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\newcommand{\euve}{\mbox{\em EUVE\/}}
\def\simlt{\lower.5ex\hbox{\ltsima}}
\def\ltsima{$\;\buildrel<\over\sim\;$}
\begin{document}
 
\title{The Extreme Ultraviolet Explorer \\Bright Source List}
 
\author{Roger~F.~Malina, Herman~L.~Marshall,\footnote{currently at the
Center for Space Research, MIT, 77 Massachusetts Ave., Cambridge, MA
02139}
Behram~Antia, Carol~A.~Christian,
Carl~A.~Dobson,\footnote{currently with Dobson Software
Innovations} 
David~S.~Finley, Antonella~Fruscione, Forrest~R.~Girouard, 
Isabel~Hawkins, Patrick~Jelinsky, James~W.~Lewis, 
J.~S.~McDonald,\footnote{currently with the Department of Astronomy,
San Diego State University, San Diego, CA 92182} 
Kelley~McDonald, Robert~J.~Patterer,\footnote{currently at Hughes
STX, Goddard Space Flight Center} 
Vincent~W.~Saba, Martin~M.~Sirk, Brett~A.~Stroozas,
John~V.~Vallerga, 
Peter~W.~Vedder,\footnote{currently at NASA Headquarters, Code SZ,
Washington, DC 20546}
Alexandria~Wiercigroch, and Stuart~Bowyer~\footnote {also with the
Astronomy 
Department, University of California, Berkeley, CA 94720}}
 
\affil{\it {Center for EUV Astrophysics, 
2150 Kittredge Street, University of California, \\ Berkeley, CA 94720}}

\section*{The Bright Source List}
The following table contains information on the 356 bright extreme
ultraviolet (58--740 \AA) sources detected during the in-orbit
calibration and the survey phase of the Extreme Ultraviolet Explorer
(\euve) mission.  The list includes all bright sources whose existence
was established before April 1993 in the data set obtained from 7 June
1992 to 21 January 1993.  The table is ordered in right ascension, and
it is organized as follows:

{\it Column (1)}.---\euve\ source name as specified by the
International Astronomical Union.  Each source is identified by its
J2000 coordinates in hours and minutes of right ascension and decimal
degrees of declination. Errors in the preliminary Bright Source
List (BSL) names for half a
dozen sources have been corrected.

{\it Columns (2) and (3)}.---Right ascension ({\tt hh:mm:ss}) and
declination ({\tt dd:mm:ss}) of the EUV source in J2000 coordinates.
Positions should be accurate to 60 arcsec at about 90\% confidence.
Less accurate positions ($\sim 90$ arcsec) are available at present
for the few sources detected only in the Dagwood or Sn/SiO filters
(due to unknown boresight errors), and for the sources detected in the
deep survey skymaps.  

{\it Columns (4) and (5)}.---Galactic longitude ({\it l}) and latitude
({\it b}) of the EUV source.

{\it Columns (6), (7), (8) and (9)}.---Count rate, in
counts/kilosecond, for the sources detected in the scanners' Lexan/B,
Al/Ti/C, Dagwood, and tin filters.  The count rates are accurate to
within 50\%, although there are occasional errors of a factor of 2.
Count rates have been rounded to the nearest value in multiples of 10,
except where the rounding would alter the count rate by more than
30\%.  Note that, although all BSL sources have significance 
$\geq 3.2~\sigma$, the list should {\em not\/} be 
considered complete at that
level.

Count rates of calibration sources not scanned during the all-sky
survey (because of gaps, etc.) were measured from the calibration
data, on an orbit-by-orbit basis.  The highest significant value
(i.e., highest signal-to-noise ratio [SNR] and long exposure) has been
quoted in the BSL.  In cases when a calibration source was also
scanned during the survey, the survey measurements have been quoted in
the BSL.  

{\it Columns (10) and (11)}.---Count rate, in counts/kilosecond, for
the sources detected in the Deep Survey Lexan/B (DSL) and Al/C
(DSA) filters. 

{\it Columns (12) and (13)}.---Possible optical counterpart of the EUV
source and alternate name. The candidate counterparts come from a
detailed search of astronomical catalogs, including the SIMBAD and NED 
databases.
We choose the possible counterparts among the sources most likely to emit
EUV radiation, e.g., white dwarfs, active late-type stars, 
cataclysmic variables, and active extragalactic objects in low
hydrogen column density directions (\simlt $2 \times 10^{20}$ cm$^{-2}$).
All counterparts lie within 1.5 arcmin of the \euve\ source position,
except for the deep survey sources, where the most likely candidate
within 3 arcmin of the detected location is listed.  (The rate of
coincidental identification at 3 arcmin for the deep survey sources
was tested by searching for candidates around random positions: only
one ``false'' object out of 28, equal to the total number of deep
survey sources, had a plausible counterpart.)

No detailed nomenclature is given in general for different components
of a same system (e.g., binary systems) and the notation ``NOID'' is
used for currently unidentified sources.  For the purpose of this BSL,
we chose the most likely identification in case the EUV source had
more than one possible optical counterpart: follow-up spectroscopy and
photometry are in progress to identify all the ``NOID'' sources and to
confirm the other identifications. 

{\it Column (14)}.---Source type or spectral type of the
optical candidate for the EUV source. Spectral types generally come
from the SIMBAD database and follow the SIMBAD spectral type coding
(see Appendix D of the SIMBAD User's Guide and Reference Manual).  
Extragalactic source types are from NED.
Some of the white dwarfs spectral types were provided by Finley (1993,
private communication).
The notation ``CSPN'' indicates the central star of a planetary nebula,
``XRB'' an X-ray binary system, and ``LMXB'' a low mass X-ray binary.
Table 4 is a breakdown of the BSL sources by spectral type.

{\it Column (15)}.---Visual magnitude of the optical counterpart.
The measurements generally come from the variety of catalogs included in
SIMBAD and NED databases and therefore should be considered only as a
rough indication. 

{\it Column (16)}.---Where applicable, the name of the EUV source as
it appears in the {\it ROSAT\/} WFC Bright Source Catalogue (Pounds et
al.\ 1993).
\euve\ and \it ROSAT\/ \rm
sources are considered identical if they lie within 1.5 arcmin of one
another.

{\it Column (17)}.---General notes and/or comments about 
specific EUV sources (e.g., which sources were calibration targets); all 
notes are explained at the end of the Table.

\end{document}
