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IAUC 7104: SPACE-MIRROR EXPERIMENT; RX J0812.4-3114; P/1998 U3

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                                                  Circular No. 7104
Central Bureau for Astronomical Telegrams
Mailstop 18, Smithsonian Astrophysical Observatory, Cambridge, MA 02138, U.S.A.
IAUSUBS@CFA.HARVARD.EDU or FAX 617-495-7231 (subscriptions)
URL http://cfa-www.harvard.edu/iau/cbat.html  ISSN 0081-0304
Phone 617-495-7244/7440/7444 (for emergency use only)

     On Feb. 4, the Russian Znamya-2.5 space-mirror experiment,
attached to the Progress M-40 spacecraft in low-earth orbit, will
be used to illuminate selected nighttime regions of the earth with
reflected sunlight at an intensity of up to 10 times that of the
full moon.  The illumination patch is predicted to be 6 km in
diameter and will pass over a given site in about 1 to 2 seconds.
Observatories may wish to take precautions to avoid damage to
equipment and observations.  The experiment is scheduled to last
from Feb. 4.482 to 5.092 UT, and announced targets include
Kazakstan, Ukraine, Belgium, Germany, Canada, and the northern
U.S.A.  More details of the experiment program are available at
http://src.space.ru/page_30e.htm and
http://www.skypub.com/news/special/znamya.html.  A resolution
adopted by the IAU General Assembly in Kyoto in 1997 notes that the
launch of large, luminous objects in orbit around the earth is
likely to "have deleterious effects on astronomical observations,
[and as] the night sky is the heritage of all humanity, which
should therefore be preserved untouched, . . . the appropriate
authorities [should] ensure that the night sky receives no less
protection than has been given to the world heritage sites on

RX J0812.4-3114
     R. Corbet, Goddard Space Flight Center (GSFC) and Universities
Space Research Association, reports on behalf of the RXTE ASM team
at GSFC and the Massachusetts Institute of Technology: "An analysis
of the RXTE All Sky Monitor light curve of the transient x-ray
source RX J0812.4-3114 (= LS 992, Motch et al. 1999, A.Ap. 323,
853) obtained between 1996 Jan. 5 and 1999 Jan. 28 reveals a
modulation at a period of about 81 days.  The source appears to
have been in a lower flux state until early in 1998, when the
81-day outbursts became visible at levels of about 1 ASM count/s
(10 mCrab).  If these outbursts continue, then the next predicted
maximum is at about 1999 Mar. 25, and observations are encouraged
at that time to search for pulsations from this likely Be/neutron
star binary."

     Total visual magnitude estimates:  Jan. 5.75 UT, 10.8 (W.
Hasubick, Buchloe, Germany, 0.44-m reflector); 11.02, 10.5 (J.
Bortle, Stormville, NY, 0.41-m reflector); 18.91, 10.2 (K. Hornoch,
Lelekovice, Czech Republic, 0.35-m reflector); 27.57, 10.9 (N.
Biver, Oahu, HI, 0.26-m reflector).

                      (C) Copyright 1999 CBAT
1999 February 3                (7104)            Daniel W. E. Green

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