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Dátum: 2003-09-06 15:20:45
Feladó: Szabó Sándor
Tárgy: Fw: [PLANOCCULT] Coming Ninina event: target star tested in dawn
Az alábbiakban a szerzo azt ecseteli, hogy kipróbálta a 11-i
hajnali fedés célcsillagát a reggel közeledtével.
Binokulárral egy állványon egészen addig követni tudta, amely
Budapesti szürkületnek felel meg, de egy kis távcsovel még
akár a keleti széleken észlelok is láthatják a fedést.

Szóval csütörtök hajnalban munka elotti pozitív
csillagfedést kívánok!
Térkép a http://okkultaciok.mcse.hu oldalon.

Szabó Sándor

ps. Ja, egy elorejelzés szerint amit csatolt hozzá (de ezen a
listán nem látható), Magyarországon borult lesz, még szerencse
hogy 48 órára már csak 60%-osan tudnak elorejelezni, 72 órára
meg 50%, azaz vagy borult, vagy derült.

----- Original Message -----
From: "jlx"
Cc: ;
Sent: Friday, September 05, 2003 12:42 PM
Subject: [PLANOCCULT] Coming Ninina event: target star tested in dawn

>From J.Lecacheux (France)

On the night of September, Wednesday 10-Thursday 11,
at 3:45-46 UT, 357 NININA, a 106-km asteroid, will
occult the bright V= 6.8 star Hipparcos 29752 =
SAO 95460, in Orion.

According to available S.Preston´s update,
the shadow center should cross France along the axis
Vannes > Orleans > Auxerre > Mulhouse (Mulhausen), then
should continue across s.Germany, Austria and Hungary
along the line Freiburg-im-Breisgau > Konstanz (am
Bodensee) > Salzburg > Budapest... The northern limit
should approach Paris by ~50 km. The big cities of
Munich (München) and Budapest should lie in the
128 km-wide path.

Though the target star is very bright, the most
eastern observers might suffer difficulties from the
dawn, as the asteroidal path will encounter the
astronomical twilight in France at 0 deg. longitude,
the nautical twilight in Germany at +9 deg. longitude
(south of Stuttgart), and the civil twilight in
Hungary at +18 deg. longitude, west of Budapest.

So I observed the target star in dawn this morning,
using 80 mm binoculars (x12) mounted on photographic
tripod, with the intention to simulate occultation
monitoring, and to evaluate real twilight nuisance
for the coming NININA event.

In the following Table, h is the Sun altitude relative
to my apparent horizon (in degrees, negative values).

Q is an estimator of observation easiness, assuming
that the coming Ninina occultation would arise at the
same solar h :
   Q= 1 :  Very easy monitoring, nice conditions.
   Q= 2 :  Still easy to monitor.
   Q= 3 :  Fairly easy yet.
   Q= 4 :  Becoming difficult, due to increasing
           luminous background, but the star is visible
           continuously yet.
   Q= 5 :  Becoming problematic; star lost at moments.
   Q= 6 :  Impossible.

My result :

          h interval         Q

            <-8.1            1
         [-8.1, -6.7]        2
         [-6.7, -5.2]        3
         [-5.2, -3.7]        4
         [-3.7, -3.4]        5
            >-3.3            6

In consequence the Ninina occultation should be easy
in any location along the path in France, s.Germany,
and n.e.Austria, should reach Q=4 (critical level)
only past Budapest in Hungary, should reach Q=5 or
Q=6 (becoming quite impossible) only in Romania near
day terminator.

With stronger magnification (x20 binoculars), or using
telescopes on equatorial mounting, I guess that good
visual observations of the Ninina event could be
obtained even from east of Hungary, with Sun at h ~
-3 degrees.
Moreover it is well known that many CCD-based video
cameras are more insensitive to twilight backgound
than human eye, especially when a red filter is added.
Owing to the 74 deg. solar elongation of the field, a
polarizing filter also can be used to lower a little
the background illumination relative to the star.


My conclusion is that a large amount of people in
central Europe could monitor this nice occultation
on Next Sep. 11 morning, before going to work,
provided that clear sky is present.

Here attached (t05011a.gif), the current GFS meteo
forecast (cloud map for Sep.11, 6h UT) after the
nice website www.wetterzentrale.de  by G.Müller.
Possible clear sky or limited cloud presence from
w.France to Austria.


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