Central Bureau for Astronomical Telegrams
IAUC 6862: XTE J0421+560, CI Cam; C/1998 F1
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Circular No. 6862
Central Bureau for Astronomical Telegrams
INTERNATIONAL ASTRONOMICAL UNION
Mailstop 18, Smithsonian Astrophysical Observatory, Cambridge, MA 02138, U.S.A.
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XTE J0421+560 AND CI CAMELOPARDALIS
R. M. Hjellming and A. J. Mioduszewski, National Radio
Astronomy Observatory, report: "Very Large Array observations of
CI Cam on Apr. 3.83 UT reveal the presence of an unresolved point
source with preliminary flux densities of 120, 470, 650, 500, and
420 mJy at 1.4, 4.9, 8.4, 14.9, and 22.5 GHz, respectively. This
indicates that it was optically thick at the two lower frequencies
and close to optically thin at the two higher frequencies. The
size of the source is < 0".1 at 22.5 GHz. We reanalyzed the
1.4-GHz data for Apr. 2.63 (IAUC 6857) and were able also to image
the source at 4.9 and 8.4 GHz, so we can report preliminary flux
densities of 20, 150, and 280 mJy at these three frequencies on
Apr. 2.63; at that time, the spectrum was optically thick, with a
spectral index of about 1.5. The rapid variability of factors of
about 6, about 3, and about 2.3 at 1.4, 4.9, and 8.4 GHz,
respectively, indicates that this is synchrotron radio emission
that is probably related to the x-ray transient XTE J0421+560 (IAUC
6855, 6857). Since the position of the unusual radio source
coincides with the 'symbiotic' star CI Cam, the radio emission and
x-ray transient can both be identified with CI Cam."
E. L. Robinson, W. F. Welsh, M. T. Adams, and M. E. Cornell,
University of Texas and McDonald Observatory, report: "We obtained
a wide-field R-band CCD image of the field of XTE J0421+560 on Apr.
2.1 UT with the Prime Focus Camera on the 0.7-m telescope at
McDonald Observatory. The peculiar variable star CI Cam (= MWC 84),
which is near the center of the XTE error circle and at the
position of the radio source found by Hjellming and Mioduszewski,
was at R about 7.1. According to Bergner et al. (1995, A.Ap. Suppl.
112, 221), the R magnitude of MWC 84 is normally between 10.47 and
10.69. This optical outburst and the emergence of He II emission
lines in its spectrum (Wagner and Starrfield, IAUC 6857) make CI
Cam the probably optical counterpart of XTE J0421+560."
COMET C/1998 F1 (SOHO)
C. St. Cyr, Naval Research Laboratory, on behalf of the
SOHO-LASCO Consortium (cf. IAUC 6685), reports the discovery by D.
Biesecker of a comet in both C3 and C2 coronagraphic data. The
comet was estimated at mag 4, and a tail was clearly visible in the
C2 data. Further details with observations and orbit are given on
MPEC 1998-G11.
1998 UT R.A. (2000) Decl.
Mar. 21.818 0 15.9 - 1 08
(C) Copyright 1998 CBAT
1998 April 4 (6862) Daniel W. E. Green
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