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IAUC 7320: LUNAR LEONID METEORS; DD Cir

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                                                  Circular No. 7320
Central Bureau for Astronomical Telegrams
INTERNATIONAL ASTRONOMICAL UNION
Mailstop 18, Smithsonian Astrophysical Observatory, Cambridge, MA 02138, U.S.A.
IAUSUBS@CFA.HARVARD.EDU or FAX 617-495-7231 (subscriptions)
BMARSDEN@CFA.HARVARD.EDU or DGREEN@CFA.HARVARD.EDU (science)
URL http://cfa-www.harvard.edu/iau/cbat.html  ISSN 0081-0304
Phone 617-495-7244/7440/7444 (for emergency use only)


LUNAR LEONID METEORS
     On Nov. 19 D. W. Dunham, Applied Physics Laboratory, Johns Hopkins
University, reported the visual observation by B. Cudnik (Houston, TX, 0.36-m
telescope) on Nov. 18 of a brief flash near the center of the moon's dark
limb, at least as bright as psi1 Aqr nearby.  This event, 1'.7 from the moon's
edge, was apparently confirmed by Dunham (Mount Airy, MD, 0.13-m telescope) on
two half-frames of a videotape that showed fading by about 5 mag during the
intervening 1/60 second.  On Nov. 23 and 24 Dunham reported his confirmation
of two lunar flashes videorecorded by P. V. Sada (Monterrey, Mexico, 0.13-m
telescope) half an hour after Cudnik's observation, as well as of two lunar
flashes videorecorded by D. Palmer (Greenbelt, MD) up to an hour or so earlier;
there was also a probable untimed additional visual confirmation of the Cudnik
event by S. Hendrix (Cameron, MO, 0.11-m telescope).  Dunham has summarized
his own measurements of the five Nov. 18 events as follows:

Disc.            UT            m1  m2  lambda beta    Lunar location
         h  m   s        s             deg    deg
Palmer   3 49 40.5  +/- 0.4    3   7   48 W    1 N   175 km SW of Kepler
Palmer   4 08 04.1  +/- 0.6    5   8   70 W   15 S   175 km S of Grimaldi
Cudnik   4 46 15.2  +/- 0.1    3   8   71 W   14 N    50 km ENE of Cardanus
Sada     5 14 12.93 +/- 0.05   7   8   58 W   15 N   200 km WNW of Marius
Sada     5 15 20.23 +/- 0.05   4   7   59 W   21 N    75 km S of Schiaparelli

The magnitude m1 is that on the first frame showing the event, m2 that on the
following half-frame; the first event listed also seems to be present on a
third half-frame at mag 9.  The selenographic coordinates (longitude lambda
and latitude beta) and lunar location for the first two events are uncertain
by 5 deg or more, but the others should be accurate to within about 2 deg
(50 km).  Following Dunham's suggestion that the flashes resulted from Leonid
impacts on the moon, D. J. Asher, Armagh Observatory, computed that the
center of the 1899 dust trail that evidently produced the 1999 Nov. 18 Leonid
activity (cf. IAUC 7311) by nominally passing 0.0007 AU from the geocenter
would have passed 0.0002 AU from the selenocenter around 4h49m UT.


DD CIRCINI
     A. C. Gilmore provides further photometry of DD Cir = Nova Cir 1999,
obtained as before (see IAUC 7249): Sept. 3.415 UT, V = 10.42, U-B = -0.43,
B-V = +0.38, V-R = +2.01, V-I = +1.65, airmass = 1.50; 4.389, 10.38, -0.43,
+0.35, +2.00, +1.57, 1.42; 13.368, 10.98, -0.46, +0.14, +1.82, +1.05, 1.43.
Standard deviations are 0.01 mag or less.

                      (C) Copyright 1999 CBAT
1999 November 26               (7320)              Brian G. Marsden

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