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IAUC 6958: 1998cu; XTE J2123-058; C/1998 H1

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                                                 Circular No. 6958
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
Phone 617-495-7244/7440/7444 (for emergency use only)


SUPERNOVA 1998cu IN IC 1525
     W. D. Li, M. Modjaz, R. R. Treffers, and A. V. Filippenko,
University of California at Berkeley, report their discovery of an
apparent supernova during the course of the Lick Observatory
Supernova Search (cf. IAUC 6627) with the 0.8-m Katzman Automatic
Imaging Telescope (KAIT), as part of a cooperative program with the
Beijing Astronomical Observatory (BAO) Supernova Survey (cf. IAUC
6379).  SN 1998cu was found and confirmed in unfiltered CCD images
obtained on June 29.4 (mag about 18.4) and 30.4 UT (mag about
18.1).  The new object is located at R.A. = 23h59m12s.95, Decl. =
+46o52'31".8 (equinox 2000.0), which is about 29".2 west and 50".3
south of the nucleus of IC 1525.  BAO images (limiting mag about
18.5) obtained on May 29 and June 17 do not show a star at the
position of the supernova; a KAIT image of IC 1525 taken on 1997
Dec. 26 (limiting mag about 19.0) also shows nothing at this position.


XTE J2123-058
     T. Takeshima, Goddard Space Flight Center (GSFC) and
Universities Space Research Association; and T. E. Strohmayer,
GSFC, on behalf of the RXTE Science Operations Center, write:  "We
report an improved position for this transient (IAUC 6955) of R.A.
= 21h23m16s, Decl. = -5 47'.5 (equinox 2000.0), with an uncertainty
of 1', based on scans across the source with the Proportional
Counter Array on RXTE on June 29.04 UT.  This is consistent with
the position of the candidate of an optical counterpart reported on
IAUC 6957.  Two weak bursts were seen during the pointed
observations on June 27.98 and 29.70.  Preliminary spectral
analysis suggests that they are type-I (thermonuclear) bursts; thus
the system is likely a low-mass x-ray binary with a neutron star.
The He II emission reported by Tomsick et al. (IAUC 6957) also
supports this hypothesis.  The observed steady fluxes (2-10 keV) on
June 27.09, 29.04, and 29.70 were 65, 67, and 56 mCrab,
respectively.  The observed burst peak fluxes above the steady flux
level (2-10 keV) were 50 and 88 mCrab."


COMET C/1998 H1 (STONEHOUSE)
     Visual m_1 estimates (L = reflector):  May 14.92 UT, 11.1 (G.
Comello, Roden, The Netherlands, 0.30-m L); 23.12, 11.5 (J. Bortle,
Stormville, NY, 0.41-m L); June 2.89, 12.5 (M. Lehky, Hradec
Kralove, Czech Republic, 0.42-m L); 29.89, 13.8 (K. Hornoch,
Lelekovice, Czech Republic, 0.35-m L).

                      (C) Copyright 1998 CBAT
1998 June 30                   (6958)            Daniel W. E. Green

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