Central Bureau for Astronomical Telegrams
IAUC 6701: C/1996 H1; eta Car; 1997cx
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Circular No. 6701
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/cfa/ps/cbat.html
Phone 617-495-7244/7440/7444 (for emergency use only)
COMET C/1996 H1 (SOHO)
C. St. Cyr, Naval Research Laboratory, reports, for the SOHO-LASCO
Consortium (see IAUC 6685), the discovery by B. McCarty and D. Biesecker
of another Kreutz sungrazer in SOHO-LASCO C3 coronagraph archival data.
Measurements by Biesecker have been reduced by G. V. Williams and are
given on MPEC 1997-O05 in detail, the approximate discovery position being:
1996 UT R.A. (2000) Decl.
Apr. 29.155 2 43.6 +11 52
The comet was estimated to vary between mag 5 and 9, and there may have
been a tail in the single C2 image (on Apr. 30.202 UT). The orbit computed
by the undersigned, also given in detail on MPEC 1997-O05, indicates
perhelion passage on Apr. 30.50.
eta CARINAE
M. F. Corcoran, Goddard Space Flight Center (GSFC) and
Universities Space Research Association; J. H. Swank and R. Petre, GSFC;
and K. Ishibashi and K. Davidson, University of
Minnesota, report: "Target of Opportunity observations with the Rossi
X-ray Timing Explorer (RXTE) of the peculiar luminous star eta Car
starting June 20 show significant x-ray variability on timescales of
days and confirm the presence of an x-ray peak on July 4.96 UT.
This is close to the time of the predicted peak based on the 85.1-day
period previously reported (IAUC 6668), and it strongly suggests that
at least some of the 2-10-keV flux variability is periodic.
Using a conversion factor of 3.22 x 10**-12 erg s-1 cm-2 per PCA count,
the background-corrected flux in the 2-10-keV band was
1.29 x 10**-10 erg s-1 cm-2 on July 4.96. This was 7.5 percent larger than
the previous peak on Apr. 10. The 2-10-keV
flux declined to 1.05 x 10**-10 erg s-1 cm-2 on July 11.
Continued monitoring at x-ray and other energies is needed to
identify the cause of the periodic emission. Dates of
upcoming and previous RXTE observations of eta Car, as well as
recent RXTE lightcurves, are available from
http://lheawww.gsfc.nasa.gov/users/corcoran/eta_car/eta_car_xte.html"
SUPERNOVA 1997cx IN NGC 3057
S. Jha, Harvard-Smithsonian Center for Astrophysics, notes that
the Whipple Observatory images of SN 1997cx (cf. IAUC 6700)
show it to be 5" west and 15" north (not south) of the center of NGC 3057.
(C) Copyright 1997 CBAT
1997 July 17 (6701) Brian G. Marsden
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