Sziasztok!
Csak annyit, aki keveset tud angolul, min én...annak ajánlom:
http://www.webforditas.hu/
hasznos!!!!!
G.Ati-NAE
-----Original Message-----
From: listserv@mcse.hu [mailto:listserv@mcse.hu]On Behalf Of POTLEO-l:
Tepliczky István
Sent: Wednesday, December 13, 2006 1:01 PM
To: agazdag@gylcomp.hu
Subject: [Fwd: CBET 773: 20061212 : GEMINID AND URSID METEORS 2006]
A korrekt információtovábbítás kedvéért fw-olom Central Bureau for
Astronomical Telegrams hivatalos körlevelét (CBET) Geminida-maximum
ügyben. Elnézést, akiket kevésbé érdekel ill. kevésbé értenek angolul.
Üdv:
Tepi
-------- Original Message --------
Subject: CBET 773: 20061212 : GEMINID AND URSID METEORS 2006
Date: 12 Dec 2006 09:55:38 -0000
From: Lucia
To: tepi@mcse.hu
Electronic Telegram
No. 773
Central Bureau for Astronomical Telegrams
INTERNATIONAL ASTRONOMICAL UNION
M.S. 18, Smithsonian Astrophysical Observatory, Cambridge, MA 02138, U.S.A.
IAUSUBS@CFA.HARVARD.EDU or FAX 617-495-7231 (subscriptions)
CBAT@CFA.HARVARD.EDU (science)
URL http://cfa-www.harvard.edu/iau/cbat.html
GEMINID AND URSID METEORS 2006
P. Jenniskens, SETI Institute, reports that the Geminid meteors from
(3200) Phaethon should peak at ZHR = 130 +/- 20 meteors/hr on 2006 Dec.
14d08h48m UT, with a FWHM of 26 hr (Jenniskens 2006, Meteor Showers and
Their Parent Comets, Cambridge Univ. Press, p. 397). A waning 31-percent
crecent moon will not interfere before 1 a.m. local time. Meteors should
radiate from a geocentric radiant of R.A. = 113.8 deg, Decl. = +32.4 deg
(equinox 2000.0), with velocities of V_g = 34.6 km/s. On average, Geminids
are fainter in the days leading up to the peak than they are following the
peak; at its peak, the magnitude-distribution index (cf. CBET 710) is
predicted to be chi = 2.7.
Jenniskens adds that E. Lyytinen and M. Nissinen (Helsinki, Finland)
have identified an encounter of the earth with the 75-revolution dust trail
(dating back to 996 AD) of comet 8P/Tuttle around 2006 Dec. 22d19h27m UT,
with meteoroids in the earth´s path between 18h10m and 20h50m, depending on
the adopted value for nongravitational acceleration (this updates Jenniskens
2006, Meteor Showers and their Parent Comets, Cambridge Univ. Press, p.
641).
A 6-percent moon in Cap will not interfere. Meteors should radiate from a
geocentric radiant of R.A. = 217.56 deg, Decl. = +74.93 deg (equinox
2000.0),
with velocities of V_g = 33.83 km/s. Particles could be mostly faint with a
magnitude-distrubtion index of chi around 2.8. A predicted peak rate of ZHR
around 35 meteors/hr would be about three times that of the annual Ursids.
The calculations assume that, back in 996 AD, 8P/Tuttle behaved much as it
does now. The previous oldest trail traced into the earth´s path (in AD
2000) is dated to AD 1405. The meteoroid orbits are not strongly perturbed
by Jupiter, so that the meteoroids tend to accumulate over time in a
component called a "filament" (such filaments are known from comets 109P,
55P, 1P, and 8P). Jenniskens also points out that it is possible that a
broader (FWHM = 8.5 hr) filament dust component will return, peaking at
around 2006 Dec. 22d17h38m with ZHR around 39 meteors/hr and with chi = 2.6.
That filament was seen before 1982 and in 1993-1998, during previous returns
of the comet to perihelion. The 1945 display was identified by Jenniskens
et al. (2002, Icarus 159, 197-209) as due to a more-or-less well-behaved
dust trailet ejected in 1392; the calculated peak time of the shower was
1945 Dec. 22d18h29m UT, close to the time of the observations. Comet
8P/Tuttle is due back at perihelion on 2008 Jan. 26.9 TT (MPC 54167).
NOTE: These ´Central Bureau Electronic Telegrams´ are sometimes
superseded by text appearing later in the printed IAU Circulars.
(C) Copyright 2006 CBAT
2006 December 12 (CBET 773) Daniel W. E. Green