Central Bureau for Astronomical Telegrams
IAUC 6857: XTE J0421+560, CI Cam
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Circular No. 6857
Central Bureau for Astronomical Telegrams
INTERNATIONAL ASTRONOMICAL UNION
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XTE J0421+560 AND CI CAMELOPARDALIS
F. E. Marshall and T. E. Strohmayer, Goddard Space Flight
Center; and W. H. G. Lewin, Massachusetts Institute of Technology,
on behalf of his collaborators, report a new position for XTE
J0421+560 (IAUC 6855) based on multiple scans across the source
with the Proportional Counter Array of RXTE on Apr. 1.3 UT. The
best-fit position is R.A. = 4h19m.6, Decl. = +56o00' (equinox
2000.0), with an estimated error radius (90-percent confidence) of
1'. This is 12' from the previously reported position.
R. M. Hjellming and A. J. Mioduszewski, National Radio
Astronomy Observatory, report: "On Apr. 2.63 UT, a 19-mJy radio
source was observed with the Very Large Array at 1.4 GHz at R.A. =
4h19m42s.05 +/- 0s.03, Decl. = +55o59'58".6 +/- 0".5 (equinox
2000.0). This is inside the RXTE PCA position reported by Marshall
et al. (see above). This source was detected on Apr. 1.9 UT at a
level of about 12 mJy at 1.4 GHz, but with poor flux determination
due to bandwidth smearing and beam degradation, since it was 11'
from the field center. This source was not present in an NVSS
survey image from 1993 Nov. 3 (upper limit of 2 mJy at the same
frequency). Although this source could be the radio counterpart of
XTR J0421+560 if short timescale variability can be established,
R. M. Wagner (see below) has informed us that its position is
coincident with that of the symbiotic star, CI Cam (= MWC 84)."
R. M. Wagner, Ohio State University; and S. G. Starrfield,
Arizona State University, report: "An optical spectrum (range
355-715 nm; resolution 1.4 nm) of CI Cam was obtained on Apr.
3.145 UT with the Perkins 1.8-m telescope and CCD spectrograph.
The spectrum exhibits strong Balmer and He I emission lines, as
well as weaker emission features arising from Fe II. For H-alpha
emission, we find an instrument-corrected FWHM of 610 km/s, a FWZI
of 2900 km/s, and an equivalent width of 32 nm. The H-alpha to
H-beta intensity ratio is 6.4. Our spectrum is similar to that
obtained in Jan. 1984 by Downes (1984, PASP 96, 807) and described
previously by Merrill (1933, Ap.J. 77, 44). However, our spectrum
also exhibits He II emission lines at 468.3 and 541.1 nm, with
equivalent widths of 5.4 and 0.4 nm, respectively. He II emission
lines are not present in the Downes spectrum, nor were they
detected by Merrill. The presence of He II at this time suggests
that CI Cam could be the optical counterpart of XTE J0421+560, in
analogy with the optical spectra of other x-ray sources. Its
appearance could also result from an orbital effect and be
unrelated to the new x-ray source. Continued optical spectroscopy
to monitor the evolution of the spectrum and He II emission is urged."
(C) Copyright 1998 CBAT
1998 April 3 (6857) Daniel W. E. Green
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