(cba:news) IAUC 8131: 2003ef; V4743 Sgr (fwd)

Joe Patterson jop at astro.columbia.edu
Tue May 13 09:52:31 EDT 2003

Oh yeah - I was very fascinated to read this yesterday!  I imagine some of
you (Berto?) keep up with young southern novae better than I do.  Can
anyone clarify whether this is a feasible target for a CBA study?  If it
is, it could be quite a wonderful star to pursue with time series during
May-June-July.  We'll try to get something in AZ this week, but of course
are limited to short runs by the sky placement.


                                                  Circular No. 8131
Central Bureau for Astronomical Telegrams
Mailstop 18, Smithsonian Astrophysical Observatory, Cambridge, MA 02138, U.S.A.
IAUSUBS at CFA.HARVARD.EDU or FAX 617-495-7231 (subscriptions)
URL http://cfa-www.harvard.edu/iau/cbat.html  ISSN 0081-0304
Phone 617-495-7440/7244/7444 (for emergency use only)

     M. Orio, Italian National Institute for Astrophysics at Turin,
and University of Wisconsin; E. Leibowitz, Tel Aviv University; and
P. Rodriguez, European Space Agency, report (on behalf of a team
including V. Burwitz, R. Gonzalez-Riestra, Y. Lipkin, J. U. Ness,
S. Starrfield, and M. Still) that V4743 Sgr was observed as a
target-of-opportunity with the XMM-Newton satellite beginning on
Apr. 4.921 UT for about 10 hr:  "The EPIC-pn count rate in 'timing
mode' was 1348.0 +/- 0.3 counts/s in the range 0.2-10 keV.  The
average absorbed flux the range 0.2-2 keV was about 1.5 x 10**-9
erg cm**-2 s**-1, as high as was observed in the first half of the
previous x-ray observation with Chandra (IAUC 8107).  The spectrum
was extremely soft with absorption features, which we attribute to
the central white-dwarf atmosphere.  Preliminary results from the
lightcurve analysis reveal that the peak in the power spectrum
reported on IAUC 8107 is now resolved into two separate peaks, P_1
= 1309.5 s and Q_2 = 1375 s.  The first overtone of P_1 is also
present in the power spectrum.  The period Q_2 seems to be the
first overtone of a fundamental periodicity, P_2 = 2746 s, that
appears significantly in the power spectrum, although with much
smaller power.  A third period, P_3 = 1656 s, is probably also
present.  Despite variability by up to about 20 pecent, the x-ray
flux never decreased to the level observed at the end of the recent
Chandra observation (IAUC 8107).  If an eclipse caused the
obscuration observed with Chandra, the orbital period must be
longer than 10 hr.  We urge optical photometry to detect the
orbital period, in order to understand the mechanism that obscured
the strongest x-ray source in Mar. 2003."
     CCD V magnitudes measured by J. D. West, Mulvane, KS:  2002
Sept. 24.094 UT, 6.40; 29.073, 7.31; Oct. 21.060, 9.11; 2003 Mar.
21.587, 11.34; 26.574, 11.48; Apr. 4.573, 11.54; 5.570, 11.58;
7.538, 11.49; 9.528, 11.54; 14.523, 11.54; 17.530, 11.69; 21.419,
11.62; 26.553, 11.34; 29.428, 11.68.

                      (C) Copyright 2003 CBAT
2003 May 12                    (8131)            Daniel W. E. Green

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