Central Bureau for Astronomical Telegrams
IAUC 7522: LEONID METEORS 2000; Her X-1; C/1999 T1
The following International Astronomical Union Circular may be linked-to from your own Web pages, but must not otherwise be redistributed (see these notes on the conditions under which circulars are made available on our WWW site).
Read IAUC 7523
.dvi or
.ps format.
Circular No. 7522
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)
CBAT@CFA.HARVARD.EDU (science)
URL http://cfa-www.harvard.edu/iau/cbat.html ISSN 0081-0304
Phone 617-495-7440/7244/7444 (for emergency use only)
LEONID METEORS 2000
M. Gyssens, International Meteor Organization, reports that
there may have been several peaks in terms of the intensity of
Leonid meteors on Nov. 17 and 18, as seen in preliminary data
contributed by numerous observers worldwide. There may have been
minor peaks (ZHR about 100) near Nov. 17.25 and 17.33 UT, before
activity began rising noticeably around Nov. 18.0. Two significant
peaks, during Nov. 18.1-18.2 (ZHR about 200-300) and about 18.30
+/- 0.01 (ZHR about 400), appear to confirm the predictions by
McNaught and Asher (1999, WGN 27, 85), which are based on the
theory that the observed peaks represent debris ejected from comet
55P/Tempel-Tuttle eight and four revolutions ago, respectively.
HERCULES X-1
B. Boroson, College of Wooster; S. D. Vrtilek, Smithsonian
Astrophysical Observatory; P. Boyd, NASA Goddard Space Flight
Center; and A. Levine, Center for Space Research, Massachusetts
Institute of Technology, write: ''Data from the All Sky Monitor
(ASM) on the Rossi X-ray Timing Explorer (RXTE) suggest that the
x-ray binary pulsar Hercules X-1 has emerged from the x-ray low
state it entered in Mar. 1999 (IAUC 7139). In the period from Nov.
13.0 to 17.2 UT, four out of five averages of 25 ASM observations
each detect Hercules X-1 with at least 15-sigma significance. The
count rate peaks near 5 counts/s, corresponding to a flux of 60
mCrab. The average of 25 observations that was not 15-sigma-
significant overlapped the expected eclipse of Hercules X-1.
Hercules X-1 was also detected by the ASM over an about 5-day
period with a peak of 6 counts/s (80 mCrab) on Oct. 12 (35 days
prior to the current detection). Hercules X-1 historically has
shown a 35-day x-ray cycle peaking near 6 counts/s in the RXTE ASM.
Pointed x-ray observations to determine the spectrum and spin
evolution are encouraged, as are observations at other wavelengths.
Real-time quick-look data can be obtained at
http://heasarc.gsfc.nasa.gov/cgi-bin/xte_weather/xte_lc?source=HERX1,
and daily averages of quick-look data over the entire mission can
be obtained at http://xte.mit.edu/."
COMET C/1999 T1 (McNAUGHT-HARTLEY)
Total visual magnitude estimates: Oct. 27.75 UT, 8.9 (M.
Mattiazzo, Wallaroo, S. Australia, 25x100 binoculars); Nov. 3.72,
8.6 (D. A. J. Seargent, The Entrance, N.S.W., 25x100 binoculars);
19.63, 8.5 (S. T. Rae, Whakatane, New Zealand, 0.15-m reflector).
(C) Copyright 2000 CBAT
2000 November 20 (7522) Daniel W. E. Green
Read IAUC 7523
.dvi or
.ps format.
Our Web policy. Index to the CBAT/MPC/ICQ pages.
