ (μικρές πιθανότητες)

[vtsamis]

The binary trans-Neptunian asteroid (160256) 2002 PD149 could occult a V= 12.8, R= 12.5 star in Aquarius on next Monday Oct.18 evening, around 19:00 UT.

 

The projected track of the centre of masses was predicted by Euraster 8 000 km north-east (+/-14 000 km) from our European countries :

 

http://www.euraster.net/pred/20101018%20160256%202002%20PD149%2012.6.gif

 

I have found a quite similar track by replacing the UCAC2 catalog by the UCAC3 (cf. the here attached map pd14918xU3.gif), or by the PPMx.

The lateral uncertainty is 14 000 km according to "Occult", or 23 000 km if we rely upon "AstDys" data instead.

 

Prediction maps like pd14918xU3.gif are very misleading, as actually no matter exists near the centre of masses of a binary system. Inevitably the two shadows will pass elsewhere, one northside and the other southside, probably at large distance. So the southernmost shadow of 2002 PD149 may interess us.

 

In this double TNO the main body "A" is about 220 km large (?) and revolves at the very approximate distance 11 000 km from the centre of masses. The satellite "B" is about 180 km large (?) and revolves, opposite to "A", at nearly 13 000 km from the centre of masses.

We only know that the A-B projected distance was 24 400 km at the binarity discovery time, in May 2007. The mean A-B distance (i.e. orbital radius) and the common revolution period are still unknown.

 

We may conclude from these excessively uncertain data that either A, or B, or even both A and B, but possibly none from them (!)..., will produce a 8 - 10 seconds occultation within

the one hour interval 18:30-19:30 on next Monday.

 

The probability P of positive occultation is very faint in any location, but, as 220+180= 400, will be nearly the same for the A + B couple as for a virtual 400 km single body.

My best estimate for a single station in Europe is P ~ 0.6 %, or P ~ 0.5 % (i.e. barely lower) 10 000 km farther from the nominal centre, in west Australia.

 

Good luck to whoever will attempt !

 

J.Lecacheux

[Bi2L]

Βαγγέλη σε ευχαριστούμε για την Πληροφορία, θα δούμε τι θα κάνουμε (ελπιζω να μην παω λαθος μερα παλι...)

Εαν η προηγούμενη απόκρυψη είχε 1% ....αυτη εδω πόσο % έχει;;

[vtsamis]

...in Europe is P ~ 0.6 %

Αλλά το πρόβλημα είναι η κακοκαιρία και τα έκτακτα καιρικά φαινόμενα που αναγγέλθηκαν πριν λίγο.

Το 0.6% παλεύεται, η κακοκαιρία δεν παλεύεται