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IAUC 6872: XTE J0421+560, CI Cam; Corrs

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                                                 Circular No. 6872
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)


XTE J0421+560 AND CI CAMELOPARDALIS
     R. M. Hjellming and A. J. Mioduszewski, National Radio
Astronomy Observatory, report:  "VLA images obtained on Apr. 5.08
and 6.94 UT at 22.5 GHz show that the CI Cam radio source had
become resolved.  The extended emission was just becoming apparent
on Apr. 5.08, and by Apr. 6.94 it had the appearance of a roughly
symmetrical S-shaped twin-jet, strikingly similar to the radio jets
of V1343 Aql = SS 433.  The outermost pair of emission components
was separated by about 0".33 on Apr. 6.94; so if one assumes a
beginning at the start of the x-ray outburst on Mar. 31.6, the
proper motion of each component is 26 mas/day.  Assuming a distance
of 1 kpc (Chkhikvadze 1970, as quoted by Bergner et al. 1995, A.Ap.
Suppl. 112, 221), this corresponds to apparent tangential
velocities of 0.15c.  The values of proper motion and apparent
tangential velocity may be larger if jet ejection occured after the
beginning of the x-ray outburst.  Better constraints on these
values will be obtained after analysis of a series of images.  The
presence of relativistic jets from CI Cam supports its
identification with XTE J0421+560."
     Y. Ueda, M. Ishida, H. Inoue, and T. Dotani, Institute of
Space and Astronautical Science; W. H. G. Lewin, Massachusetts
Institute of Technology; and J. Greiner, Astrophysical Institute,
Potsdam, report:  "XTE J0421+560 was observed with ASCA from Apr.
3.31 through 4.14 UT (net exposure 39~000 s).  The source was
detected at R.A. = 4h19m41s, Decl. = +56o00'.2 (equinox 2000; error
radius 0'.5), which is consistent with the VLA determination (IAUC
6857).  The mean flux of the source was 9 x 10E-10 erg sE-1 cmE-2
(2-10 keV), corresponding to about 40 mCrab.  The source flux
showed a gradual decrease during the observation (e-folding decay
timescale of 32 hr), accompanied by a slight softening of the
energy spectrum.  We detected a prominent iron emission line at
6.7 keV (equivalent width 0.6 keV) indicating a thermal origin of
the x-ray emission.   The overall energy spectrum could be
reproduced by a two-temperature model (5.5 and 0.7 keV) of a
thermal emission from the optically thin plasma."


CORRIGENDA
IAUC 6868, GRB 980329, line 5:  for  (see IAUC 6864) read  [GRB
   Coordinates Network Circular No. 40 (GCN 40; URL given on IAUC
   6864); see also http://gcn.gsfc.nasa.gov/gcn/gcn_main.html]
IAUC 6869, S/1997 U 2, line 7, and IAUC 6870, S/1997 U 1, line 11:
   for  D. Graham  read  D. Groom

                      (C) Copyright 1998 CBAT
1998 April 8                   (6872)            Daniel W. E. Green

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