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 ================================================================================ 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. -------------------------------------------------------------------------------- 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 -------------------------------------------------------------------------------- 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. -------------------------------------------------------------------------------- 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 -------------------------------------------------------------------------------- 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. -------------------------------------------------------------------------------- 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 -------------------------------------------------------------------------------- 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. ================================================================================