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\IBVShead{5032}{16 February 2001}

\IBVStitle{EUVE J0854+390: a New Cataclysmic Variable}


\IBVSauth{Christian, D.J.$^1$; Craig, N.$^2$; Dupuis, J.$^2$; Roberts, B.$^3$}

\IBVSinst{Computer Sciences Corporation/Space Telescope Science Institute, Baltimore, MD, e-mail: dchrist@stsci.edu}
\IBVSinst{ University of California, Berkeley, Space Sciences Lab, e-mails: ncraig@ssl.berkeley.edu,\\ \indent jdupuis@cea.berkeley.edu}
\IBVSinst{FUSE/Johns Hopkins University, Baltimore, MD, e-mail: broberts@pha.jhu.edu}

\SIMBADobj{EUVE J0854+39.0}
\IBVStyp{ CV }
\IBVSkey{Spectroscopy}
\IBVSabs{We report the identification of a new CV in the field of EUVE J0854+390.}
\IBVSabs{The optical spectra show Balmer, He I and He II lines strongly in}
\IBVSabs{emission and indicates the source is a CV, probably magnetic.}

\begintext

We report the identification of a new Cataclysmic Variable (CV) in the
field of EUVE J0854+390. EUVE J0854+390 was detected in the Extreme
Ultraviolet Explorer (EUVE) all-sky survey (Bowyer et al.\ 1996) at 30
cts/ksec in the 100 {\AA} bandpass and reported in the Lampton et al.\
1997 catalog of fainter EUVE sources with ROSAT detections. Follow-up
optical observations of the class of unidentified EUVE all-sky survey
sources (``NOID's'') has previously had success in finding cataclysmic
variables (e.g.\ EUVE J1429-38.0, Craig et al.\ 1995, 1996, \& EUVE
J2115-586, Craig et al.\ 1996; Vennes et al.\ 1996). We observed the
field centered on the EUVE position of EUVE J0854+390 on 18 February
1997 as part of our EUVE NOID optical identification program with the
Lick Shane 3-meter telescope and Kast spectrograph. The Kast is a
double spectrograph with a blue side covering the wavelength region of
3600--5250~\AA\ and $\approx5500$--7500~\AA\ on the red side. This
setup yields a spectral resolution of 1.7~\AA/pixel.

There were three exposures of the CV, starting at 10:04 UT on Feb 18,
1997 and these are summarized in the observing log in Table 1. %For
two of the exposures the slit was centered on other stars in the %field
and the exposures were much shorter. %The shorter exposures were the
result of spectra centered on other objects %in the field, but the CV
was also in the slit. The optical spectra of EUVE J0854+390 showed
Balmer, He I (4471, 5876 \AA) and He II (4686 \AA) lines strongly
in emission with the continuum increasing toward the blue and
indicating the source is a CV, probably magnetic. The first 25 minute
exposure found the lines to be blue-shifted by $\approx200$ km/s and
was followed by a 60-minute exposure. This second observation found the
source to be $\approx2$ times brighter and with the emission lines
shifted to the red. The average line shift was about $\approx6$ \AA\ or
$\approx400$ km/s. The third exposure, started at 11:45 UT, found the
source to be $\approx7$ times fainter than the previous exposure with
lines red-shifted by $\approx100$ km/s, although limited by low
signal. The measured radial velocities suggest the source period is
less than 2 hours, although the poor sampling is not definitive, and
further observations are needed. We show the two brightest optical
spectra of EUVE J0854+390 from 18 February 1997 in Figure~1.

For the brightest spectrum we derived $B$ magnitude of 16.4 for
EUVE~J0854+390 using spectrophotometry. The optical position derived
from the Digitized Sky survey plate (see Figure~2) is: R.A.
08\hr54\mm14\fsec2, Dec.\ +39\deg05\arcm39\farcs6 (J2000) placing it
about 15\arcs\ from the EUVE and ROSAT (1RXS J085413.1+390543) source
positions. Follow-up observations are encouraged.

\IBVSfig{9.35cm}{5032-f1.ps}{Kast blue-side spectra for CV EUVE
J0854+390. The bottom spectrum was the first 30-minute exposure (10:04
UT) and was followed by an hour integration started 34 minutes later
(10:38~UT). The second exposure found the source to be $\approx$2 times
brighter with lines \break red-shifted by $\approx6$~\AA}

\IBVSfig{9.35cm}{5032-f2.ps}{Optical finding chart ($6\arcm\times 6\arcm$)
from the Digitized Sky Survey centered on the EUVE position from
Lampton et al.\ (1997).  The arrow indicates the CV\@. EUVE/ROSAT pointing
uncertainty is indicated with a circle with a radius of 30\arcs.
North is up and east to the left}

\begin{table}
\normalsize
\caption{Optical observing log}
\begin{center}
\begin{tabular}{lllccc}
\hline
\lower6pt\hbox{Source} & \lower6pt\hbox{R.A.$_{\rm opt}$} & \lower6pt\hbox{Dec.$_{\rm opt}$} & Observation & Exposure & \lower6pt\hbox{Air mass} \\[-4pt]
 & & & date & (sec) & \\
\hline
EUVE J0854+390 &08\hr54\mm14\fsec2 & +39\deg05\arcm39\farcs6 & 18 Feb 97 10:04 UT & 1500 & 1.21 \\
 & & & 18 Feb 97 10:38 UT & 3600 & 1.32 \\
 & & & 18 Feb 97 11:45 UT& 1800 & 1.68 \\
\hline
\end{tabular}
\end{center}
\end{table}

\references

Bowyer, S., Lampton, M., Lewis, J., Wu, X., Jelinsky, P., \& Malina, R.F., 1996, {\it ApJS}, {\bf 102}, 129 % \BIBCODE{1996ApJS..102..129B}

Craig, N., Howell, S.B., Sirk, M.M., Malina, R.F., 1996, {\it ApJ}, {\bf 457}, L91 % \BIBCODE{1996ApJ...457L..91C}

Craig, N., Oliversen, R., 1995 {\it IAUC}, No.\ 6201 \BIBCODE{1995IAUC.6201....1C}

Craig, N., 1996 {\it IAUC}, No.\ 6297 \BIBCODE{1996IAUC.6297....2C}

Lampton, M., Lieu, R., Schmitt, J.H.M.M. Bowyer, S., Voges, W.,
Lewis, J., \& Wu, X., 1997, {\it ApJS}, {\bf 108}, 545 % \BIBCODE{1997ApJS..108..545L}

Vennes, S. et al., 1996, {\it AJ}, {\bf 112}, 2254 % \BIBCODE{1996AJ....112.2254V}

\endreferences

\end{document}

