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\begin{center}
\large A CATALOG OF SPECTROSCOPICALLY IDENTIFIED WHITE
DWARFS
\end{center}
\normalsize
\begin{center}GEORGE P. MCCOOK and EDWARD M. SION\\
Department of Astronomy and Astrophysics, Villanova University
\end{center}

\begin{abstract}

A catalog of 2249 white dwarfs which have been identified
spectroscopically is presented complete through 1996 April.  This
compilation is the fourth edition of the Villanova {\it Catalog of
Spectroscopically Identified White Dwarfs}.  For each degenerate star,
the following data entries with references are provided: (1) a catalog
coordinate designation or WD number, in order of right ascension; (2)
the right ascension and declination for epoch 1950.0; (3) the spectral
type based upon the new system;(4) a catalog symbol denoting  binary
membership; (5) a list of most names known to exist for a given star;
(6) proper motion and position angle; (7) broad-band {\it UBV}\
photometry, {\it V, B-V, U-B}; (8) multichannel spectrophotometry, {\it
V(MC), g-r}; (9) Str\"{o}mgren narrow-band photometry {\it y, b-y,
u-b}; (10) an absolute visual magnitude based upon the best available
color-magnitude calibration or trigonometric parallax; (11) the observed
radial velocity uncorrected for gravitational redshift or solar motion;
and (12) the trigonometric parallax with mean error when available.  A
Notes section for unusual or peculiar stars and a coded Reference Key
alphabetized by the first author's last name are presented, as well as
an expanded table cross-referencing all names to catalog WD number.  An
introduction and full descriptions of the entries are provided in the
text.\end{abstract}


\section{INTRODUCTION}

The first edition of this catalog was published privately in 1977 May
(McCook \& Sion 1977) as {\it Villanova University Observatory
Contribution No. 2} and contained less than 600 degenerate stars.  The
preface to that edition provided a succinct rationale of our motivation
for preparing the catalog and is presented here verbatim:
\medskip

\indent\hang{\it The number of newly discovered white dwarfs has increased substantially
since the appearance of the first comprehensive list by Eggen \&
Greenstein in 1965.  The newly observed objects when added to the
earlier lists comprise a sample approaching six hundred stars.  New
spectroscopic, spectrophotometric and photometric observations are being
obtained by several active groups throughout the world.  The volume of
data is enormous and much of it is dispersed throughout the literature.
Some confusion exists with nomenclature especially regarding multiple
names.  The volume of data and the nature of its accessibility in the
literature strongly suggested the need for a general comprehensive white
dwarf catalogue.  While there is clearly no substitute for using the
primary reference literature, it may prove useful in certain applications
for both observers and theoreticians to have the data collected into one
catalogue.  We apologize in advance for the inevitable errors in a
catalogue of this size and welcome corrections and additions being
brought to our attention for inclusion in possible future editions.}
 \medskip

Since the appearance of the first edition of this catalog (McCook \&
Sion 1977), the number of newly identified spectroscopic degenerates has
more than quadrupled.  Building upon the identification of several
hundred new spectroscopic degenerates with the 5.1 m Hale reflector by
Jesse Greenstein and with the Palomar-Green north galactic pole survey
of hot white dwarfs by Green, Schmidt, \& Liebert (1986), the past two
decades have seen over 1500 new spectroscopically identified white
dwarfs discovered in several large scale color-select, objective prism
and proper motion-selected surveys.  The sources of new degenerates are
principally the following surveys: the APM Proper Motion Project (D.
Evans), the Case Low Dispersion Objective Prism Survey (P.  Pesch, M.
Wagner and co-workers), the Edinburgh-Cape Survey (D.  O'Donoghue,
Kilkenny, Stobie, and co-workers), the EUVE Sample (S.  Bowyer, S. Vennes and
co-workers), the Hamburg-Schmidt Survey (U.  Heber and co-workers), the
HK Objective Prism Survey (T.  Beers and co-workers), the KISO UV-Excess
Survey (G.  Wegner and co-workers), Kitt Peak-Downes Survey (R.  Downes
and co-workers), the Large Bright Quasar Survey (C.  Foltz and
co-workers), Luyten/Giclas Common Proper Motion Binary Survey (T.
Oswalt and co-workers), the Montreal-Cambridge-Tololo Survey (G.
Fontaine, F. Wesemael and co-workers), the Palomar-Green Survey (R.
Green, J.Liebert and co-workers), the ROSAT-detected Sample (M.
Barstow, T. Fleming and co-workers), and the UVX COSMOS Survey (B.
Boyle and co-workers).The specific references to these sources are found
in the Reference Key to Table 3, which appears at the end of the paper.

This enlarged sample of spectroscopically identified degenerates is
accompanied by an expanded database of new photometric colors,
parallaxes, proper motions, and radial velocities, as well as expanded
names entries and notes section.  In addition, a superbly illustrated,
comprehensive spectroscopic atlas of all of the identified types of
white dwarf spectra by Wesemael {\it et al.} 1993 is available for easy
reference to the types of spectra contained in this fourth edition
catalogue.

We have excluded references to finding charts in all previous editions
and continue this practice in the present edition. However, at the time
of this writing, a comprehensive on-line finding chart atlas is in
preparation by Tom Marsh, Chris Moran and collaborators in the United
Kingdom.  Moreover we refer the user to an atlas of finding charts for
EUVE sources published by M. Shara et al. (1997).

\section{Selection of the Data: Entry Changes Since the Third Edition}

As in the first, second and third editions, we have attempted in this
fourth edition to include only white dwarfs with published spectroscopic
identification.  In a very few cases, colors and motions strongly
indicate a white dwarf, but no spectral class has as yet been assigned.
We have included white dwarfs that are components of essentially
noninteracting binaries ({\it e.g.}, Roche lobe-detached, short and
long-period systems) whose detected photospheric spectra are
classifiable.  A few examples illustrate the morphological range of such
binary systems: HZ 9, Sirius B, HZ 43, and the DA component of the
barium star Zeta Cet. We have attempted to include all data published or
released to us in preprint form prior to 1996 April.  On the basis of
input received from colleagues throughout the world, content changes
have been introduced in the fourth edition that we hope will help to
maximize its scientific usefulness.

\subsection{Spectroscopic Classification Modifications}

The revised white dwarf spectral classification system presented by Sion
{\it et al.}\ (1983) and implemented in the third edition (McCook \&
Sion 1987) is presented in table 1.  This system has undergone some
further modifications, discussed most recently by Sion (1996), Wesemael
{\it et al.} (1993) and by Liebert \& Sion (1994) in light of both the
increasing accuracy of derived atmospheric parameters for degenerate
stars and the discovery of degenerate stars in which elements heavier
than helium are the dominant photospheric constituent.  A number of
these modifications were originally discussed by Sion {\it et al.}\
(1983) but never implemented in practice.

\label{table1}
\begin{center}
	\begin{tabular}{|ll|}
	     \multicolumn{2}{c}{{\bf TABLE 1}}\\
	\multicolumn{2}{c}{{\bf DEFINITION OF PRIMARY SPECTRAL SYMBOLS}}\\ \hline\hline
	 Spectral Type         &                      Characteristics\\ \hline
	&\\[-0.05in]
	DA ................... & Only Balmer lines; no He I or metals present\\
	DB ................... &  He I lines; no H or metals present\\
	DC ...................  & Continuous spectrum, no lines deeper than 5\%\\
				&       in any part of the electromagnetic spectrum\\
	DO ...................  & He II strong; He I or H present\\
	DZ .................... &  Metal lines only; no H or He lines\\
	DQ ...................  & Carbon features, either atomic or molecular in\\
				&       any part of the electromagnetic spectrum\\[0.05in]
	 P &-- magnetic white dwarfs with detectable polarization\\
	 H &-- magnetic white dwarfs without detectable polarization\\
	 X &-- peculiar or unclassifiable spectrum\\
	 E &-- emission lines are present          \\
	 ? & -- uncertain assigned classification; a colon (:) may also be used\\
	 V &-- optional symbol to denote variability         \\[0.1in] \hline
	\end{tabular}
\end{center}
\medskip

\subsubsection{Refined (Decimal Half Integer and Double Digit) Temperature
      Indices}

Because of the importance of temperature as a direct luminosity and age indicator
in white dwarfs and the fact that white dwarfs span enormous ranges of
T$_{eff}$ ({\em e.g.,}\ the H-rich white dwarfs span a temperature range
from 170,000K to 4500K!), a temperature index was adopted by Sion {\em
et al.} (1983) defined as $10 \times \theta_{eff}$ ($= 50400/T_{eff}$).
However, the limitations of the temperature index in the Sion {\em et
al.} (1983) system become obvious at the lowest (T$_{eff} < 5040$K) and
highest surface temperatures (T$_{eff} > 50400$K) when it no longer
provides the needed indicial temperature discrimination.  Indeed with
the increasing accuracy of derived white dwarf temperatures (and
gravities) using ever more sophisticated LTE and NLTE synthetic spectra
codes with improved atomic physics, a number of advantageous refinements
to the temperature index suggest themselves (Liebert \& Sion 1994).

The use of a half-integer temperature index for white dwarfs with T$_{eff} <
50,400$K, allows for refined temperature classification with the
possibility of even finer decimal sub-divisions as temperatures become
increasingly more accurate.  Thus for example the DA sequence would
extend from DA.5, DA1, DA1.5, DA2, DA2.5.....DA13.  A DA2 star would
have a temperature in the range 22,400K to 28,800K while a DA2.5 would
have T$_{eff}$ in the range 18,327K to 22,400K.  Similary the sequence of DB
stars would extend from DB2, DB2.5, DB3, DB3.5......  A DB2 star would
have a temperature in the range 22,400K to 28,800K while a DB2.5 would
have T$_{eff}$ in the range 18,327K to 22,400K.  The clear advantage of
a decimal half-integer over  the plus symbol (`` + '') is that
further subdivision is possible as temperatures become even more
accurate.  The temperature index for the coolest degenerates is extended
to double digits down to $\theta = 13$, as originally proposed in Sion
{\it et al.} (1983) and implemented, for example, by Greenstein (1986).
 For the hottest degenerates, we adopt a scheme (Liebert \&
Sion 1994) whereby a zero temperature index is circumvented by opting
for a decimal double digit theta index ($\theta < 1.0$).  Thus, the hottest
white dwarfs (log $g \geq 7$ ) are assigned a temperature index of decimal
9 to decimal 1 (.9 to .1).  For example a degenerate star with T$_{eff} =
50,400$K would have a temperature index of 1.0 while a star with T$_{eff} =
200,000$K (hotter than any presently known degenerate with log $g \geq 7$)
would have a temperature index of .25.  Note that {\it there is never a
zero before the decimal point}.  Its use is prohibited because (a) the
inevitable confusion with the hot primary spectral type of O is avoided
(the distinction between zero and O is no longer obvious in computer
operating systems) and (b) a zero index is unphysical since such an
index can never occur.  The range of temperatures corresponding to each
half-integer spectral index is listed in table 2.
\label{table2}
\begin{center}
\begin{tabular}{|lr@{--}rc|}
 \multicolumn{4}{c}{{\bf  Table 2}}\\\hline\hline
\multicolumn{4}{c}{{\bf TEMPERATURE INDEX RANGES}}\\[0.01in]
\multicolumn{1}{c}{\bf Sp.Type}&\multicolumn{2}{c}{{$T_{eff}$ Range}} (K)
&$\Theta_{eff}$ Range\\[0.01in]\hline
DA.25  &  \multicolumn{1}{l}{200,000}&&\\
DA.5    & \multicolumn{1}{l}{100,800}&&\\
DA1     &  40,320  & 67,200  &    1.25 -  0.75\\
DA1.5   &  28,800 &  40,320   &    1.75 -  1.25\\
DA2     &  22,400 &  28,800   &   2.25 -  1.75\\
DA2.5   &  18,327 &  22,400   &   2.75 -  2.25\\
DA3     &  15,507 &  18,327   &   3.25 -  2.75\\
DA3.5   &  13,340  & 15,507   &   3.75 -  3.25\\
DA4     &  11,860 &  13,340   &   4.25 -  3.75\\
DA4.5   &  10,610 &  11,860   &   4.75 -  4.25\\
DA5     &   9,600 &  10,610   &   5.25 -  4.75\\
DA5.5   &   7,467 &   9,600   &   6.75 -  9.25\\
DA6     &   6,952  &  7,467   &   7.25 -  6.75\\
DA6.5   &   6,503 &   6,952    &  7.75 -  7.25\\
DA7     &   6,109  &  6,503   &   8.25 -  7.75\\
DA7.5   &   5,760 &   6,109   &   8.75 -  8.25\\
DA8     &   5,448  &  5,760   &   9.25 -  8.75\\
DA8.5   &   5,169 &   5,448   &   9.75 -  9.25\\
DA9     &   4,917 &   5,169   &  10.25 -  9.75\\
DA9.5   &   4,688  &  4,917   &  10.75 - 10.25\\
DA10    &   4,480 &   4,688   &  11.25 - 10.75\\
DA10.5  &   4,289 &   4,480   &  11.75 - 11.25\\
DA11     &  4,114  &  4,289   &  12.25 - 11.75\\
DA11.5  &   3,952  &  4,114    & 12.75 - 12.25\\
DA12     &  3,803  &  3,952   &  13.25 - 12.75\\
DA12.5  &   3,665 &   3,803   &  13.75 - 13.25\\
DA13     &  3,537  &  3,665   &  14.25 - 13.75\\ \hline\hline
\end{tabular}
\end{center}


\subsubsection {Symbols for White Dwarfs with Extreme Surface Gravity}

We have introduced optional symbols for white dwarfs showing very
diffuse, broad lines corresponding to exceptionally high gravity (log $g\stackrel{
>}{\sim} 9$) and white dwarfs with narrow sharp lines of exceptionally low
gravity (log $g \stackrel{<}{\sim} 7$).  The former are denoted by a lower case {\bf d} for
diffuse, broad lines while the latter are denoted by lower case {\bf n} for
sharp, narrow lines.  These symbols should be assigned only where
spectroscopic or dynamical gravity determinations are ironclad
indicators of extremely high or extremely low gravity.

\subsubsection{ Classification of the Hottest Non-DA Stars}

The hottest non-DA stars present problematic classification because (1)
many are planetary nebula nuclei and isolated post-AGB stars sharing the
hallmark spectroscopic characteristics of the PG1159 degenerates but
their gravities are lower than log $g = 7$ which is traditionally adopted
as the minimum defining gravity for classification as a white dwarf star
(versus a high gravity subdwarf; Greenstein \& Sargent 1974) and; (2)
the assignment of the primary spectral class for a white dwarf is
determined by the element represented by the strongest absorption
features in the optical spectrum.  However, by this criterion, PG1159
stars, for which either oxygen ({\em e.g.,}\ O VI) or carbon ({\em
e.g.,}\ C IV) are the strongest optical lines (with He II features
weaker), should be classified DZQO or DQZO depending upon whether O VI
or C IV are strongest, respectively.  Since many of these objects have
atmospheric compositions which are {\it not} helium-dominated (cf.,  Werner \&
Heber 1992), it is inappropriate to assign spectral type DO on the Sion
{\it et al.} (1983) scheme since the primary O-symbol denotes a
helium-dominated composition.  Here we adopt the primary spectroscopic
type as the atom or ion with the strongest absorption features in the
optical spectrum, where applicable (for example, it is possible that the
strongest absorption feature may lie in the space ultraviolet).  This
scheme for classifying the hottest degenerates preserves consistency
with the original classifications of white dwarf spectra, which have
been based upon what absorption features are actually seen in the
optical spectra (cf.  Greenstein 1960; Sion {\it et al.} 1983).

In this edition we have withheld a degenerate classification for any
PG1159 star with log $g < 7$.  However, these objects are designated
PG1159 in the spectral class entry and the types, as given by Werner
\& Heber (1992) and subsequently used by Dreizler, Werner \& Heber
(1995)
and Napiwotzski \& Schonberner (1991), are given in the notes section of
this catalog.  These designations are: E for emission, lgE for low
gravity, A for absorption, Ep for emission/peculiar, EH, lgEH or AH for
hybrid PG1159s which have detected H.

The temperature index would differentiate the hot C-He-O stars from the
well-known, very much cooler DZ and DQ degenerates below 10,000K. The
temperature index of the PG1159 stars would be (as for all white dwarfs)
given by $10\times \theta_{eff}$ (=50400/T$_{eff}$).  For example PG1159
itself (Log $g = 7$, T$_{eff} = 110,000$K, C IV absorption strongest
optical lines) would be classified DQZO.4.  The obvious disadvantage is
the inevitable confusion with the cool DQ and DZ degenerates in cases
where the temperature index is missing or there are no He II absorption
features ({\em e.g.,}\ H1504).  In a case like H1504 where no helium is
detected and T$_{eff} = 170,000$K, log $g = 7$, our classification scheme
would assign a spectral class DZQ.3.


\subsubsection{Binary Membership Designation}

All binary systems containing one or two degenerate stars (and
essentially non-interacting), regardless of orbital separation, are
denoted by lower case "b" in the column just preceding the start of the
reference number of the spectral type assignment.  Thus these would
range from very close non-interacting pairs ({\it e.g.,} pre-cataclysmics) to
common proper motion systems containing white dwarfs and having no
measurable orbital motion.

%\sub
\subsection{Color-T$_{eff}$ Relations and Color-Absolute Magnitude Correlations}

The color-effective temperature relations are the same as those employed
by McCook \& Sion (1987), which were adopted from Shipman (1979).
Temperature-color index correlations using model atmospheres for DA and
non-DA stars are available for multichannel spectrophotometric colors
 {\it g-r}; Str\"{o}mgren colors ({\it u-b, b-y}); and broad-band {\it UBV} colors ({\it B-V,
U-B}).  Temperatures derived from different model atmosphere grids are
generally very consistent.  We determine the temperature index by using
the color transformations based upon Tables 1 and 2 and equations (9)
and (10) of Shipman (1979).  The transformation relations for non-DA
stars are:
\begin{center}
\((B-V) = 0.334 + 0.836(g-r)\),\\
\((b-y) = 0.286 + 0.553(g-r)\).
\end{center}


\noindent
For DA stars the color transformations are
\begin{center}
\((B-V) = 0.3336 + 0.5906(g-r)\),
\((b-y) = 0.2197 + 0.4486(g-r)\).
\end{center}

\noindent
Similarly, the color-absolute magnitude correlations are presented in
McCook \& Sion (1987) are adopted in this edition.  The original
references to these calibrations are Green (1977), Greenstein (1984),
Sion \& Liebert (1977), and Dahn {\it et al.} (1982).  The same priortized
system of photometric parallaxes adopted by McCook \& Sion (1987) is
used in this edition, including the use of trigonometric parallax when
multiple values of the parallax yield a mean $> 0.100$ arc-seconds.
An absolute visual magnitude has been computed for each star with
measured colors or trigonometric parallax according to the
system described below.  Exceptions to this system are denoted
with numerical codes (0), (5), (6), (7), (8) and (9) and are also
described below. If
measured colors do not exist, an absolute magnitude was not given.  For
all spectral types with ({\it g-r}) color index the following calibration
formula due to Greenstein (1984) was employed:
\begin{center}
\(M_{v} = 13.033 + 3.114(g-r) - 0.799(g-r)^{2}\).
\end{center}

\noindent
For all spectral types with ({\it b-y}) color index, the following calibration
due to Green (1977) was adopted:
\begin{center}
\(M_{v} = 7.56(b-y)+11.50\).
\end{center}

\noindent
The broad-band calibrations are those of Sion and Liebert (1977).  For
DA white dwarfs with $B-V < 0.4$,
\begin{center}
\(M_{v} = 11.246(B-V+1)^{0.60}-0.045\).
\end{center}
\noindent For non-DA stars with $B-V<0.4$,\\
\begin{center}
\(M_{v} = 11.916(B-V+1)^{0.44}-0.011\).
\end{center}

\noindent
If $B-V\geq0.4$, we used the following color-magnitude calibration due to
Dahn {\it et al.}  (1982):
\begin{center}
\(M_{v} = (11.43\pm0.16)+(7.25\pm0.75)(B-V)-(3.42\pm0.68)(B-V)^{2}\).
\end{center}

The color-magnitude relations defined above are fairly accurate and are
the same as we used in the third edition. However, other relations based
upon color-magnitude predictions from model atmospheres (and fitting the
observed data) are even more accurate. In particular we refer the
user to Bergeron, Wesemael and Beauchamp (1995).

In a few cases where three or more measured parallaxes from different
sources are in agreement, exceptions were made to the priority system
above.  Likewise, for degenerate stars whose spectra exhibit abnormally
strong or peculiar blanketing ({\it e.g.}, G 47-18, GD 229, LP 701-29)
and for every cool white dwarfs ({\it e.g.}, LP 131-66), the above
priority system was not followed.  Since for cool white dwarfs the blue
colors ({\it e.g., B-V, b-y, g-r}) yield less accurate photometric
parallaxes than the red colors ({\it e.g., V-I, R-I}), we have adopted
absolute magnitudes from four sources: (a) the tabulation of cool white
dwarfs by
Liebert, Dahn, \& Monet (1987) if our values differed by more than 0.3
mag from theirs; (b) the extensive compilation of absolute magnitudes
for cool
white dwarfs by Bergeron, Ruiz and Leggett (1997); (c) the values for Palomar
-Green DA stars utilized
Liebert et al. (1997) and; (d) the
compilation of absolute magnitudes for the subset of common proper
motion binaries containing white dwarfs which were used to derive
the white dwarf luminosity function in the dissertation by Smith
(1998). The absolute magnitude values from these three are
denoted by numerical codes (6), for Liebert, Dahn and Monet
(1987), (7) for Bergeron, Ruiz and Leggett, and (8) for Liebert et al.
1997, and (9) the values in Smith's (1998) Ph.D thesis.
 An extensive tabulation of red colors of white
dwarfs can be found in a review by Eggen (1985 and references therein),
while {\it V-I}\ color indices are available from the US Naval Observatory
faint star parallax lists cited in this catalog.  Likewise, for the
very hot DA stars where the blue-sensitive color-magnitude calibrations
are insensitive to temperature, we have used the values of $M_{v}$ derived
from actual effective temperature determinations as given, for example,
by Fleming, Green, \& Liebert (1986) and Holberg, Wesemael, \& Basile
(1986).  Here again, however, their values were adopted only if a
discrepancy greater than 0.3 mag existed.  These values are denoted by
numerical code (0).  For the hottest helium-rich degenerates the
photometric parallaxes are grossly inaccurate.  For the DO and DOZ white
dwarfs, we have replaced the $M_{v}$-value with the directly derivable
effective temperature in degrees Kelvin. Most of the adopted values
were
from Wesemael, Green, \& Liebert (1985), Werner \& Heber (1992), Dreizler
et al. (1995) and Napiwotzki and Schonberner (1991), and are indicated
by numerical code (5).  A discussion of the dispersions and analysis of the
calibrations is given in Sion (1979) and Sion (1984).  The value of
absolute visual magnitude is followed by number 1,2,3,or 4 to indicate
the method of determination; (1) parallax, (2) multichannel color, (3)
Str\"{o}mgren color, and (4) {\it UBV}\ color, or the value is followed by (0),
(5), (6), (7), (8) and (9) as described earlier.  Stars with hybrid
classifications were generally not assigned a photometric parallax.

The advent of increasingly accurate effective temperatures and gravities
from detailed spectroscopic fits for DA stars (cf., Bergeron, Saffer \&
Liebert 1992; Finley 1993; Kidder 1992) and gravities (Bergeron, Saffer
\& Liebert 1992), for DB stars (Thejll {\it et al.} 1991), and the
coolest non-DA degenerates, has made it possible to re-generate more
precise photometric parallaxes and temperature indices for a large
number of degenerates subject to the following caveat.  Unless the white
dwarf mass is known, there will be a non-negligible uncertainty in the
white dwarf luminosity.  The appropriate reference is given immediately
following the spectral type.  See Table 3 at the end of the paper.

\section{THE ENTRIES IN TABLE 3}

All entries in Table 3 except coordinates, names, and absolute
magnitudes are followed by a reference number in parentheses -- {\it
e.g.}, (41).  The Reference Key, which follows the Notes, can then be
used to identify the source of the catalog entries.

\indent\hang {\bf WD.} -- The first entry contains a ``WD number", a catalog number
containing the first four digits of right ascension followed by the
sign, the first two digits of declination, and third digit in which
minutes of declination have been expressed as a fraction of a degree.
Stars with identical catalog numbers, whether binary or not, have been
distinguished by using the designations .1 and .2 after their respective
catalog numbers.  The same distinction is used for wide binary pairs.
The choice of the WD number format was made with the idea of continuing
expansion of the catalog as data accumulate.

\indent\hang {\bf R.A. DEC.} -- The second entry contains the full right ascension and
declination (1950.0) adopted according to the following order of
priority: Lowell Observatory coordinates,
Luyten Proper Motion Survey coordinates.  For Bruce Proper
Motion Survey stars, the coordinates may refer to epoch and
equinox 1900.0
if no other proper motion name is listed.  In relatively few cases
cooordinates refer to epoch and equinox 2000.0.  These coordinates are
indicated with a ``J" appended to the WD number.

\indent\hang{\bf SPEC.  CLASS.} -- The third entry lists the spectral
type according to the system described by Sion {\it et al.} (1983),
updated with the modifications described in section 2 where a complete
discussion may be found.  The definition of primary spectral symbols is
given in Table 1 according to the Sion { \it et al.} (1983)
classification.  If more than one spectral class assignment has been
made and cited and they are in agreement, the spectral type has been
converted to the new system and is followed by the original
reference(s).  If more than one spectral class has been cited and they
are in disagreement, a spectral type converted to the new system is
given based upon our assessment of the spectral resolution and
instrumental technology involved, but the old spectral types are
retained followed by their references.  In many cases the primary
classification reference has not been listed but may be easily found in
the secondary reference which is given.  A lower case ``b" is inserted
just before the spectral type reference if the white dwarf is a member
of a non-interacting binary (see section 2.1.4).  An asterisk (*) is
inserted if an entry exists in {\it Notes to Table 3} for white dwarfs
of exceptional astrophysical interest.

\indent\hang{\bf NAMES.} -- The fourth entry contains most of the names that exist for
each star.  The names are listed below, with most of their references.
An extensive list of cross-references to the names in Table 3
can be found in Table 4.

\label{table3}
\begin{center}
\begin{tabular}{|lp{0.7\textwidth}|}\hline
BPM: &-- Bruce Proper Motion Survey: see Reference Key  under Luyten.\\
C: Case: &--  Stephenson (1960, 1962).\\
 C120: Cincinnati: &-- Porter,  Yowell, \&  Smith (1930).\\
CSO,CBS: &-- Case Low Dispersion Survey:  Pesch \&  Sanduleak (1983, 1985),\\
&\ \ \  Sanduleak \& Pesch (1984).\\
CTI: &-- CCD Transit:   Kirkpatrick \&  McGraw (1989).\\
DeHt: &-- Planetary nebula name, authors' initials (Dengel {\it et al.}): \\ & \ \ \
 Perek \&  Kohoutek (1967).\\
EC: &-- Edinburgh-Cape Survey: see Reference Key under Stobie {\it et
  al.} and references therein. \\
EG: &-- Eggen-Greenstein: see Reference Key under Eggen \& Greenstein.\\
 EUVE: &-- Newly Identified white dwarf with the Extreme Ultraviolet
         Explorer:\\ & \ \ \ see Reference Key  under Vennes. \\
\ifhtx\else\end{tabular}	% change page only in TeX context
%\end{center}
\newpage
%\begin{center}
\begin{tabular}{|lp{0.7\textwidth}|}\hline\fi
F, Feige: & --   Feige (1958).\\
G, GD, GH: &-- Lowell names: see Reference Key under Giclas.\\
GL: Gliese:& --  Gliese (1957).\\
GR: Greenstein: &-- See Reference Key under Greenstein.\\
GW: Greenwich: &--  Dyson (1914).\\
HaWe: &-- Planetary nebula name, authors' initials,  Acker (1992).\\
HDW:  &-- Planetary nebula name, authors' initials,
 Perek \&  Kohoutek (1967).\\
HE:  &-- Hertzsprung:  Hertzsprung (1918).\\
HE: &-- Hamburg-Schmidt Survey (southern hemisphere).\\
HL: &-- Tonantzintla:   Haro \&  Luyten (1960).\\
HS: &-- Hamburg-Schmidt Objective Prism Survey: see Reference Key\\ &  \ \ \ under
       Heber, Napiwotzski, Jordan, Dreizler.\\
HZ:  &-- Humason-Zwicky:   Humason \&  Zwicky (1947).\\
 IsWe: &-- Planetary nebula name, authors' initials, Acker (1992).\\
IW:  &-- Planetary nebula name, authors' initials,  Acker (1992).\\
K1: &-- Kohoutek (K1\"{A} 16):  Perek \&  Kohoutek (1967).\\
Karpov (K1-K12):  &--  Karpov (1937).\\
KUV:  &-- Kiso: see References under   Kondo {\it et al}. (1982, 1984),\\
& \ \ \   Noguchi {\it et al} (1980).\\
KPD: Kitt Peak-Downes: &--   Downes (1986).\\
L, LB, LP, LDS, LHS, LTT: &-- Luyten names: see Reference Key under Luyten.
 \\
LBQS: &-- The Large Bright Quasar Survey: see Reference Key under Hewett,\\ & \ \ \
          Foltz.\\
M, Mn- : &-- Planetary nebulae,  Minkowski (1948), Acker (1992).\\
MCT: &-- Montreal-Cambridge-Tololo Survey: see Reference Key under\\ &\ \ \
        Wesemael, Fontaine, Lamontagne.\\
MK: &-- Markarian: see References under  Markarian \& Lipovetski (1971).\\
Other: Other names: &--    Fernandez {\it et al}. (1983).\\
PB:  &-- Palomar-Berger:  Berger \&  Fringant (1977).\\
PG: &-- Palomar-Green: see References under  Green,  Schmidt, \&  Liebert.\\
 PHL: Tonantzintla: &--  Haro \&  Luyten (1962).\\
 R: Ross: &-- Ross (1925-1939).\\
 RB, RWT:& -- Rubin:    Rubin,Westphal, \&  Tuve (1974).\\
 RE: &-- ROSAT Wide Field Camera Survey: see Reference Key under Barstow.\\
 SA: &-- Basle Halo Program:   Steppe (1978).\\
 SB: &--  see References under  Slettebak \&  Brundage (1971).\\
 TC, TON, TPS, TS: & --  Tonantzintla:   Iriarte \&  Chavira (1957),  Chavira (1959),\\ &   \ \ \
Philip \&
Sanduleak (1968).\\
 US: Usher: &--   Usher (1981).\\
VB: Van Biesbroeck: & -- Van Biesbroeck (1961).\\
 V Ma: Van Maanen: & --   Van Maanen (1938).\\
 VR: Van Rhijn-Raimond: &--  Van Rhijn \&  Raimond (1934).\\
 W: Wolf:  &--  Wolf (1919-1929).\\
\end{tabular}
\end{center}

\indent\hang WIDE BAND. -- ({\it V, B-V, U-B}).  The fifth entry contains published values
of wide-band {\it UBV} photometry.  The {\it V}-magnitude is listed followed by {\it B-V,
U-B}, and the reference number.  If the star has not been observed on the
{\it UBV} system, a photographic magnitude and color class (CC) is given from
either the Lowell or Luyten Proper Motion Survey.  Photographic
magnitudes are indicated by a PG following the magnitude in the V
column.


\indent\hang MC ({\it V, g-r}).
  -- The sixth entry contains multichannel spectrophotometric
observations.  The multichannel {\it V}-magnitude is listed, followed by
multichannel color and the reference.

\indent\hang STR\"{O}MGREN ({\it y, b-y, u-b}). -- The seventh entry lists the Str\"{o}mgren,
narrow-band, photometry, {\it y, b-y, u-b}, and the reference.

\indent\hang ABS. MAG. -- The eighth entry lists the absolute visual magnitude
computed from either trigonometric parallax, measured colors, or taken
from
published compilations based upon red photometry. Note that in the case
of DO,
DOZ and PG1159 stars, the absolute magnitude is replaced by a
spectroscopically
determined Teff. The absolute magnitude entry is followed by
a single digit numerical code to indicate the method of calculation or
the source: (1) trigonometric parallax $>0\stackrel{"}{.}1$, (2)
multichannel spectrophotometric colors, (3) Str\"{o}mgren narrow-band
colors, (4) {\it UBV} photometry, (5) Teff value from Wesemael, Green
and Liebert (1985), Werner and Heber (1992), Dreizler et al. (1995), or
Napiwotzki \& Schonberner (1991),
(6) Liebert, Dahn and
Monet (1988), (7) Bergeron, Ruiz and Leggett (1997), (8) Liebert et al.
1997, and (9) Smith (1998).

\indent\hang MU, THETA -- The ninth entry contains the published values
of proper
motion and position angle followed by the reference.  The units are
seconds of arc per annum for proper motion, and degrees for the position
angle.

\indent\hang VRO. -- The tenth entry lists the observed radial velocity uncorrected
for solar motion and gravitational redshift and followed by the
reference.

\indent\hang PI, ME. -- The final catalog entry lists the published
values of the
trigonometric parallax in seconds of arc.  In most cases the parallax is
followed by the reported mean error in units of 0.001.

\bigskip

We are deeply indebted to the following colleagues for communicating
survey data in advance of publication, providing updated or revised
spectral types or other crucial information needed for the production of
this edition: Martin Barstow, Pierre Bergeron, Paul Bradley, Conard
Dahn, Gilles Fontaine, Uli Heber, Jay Holberg, R. Lamontagne, Barry
Lasker, Jim Liebert, Terry Oswalt, Darragh O'Donoghue, Rex Saffer, Gary
Schmidt, Allyn Smith, Richard Tweedy, Bill van Altena, Stephane Vennes,
Volker Weidemann, Klaus Werner, and Francois Wesemael.  At Villanova it
is a pleasure to thank Samir Bham, David Steelman, Srinivas Narendula,
Shami Reddy, Gopi Gopivallabha, Radhika Krishnan, Kunegunda Belle, Qing
Sung, Rick Wasatonic  and Mai Huang for their patient and careful
assistance with data
compilation and proofreading.  We gratefully acknowledge the support of
the National Science Foundation through grants AST88-17172 and
AST90-16283. \medskip

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