A megfigyelést ma éjjal :- között, azaz 40 percig kellene végezni a bizonytalan pálya és a TNO lassú mozgása
miatt.

Szabó S.

----- Original Message -----
From: "rdapt"
To: "planoccult"
Cc: "jlx" ; "jlx" ; "jlx" ; "jlx"
Sent: Friday, October 25, 2002 9:34 AM
Subject: [PLANOCCULT] Trans Neptunian


> >From J.Lecacheux
>
> Thierry Pauwels wrote :
>
> > > From J.Lecacheux
> > >
> > > On Oct. 25-26 around 1:26 UT (i.e. next Saturday morning) the large
> > > TNO #15874 (still unnamed), alias 1996TL66, will pass very close to
> > > the magn. 8.7 star HIP 13530, alias SAO 93172.
> > > Owing to large ephemeris uncertainties, occultation could occur from
> > > any place in Africa, Europe, s.America and a large part of n.America.
> > >
> > > Note that time uncertainty is several minutes, so the target star
> > > should be monitored from 1:15 to 1:35 UT.
> >
> > Are you sure this is enough ? The uncertainty in position is nominally
> > about 0.5" (E. Bowell), but this is often underestimated.  And to have 95%
> > of success in case there is an occultation, one should observe the time to
> > travel four times this uncertainty.  With the very slow apparent speed of
> > (15874), I get an interval of at least 40 minutes, but given the
> > usual underestimation of the uncertainty in position, I think that
> > observing for a full hour would be safer.
> >
> > Thierry Pauwels
> >
> > With kind regards,  ---   Beste groeten,
>
>
>     Thierry, you are right. The 20 mn interval that I recommended in my message is not enough. Assuming that
the claimed 0".5
> uncertainty has equal projections along the motion vector and perpendicular to it, we have to consider a
time interval   1/v* (4 *
> 0".5 /sqr(2)), where v= 3".488/h will be the hourly motion of this TNO : so I obtain 24 minutes. But
according to your remark that
> the 0".5 uncertainty might be underestimated, monitoring the target from 1:05 to 1:45 UT will be far better.
>     The lateral component 2* 0".5 /sqr(2) of the uncertainty will correspond to 1.4 terrestrial diameter.
Europe is
> far from the center of the probability box. Prospects in South-Africa are better.
>
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