AN ATLAS OF OPTICAL SPECTROPHOTOMETRY OF WOLF-RAYET CARBON AND OXYGEN STARS
(Torres and Massey 1987)
Documentation for the Machine-Readable Version
January 1989
Lee E. Brotzman
Contract NAS 5-28752
Prepared for
National Aeronautics ans Space Administration
Goddard Space Flight Center
Greenbelt, MD 20771
Prepared by
ST Systems Corporation
4400 Forbes Blvd.
Lanham, MD 20706
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Abstract
This document describes the computer-readable version of "An Atlas of
Optical Spectrophotometry of Wolf-Rayet Carbon and Oxygen Stars" (Torres
and Massey 1987) distributed by the Astronomical Data Center, NASA
Goddard Space Flight Center. This catalog contains a homogeneous set of
optical spectrophotometric observations (3300-7300 A) at moderate
resolution (~ 10 A) of almost all WC and WO stars in the Galaxy, the
LMC, and the SMC. A header record for each set of spectrophotometric
data contains identification(s), type, instrument, number of data
points, and comments. Following each header, data records contain the
wavelength, flux (f_lambda), and magnitude (m_v) for five data points.
The present document describes the structure of the catalog file
overall and the individual data fields in detail.
1.0 INTRODUCTION
A copy of this document should be distributed with every copy of the
machine-readable catalog.
1.1 DESCRIPTION
An Atlas of Optical Spectrophotometry of Wolf-Rayet Carbon and Oxygen
Stars (WRCOS; Torres and Massey 1987) contains a homogeneous set of
optical spectrophotometric observations (3300-7300 A) at moderate
resolution (10 A) of almost all WC and WO stars in the Galaxy, the
LMC, and the SMC. The data for each observation of a Wolf-Rayet star are
presented as a header record and several data records. Each header
record contains a primary identification, secondary identification(s),
spectral type, the observing instrument name, the number of data points,
and comments. Each data record contains wavelength, flux (f_lambda), and
magnitude (m_v) measurements for five data points. The number of data
records for each observation depends on the number of data points listed
in the header record.
1.2 REFERENCE
Torres, A. V. and Massey, P. 1987, An Atlas of Optical Spectrophotometry
of Wolf-Rayet Carbon and Oxygen Stars, Ap. J. Supp., 65, 459.
2.0 STRUCTURE
2.1 THE FILE AS A WHOLE
The WRCOS consists of one file. Table 1 gives the machine-independent
attributes. All records are of fixed length. The catalog file contains
the header records and flux data for all the stars in the atlas (Table 2
and Table 3). A detailed description of the file is given in the section
below.
Quotations in any of the following descriptions come from Torres and
Massey 1987 unless otherwise noted.
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An Atlas of Optical Spectrophotometry of
Wolf-Rayet Carbon and Oxygen Stars (WRCOS)
File Contents Record Logical Record Total Number of
Format Length Logical Records
1 Atlas FB 140 21535
FB = Fixed-Block Format
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Table 1. Summary Description of Catalog Files
2.2 HEADER RECORDS
Header records are used to separate the spectrophotometric data for
successive stars. They can be distinguished from data records by
inspecting byte 1, which is always non-blank for header records and
always blank for data records. The header records, which contain
descriptive information about the object observed, follow the same
format for every star.
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Bytes FORTRAN Format Data Name
1- 8 A8 Identification
9-28 A20 Other name(s)
29-31 A3 Spectral type
32 A1 Absorption line flag
33 lX Blank
34-36 A3 Instrument code
37-42 I6 Number of data points
43 1X Blank
44-113 A70 Comment
114-140 27X Blank
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Table 2. Header Record Format
Identification WR numbers are from van der Hucht et al. (1981). BR
numbers are from the compilation of W-R stars in the
LMC (Breysacher 1981). Sk 188 is in the SMC (Azzopardi
and Breysacher 1979). [bytes 1-8, format A8]
Other name(s) [bytes 9-28, format A20]
Spectral type From Torres, Conti, and Massey (1986). [bytes 29-31,
format A3]
Absorption line flag A plus sign, "+", if the star shows absorption lines
in its spectrum, otherwise blank. [byte 32, format A1]
Instrument code One of the following:
IRS
The Intensified Reticon Scanner on the white
spectrograph at the No.1 0.9-m telescope at
Kitt Peak. The IRS detector package consists of
an ITT proximity-focused image tube followed by
a micro-channel inverter image intensifier and a
dual Reticon array of 936 pixels with a fiber
optic window. Only 820 pixels are usable because
of distortion and vignetting at the edge of the
image tube field. The slit of the spectrograph
is replaced by a pair of circular apertures oriented
in the east-west direction so that the star and the
sky can be observed simultaneously.
SIT
The majority of the southern hemisphere WC stars
were observed by [Massey] at Cerro Tololo
Inter-American Observatory between November
1981 and February 1985. The SIT-Vidicon detector
was used on the Cassegrain spectrograph of the
1.5-m telescope. The SIT-Vidicon system has a
poor dynamic range, and since WC stars have very
strong emission lines, two exposures were in
general necessary: one to get good signal to
noise on the continuum and weak lines, with the
strongest lines usually saturated, and one to
get the strong lines unsaturated. The
unsaturated lines were inserted in the final re-
duction.
The user is referred to the original paper for more
detailed discussion of the observations.
[bytes 34-36, format A3]
No. of data points The number of valid entries to be found in the
data records for this observation. The total
number of data records can be calculated with the
FORTRAN statement:
NUMREC = ( ( NUMPTS- 1 ) / 5 ) + 1
The number of data points varies from 477 to 2961.
The number of data records varies from 96 to 253.
[bytes 37-42, format I6]
Comment If separate blue and red observations have been
made, this is noted in the comments. All other
comments should be self-explanatory.
[bytes 44-113, format A70]
2.3 DATA RECORDS
Several records containing the spectrophotometric data follow each
header record. The number of data records for each star depends on the
number of data points described above.
Fields for data points 2 through 5 in the last record in each group may
be blank, depending on the total number of data points.
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Bytes FORTRAN Format Data Name
1- 2 2X Blank
3- 8 F6.1 Wavelength 1
9- 21 E13.5 Flux 1
22- 28 F7.3 Magnitude 1
29- 30 2X Blank
31- 36 F6.1 Wavelength 2
37- 49 E13.5 Flux 2
50- 56 F7.3 Magnitude 2
57- 58 2X Blank
59- 64 F6.1 Wavelength 3
65- 77 E13.5 Flux 3
78- 84 F7.3 Magnitude 3
85- 86 2X Blank
87- 92 F6.1 Wavelength 4
93-105 E13.5 Flux 4
106-112 F7.3 Magnitude 4
113-114 2X Blank
115-120 F6.1 Wavelength 5
121-133 E13.5 Flux 5
134-140 F7.3 Magnitude 5
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Table 3. Data Record Format
Wavelength Wavelength of the observed data point in Angstroms.
Wavelength scale calibration for the IRS observations
was determined by exposing a He-Ne-Ar comparison source
every night. Wavelength scale calibration for the
SlT-Vidicon detector was determined by taking exposures
of a He-Ar and a Hg lamp. [bytes 3-8, 31-36, 59-64,
87-92, and 115-120 all format F6.1]
Flux In units of erg/s/cm2/A (mW/m2/A). Several
spectrophotometric standard stars were observed each
night to determine the spectrophotometric calibrations.
The user is referred to the original paper for
detailed discussion of the data reduction. [bytes 9-21,
37-49, 65-77, 93-105, and 121-133, all format E13.5]
Magnitude The fluxes were converted to magnitude units
using the calibration of Vega by Hayes and Latham
(1975), that is, m_v = -2.5log(f_nu)-48.594
By plotting the data in magnitudes instead of
flux units the relative strengths of the
lines can be readily compared from the plots, and
approximate colors at any given wavelength can be
read directly.
[Torres and Masseyl have chosen not to normalize the
[data], nor give any equivalent widths, line widths, or
intensities above the continuum in order to avoid any
errors that can be introduced by picking the continuum
level. All these quantities can be found in Torres (1985).
[bytes 22-28, 50-56, 78-84, 106-112, and 134-140,
all format F7.3]
3.0 HISTORY
3.1 REMARKS AND MODIFICATIONS
An "Atlas of Optical Spectrophotometry of Wolf-Rayet Carbon and Oxygen
Stars" (WRCOS) was received by the Astronomical Data Center (ADC), NASA
Goddard Space Flight Center, from A. V. Torres in April 1987. The
original data came in the form of 87 separate files: one file
containing Table I from Torres and Massey (1987) and 86 files each
containing the observed data for one star. These files were resident on
the Interactive Astronomical Data Analysis Facility (IADAF) VAX 11/750.
A Forth program was run to concatenate all the data files, while
merging in the records from Table I and copying the results to tape.
This tape file was copied to disk on the NASA Space and Earth Sciences
Computing Center (NSESCC) IBM 3081. FORTRAN programs were run to
reorganize this file into the format described in the previous sections.
A final FORTRAN program was run to check the validity of each field
according to its data type and value.
3.2 REFERENCE TO THE DOCUMENTATION
Azzopardi, M. and Breysacher, J. 1979, A. & A., 75, 120.
Breysacher, J. 1981, A. & A. Suppl., 43, 203.
Hayes, D. S. and Latham, D. W. 1975, Ap. J., 197, 593.
Torres, A. V. 1985, Ph. D. Thesis, Univ. of Colorado.
Torres, A. V., Conti, P. S., and Massey, P. 1986, Ap. J., 300, 379.
Torres, A. V. and Massey, P. 1987, An Atlas of Optical Spectrophotometry
of Wolf-Rayet Carbon and Oxygen Stars, Ap. J. Supp., 65, 459.
van der Hucht, K. A., Conti, P. S., Lundstrom, I., and Stenholm, B. 1981,
Space Sci. Rev., 28, 227.
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