A Catalog of Spectroscopically Identified White Dwarfs
(McCook and Sion 1987)
Documentation for the Computer-Readable Version
Wayne H. Warren Jr.
Doc. No. NSSDC/WDC-A-R&S 88-15
National Space Science Data Center (NSSDC)/
World Data Center A for Rockets and Satellites (WDC-A-R&S)
National Aeronautics and Space Administration
Goddard Space Flight Center
Greenbelt, MD 20771
The machine-readable version of the catalog, as it is currently being
distributed from the Astronomical Data Center, is described. This catalog is a compilation of 1279
white dwarfs that been identified spectroscopically up to January 1987. It is
the third edition of the Villanova Catalog of Spectroscopically Identified
White Dwarfs and contains a large collection of basic photometric and
spectroscopic data (with literature references), cross identifications to
alternate designations, and computed absolute visual magnitudes based upon
trigonometric parallaxes or the best available color-magnitude calibration.
The present compilation is an expanded and updated successor to the first
(McCook and Sion 1977) and second (McCook and Sion 1984) editions of the
catalog. Due to the great increase in the number of newly identified
spectroscopic degenerates and the publication of important surveys since the
previous editions, a new catalog was considered appropriate at this time.
Although the third edition does not incorporate a large number of newly
discovered stars, quite a few revisions, corrections, and some additions have
been made. New parallax and photometric data have been included, the
descriptions of the names entries expanded, and the notes section considerably
enlarged. As such, the new catalog provides a valuable addition to the large
number of machine-readable catalogs presently available to the astronomical
This document describes the machine-readable version of A Catalog of Spectroscopically Identified White Dwarfs as it is
currently being distributed from the Astronomical Data Center (ADC). It is intended to enable
users to read and process the computerized catalog without problems and
guesswork, and it should be used only to supplement the information contained
in the published paper. Since there are several important formatting
differences between the published and machine-readable tables, users of the
machine version are encouraged to carefully study the data descriptions in the
following sections of this document before using and interpreting the data.
A copy of this document should be transmitted to any recipient of the
machine-readable catalog originating from the ADC.
1.2 Source Reference
McCook, G. P. and Sion, E. M. 1987, Astrophys. J. Suppl. 65, 603.
2.1 File Summary
The machine version of A Catalog of Spectroscopically Identified White Dwarfs consists of five files. Table t:sumtab
gives the machine-independent file attributes. All logical records are of fixed
length, and if the catalog is received on magnetic tape, it will contain blocks
of fixed length (as noted below) except that the last block of each file may be
short. The second file contains the basic data of the catalog, while succeeding
ones contain textual information to facilitate the use of the catalog data. The
data file is in a multiple-record format per object in order to allow all known
observations of a star to be reported. Although coordinates have been added to
all records, those other than the first for a given object may contain mostly
blank fields except for those that were needed to record particular multiple
observations of the object.
Summary Description of Catalog Files
|A Catalog of Spectroscopically Identified White Dwarfs |
|(McCook and Sion 1987) |
| |Record |Record
|Number of |
|File |Contents |Format |Length
1 |Introduction |Fixed |80 |501 |
|2 |Data |Fixed |188 |2420 |
|3 |Notes |Fixed |80 |200 |
|4 |Names |Fixed |30 |2809 |
|5 |References |Fixed |80 |320 |
The information contained in the above table is sufficient for a user to
describe the indigenous characteristics of the machine-readable version of
A Catalog of Spectroscopically Identified White Dwarfs to a computer. Information easily varied from installation to
installation, such as block size (physical record length), blocking factor
(number of logical records per physical record), total number of blocks,
density, number of tracks and character coding (ASCII, EBCDIC) for tapes, is
not included, but should always accompany secondary copies if any are supplied
to other users or installations.
2.2 Introduction (File 1 of 5)
This file is composed of straight text and contains the introduction to the
published catalog. Column descriptions of catalog data are given here and are
therefore only briefly repeated in this document. A detailed byte-by-byte
description of the data format is not included in this introduction, however,
and is therefore given in the following section of this document.
2.3 Catalog (File 2 of 5)
This file contains the compilation of basic data for the degenerate stars
included in the catalog. General data descriptions and remarks about the data
sources, etc. are given in the introductory file.
As mentioned in Section s:FS, the data file may contain more than one
logical record per object if multiple values of reported data exist. This means
that any data field, except for the WD number and coordinates, may be blank.
Since the ``names'' field contains two subfields, there is space for two
alternate designations before a second record is needed. The inclusion of more
than a single value of any other datum requires that a second or succeeding
record be present. Thus, for example, the object WD0000+171 (the first
degenerate in the catalog) has only a single record, whereas WD0000-170 (the
second object) has four records because four values of the proper motion are
included in the catalog. All of the other fields are not blank, however,
because three alternate identifiers, two UBV values, and two multichannel
spectrophotometric data are included.
Table t:cattab gives a byte-by-byte description of the contents of the
data file. A suggested Fortran format specification for reading each data field
is included and can be modified depending upon individual programming and
processing requirements (Fortran 77 character string-type formats are used);
however, caution is advised when substituting format specifications, since many
data fields contain character data and others are blank when data are absent.
Particular care is required for the photometric data (color indices), proper
motions, and trigonometric parallax, where valid zero values can exist, but
where fields are blank for nonexistent data, and where precision may vary
within the same field. It is safest to buffer in records in an unformatted mode
or read them with character (A) formats and test for blank data fields before
processing with numerical formats for calculations and/or searching purposes.
For such fields, primary numerical format specifications are given to indicate
decimal-point locations, while alternate A-type formats are specified in
parentheses. Default (null) values are always blanks in data fields for which
primary suggested formats are given as A.
Data File Record Format
| |Suggested |Default ||
|Bytes |Units |Format |Value |Data |
1-10 |— |A10 (I4,F6.1) |— |WD number |
|11-13 |hours |I3 |— |Right ascension |
|14-16 |min |I3 |— |RA |
|17-19 |sec |I3 |— |RA |
|20 |— |I1 |— |Coordinate accuracy flag |
|21-23 |deg |I3 |— |Declination |
|24-28 |arcmin |F5.1 |— |Dec |
|29 |— |1X |— |Blank |
|30-35 |— |A6 |— |Spectral type |
|36-39 |— |A4 |— |Spectral-type reference |
|40 |— |1X |— |Blank |
|41-65 |— |A25 |— |Names |
|66-71 |mag |F6.2 (A6) |blank |Visual or photographic magnitude |
|72 |— |A1 |— |Magnitude uncertainty flag (:) |
|73-74 |— |A2 |— |Photographic magnitude designation |
|75-79 |mag |F5.2 (A5) |blank |B-V color |
|80 |— |A1 |— |B-V uncertainty flag (:) |
|81-83 |— |A3 |— |Color class |
|84-88 |mag |F5.2 (A5) |blank |U-B color |
|89 |— |A1 |— |U-B uncertainty flag (:) |
|90-93 |— |A4 |— |Wide-band photometry reference |
|94-95 |— |2X |— |Blank |
|96-100 |mag |F5.2 (A5) |blank |Multichannel V magnitude |
|101 |— |A1 |— |Magnitude uncertainty flag (:) |
|102-107 |mag |F6.2 (A6) |blank |Multichannel g-r color |
|108-111 |— |A4 |— |Spectrophotometric reference |
|112-118 |mag |F7.3 (A7) |blank |V(y) magnitude |
|119-124 |mag |F6.3 (A6) |blank |b-y color |
|125-131 |mag |F7.3 (A7) |blank |u-b color |
|132-135 |— |A4 |— |uvby reference |
|136-137 |— |2X |— |Blank |
|138-142 | |F5.2 (A5) |blank |Absolute visual magnitude |
|143 |— |A1 |— |Absolute visual magnitude code |
|144-146 |— |A3 |— |Absolute visual magnitude reference |
| Units are magnitudes or kelvins (see MV
Data File Record Format (continued)
| |Suggested |Default ||
|Bytes |Units |Format |Value |Data |
147-153 |arcsec |F7.4 (A7) |blank |Annual proper motion |
|154 |— |A1 |— |PM code |
|155-159 |deg |F5.1 (A5) |blank |PM position angle |
|160-163 |— |A4 |— |PM reference |
|164-168 |km/s |I5 |blank |Radial velocity |
|169-170 |— |2X |— |Blank |
|171-174 |— |A4 |— |Radial-velocity reference |
|175-181 |arcsec |F7.4 (A7) |blank |Trigonometric parallax |
|182 |— |A1 |— |Trigonometric parallax code |
|183-184 |0.001 arcsec |I2 |blank |Trigonometric-parallax mean error |
|185-188 |— |A4 |— |Trigonometric-parallax reference |
[WD number] Stars having identical catalog numbers, whether binary or not,
are distinguished by using the designations .1 and .2 in bytes 9-10.
[Coordinate accuracy flag] Specifies the accuracy (and in some cases
precision) to which the equatorial coordinates are given:
 Right ascension given in hours, minutes and seconds; Declination
reported in degrees, arcminutes and tenths.
 RA originally given in hours, minutes and tenths, in which case a
conversion to seconds has been effected in order to make the format uniform. In
some cases, RA may be given to hours and minutes only (bytes 18-19 blank). Dec
is generally given in degrees and whole minutes only (byte 28 blank).
[Equatorial coordinates] Equinox 1950.
[Spectral type] Classification according to the new system described by
Sion et al. (1983). A full description of the notation is given in the
[Spectral-type reference] Coded reference given in the references file
(5). In many cases, the primary classification reference is not given, but may
be found in the secondary reference listed.
[Names] Cross identifiers to the various designations by which each star
is commonly known. A key to the names is given in the introductory file and an
extensive table of cross identifications, ordered alphabetically, is provided
in the NAMES file (4).
[Visual or photographic magnitude] A V magnitude on the UBV
sytem is given where available. If the star has not been observed on the
UBV system, a photographic magnitude may be reported. Precision varies from
whole magnitudes to hundredths for V; it is to tenths only for ptg.
[Magnitude uncertainty flag] A colon (:) denotes an uncertain value.
[Photographic magnitude designation] The characters ``pg'' are present if
the magnitude is photographic.
[B-V color] This field may be blank for succeeding records of the same
object (as can any fields except for the WD identifier and coordinates) or if a
photographic magnitude is reported in bytes 67-71 and a color class is coded in
[B-V uncertainty flag] A colon (:) denotes an uncertain value.
[Color class] A color class from either the Lowell or Luyten proper-motion
surveys is given if only a photographic magnitude is available.
[U-B color] U-B on the Johnson and Morgan UBV system.
[U-B uncertainty flag] A colon (:) denotes an uncertain value.
[Wide-band photometry reference] Coded reference given in the references
[Multichannel V magnitude] V magnitude determined from multichannel
spectrophotometric observations. Precision varies (tenths or hundredths).
[Magnitude uncertainty flag] A colon (:) denotes an uncertain value.
[Multichannel g-r color] Color determined from multichannel
[V(y) magnitude] V as determined from four-color (uvby)
photoelectric observations. In general, this should agree well with the V
magnitude from wide-band photometry. Most values are reported to hundredths,
but a few to thousandths are included.
[b-y color] Values are generally reported to thousandths, but precision
[u-b color] As determined from four-color observations. The u-b
index is computed from the nominal uvby colors c1 and m1 by:
\[(u-b) = c_1 + 2[m_1 + (b-y)]\]
[uvby reference] Coded reference given in the references file (5).
[Absolute visual magnitude MV] MV computed from either a
trigonometric parallax or from measured colors according to the following
[(1)] πtrig > 0.1 arcsec
[(2)] Multichannel spectrophotometric colors
[(3)] uvby colors
[(4)] UBV photometry
Exceptions to this priority system are denoted by the codes (0), (5) and (6)
and are described in the introductory file. A notable exception is present in
the machine version for reference code (5) [see byte 143 explanation].
[MV code] In most cases, data are given in units of magnitudes.
However, for the DO and DOZ white dwarfs, the compilers have replaced MV
values with directly derivable effective temperatures. These are given in bytes
138-142 in units of 105 K in the machine version and are denoted by the
presence of an ``E'' in byte 143. See the introductory file or the published
paper for additional information. A colon for uncertainty in MV can occur
[MV reference] Coded reference given in the references file (5).
[Proper Motion] The annual proper motion is given in seconds of arc and
the precision varies. Estimated proper motions (EPM) are also reported with a
code in byte 154 (see explanation below).
[PM code] In cases where only an EPM is reported in the Lowell
proper-motion surveys, bytes 148-153 are blank and a corresponding code is
given in byte 154. These codes are defined in Giclas et al. (1967, 1970)
and are the following:
 Stars of blue color whose motions are too small to definitely verify
on all plates.
 Estimated proper motion <= 0.1 arcsec.
 Estimated proper motion 0.1 arcsec <= PM < 0.2 arcsec.
 Estimated proper motion 0.2 arcsec <= PM < 0.26 arcsec.
[PM position angle] Position angles are given to varying precision, but
there is always a decimal point in byte 158 in the machine version.
[PM reference] Coded reference given in the references file (5).
[Radial velocity] Observed radial velocity uncorrected for solar motion
and for gravitational redshift.
[Radial-velocity reference] Coded reference given in the references file
[Trigonometric parallax, πtrig] Published values of observed
[Trigonometric parallax code] A colon (:) denotes an uncertain value.
[πtrig mean error] Reported mean errors associated with
[πtrig reference] Coded reference given in the references file
2.4 Notes (File 3 of 5)
This file contains the notes for stars flagged by an asterisk in byte 35 of the
Notes File Record Format
|Bytes |Format |Data |
1-4 |4X |Blank |
|5-16 |A12 |WD number |
|17-18 |2X |Blank |
|19-80 |A62 |Notes |
[WD number] Number of the star in the main data file.
[Notes] Notes in free text (upper case only) form. When bytes 5-16 are
blank, this record continues the remarks for the previous star.
2.5 Names (File 4 of 5)
This file contains an extensive cross-identification table from commonly used
white-dwarf designations to the WD numbers employed in the catalog. The file is
ordered alphabetically and is reasonably uniform within each designation type,
i.e., it can be sorted and resorted by name and the records will emerge
in order by both name and numerical designation. This uniformity was achieved
by allocating the first part of the names field to the alphabetic part of each
designation and the second part to the corresponding number. Component
designations for multiple systems follow the numerical part of a name in a
Names File Record Format
|Bytes |Format |Data |
1-16 |A16 |Name |
|17 |A1 |Component designation |
|18 |1X |Blank |
|19-30 |A12 |WD number |
[Name] The commonly used name for the degenerate.
[Component designation] Identification of the component for a
[WD number] The WD designation used in the catalog.
2.6 References (File 5 of 5)
This file contains the bibliographical references ordered by
the codes used in the data file.
References File Record Format
|Bytes |Format |Data |
1-2 |A2 |Reference code |
|3 |1X |Blank |
|4-80 |A77 |Reference |
[Reference code] A two-character code used in the data file to cite a
[Reference] Reference in free text (upper case only) form. Bytes 1-9 of a
record are blank if it is a continuation of a reference.
3.1 Remarks and Modifications
The machine-readable data files of A Catalog of Spectroscopically Identified White Dwarfs were received on floppy disks
from Dr. George P. McCook of Villanova University on January 20, 1988. The
individual files of the catalog were uploaded to the IBM 3081K computer of the
NASA Space and Earth Sciences Computing Center at Goddard Space Flight Center,
where the data were examined for uniformity, structure, and ease of machine
processing. Based upon this analysis, the following modifications to the data
files were made with the collaboration of the compilers:
- Individual corrections were made to the data file based upon the presence
of certain superfluous characters, data misalignment, and a few erroneous
- The data file was reformatted in order to isolate photographic magnitude
designations, color classes, Teff codes in the MV field, and EPM
codes from their corresponding numerical fields, thus allowing all data to be
read and searched with a uniform format. Color-index data, which can have zero
values, must clearly still be read with a character format and tested for
blanks before data searches can be run, but the present uniformity in format
and coding allows for simplified processing and sorting, etc.
- The original data file had positional data only in the first record of a
group. Right ascension values were also given in different formats (``mm ss''
and ``mm.m''). All data were therefore converted to the ``mm ss'' format and
the coordinate accuracy flags were added between the RA and Dec fields. A
program was then written to transcribe the coordinates from the first record of
each degenerate to all other records for the same object, thus simplifying the
searching and sorting of the data by position.
- Certain data, such as declination, magnitudes, and position angles of
proper motions, were present as both integer and real numbers. Decimal points
were added to all of these, even if there are no fractional units, so that all
data can be processed with a single format specification.
- The names file was structured in a multicolumn format as in the published
catalog. The entire file was reformatted to produce a single record per object
and the name field was expanded to allow for a reasonably uniform format to be
designed and implemented. Names were also converted from all upper to mixed
case, depending upon how they are used in the literature and in the original
Appreciation is expressed to Drs. George P. McCook and Edward M. Sion for
supplying the machine-readable catalog, for collaborating to make the changes
described above, and for reviewing this documentation before its final release.
Dr. Sion's prompt responses by telephone and electronic mail helped greatly to
speed up the completion of the work and thus to make the data available to the
astronomical community sooner.
Giclas, H. L., Burnham, R. Jr., and Thomas, N. G. 1967, Lowell Obs.
Bull. No. 141.
Giclas, H. L., Burnham, R. Jr., and Thomas, N. G. 1970, Lowell Obs.
Bull. No. 153.
McCook, G. P. and Sion, E. M. 1977, A Catalog of Spectroscopically Identified White Dwarfs, 1st edition,
Villanova Univ. Obs. Contrib. No. 2.
McCook, G. P. and Sion, E. M. 1984, A Catalog of Spectroscopically Identified White Dwarfs, 2nd edition,
Villanova Univ. Obs. Contrib. No. 3.