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III/116             Spectrophotometric Standards      (Massey+ 1988)

Spectrophotometric Standards Massey P., Strobel K., Barnes J.V., Anderson E. <Astrophys. J. 328, 315 (1988)> =1988ApJ...328..315M
ADC_Keywords: Spectrophotometry ; Stars, standard Abstract: Observers at the National Optical Astronomy Observatories have provided spectrophotometry for 25 stars in the visual magnitude range 7.5 to 16.6. This document describes the machine-readable version of their results as received from P. Massey. The magnitudes are on the Hayes-Latham system and cover the wavelength range from 3200 to 8100 angstroms at approximately two angstrom intervals. Description: The stellar magnitude system is based on the brightness of Vega at each wavelength. Vega, itself, has been compared accurately with laboratory standards. Unfortunately, Vega is much too bright to be observed under the same conditions with most stars of interest. Hence, various investigators have compared carefully with Vega and a few other primary standards somewhat fainter stars to be used as secondary standards. In addition, several much fainter stars have been used as tertiary standards with lower accuracy. With the common use of linear detectors and large telescopes, it has become important to provide spectrophotometric standards for a range of magnitudes including quite faint stars. The planning for the Hubble Space Telescope increased the necessity for fainter standards. Moreover, both the IUE and the HST require that the standards be established at the shortest wavelength reliably accessible from the ground so that ultraviolet spectrophotometry can be tied to visual spectrophotometry accurately. Investigators at Kitt Peak National Observatory have pursued a lengthy program to provide both more accurate spectrophotometry of faint stars and a dense distribution of the wavelengths at which the fluxes are measured. The close spacing of points is essential to place the fairly short stretches of a high resolution spectrum available with a solid state detector on a standard system. The present compilation provides improved data for nine stars previously observed by Stone (1977) or Oke (1974) and spectro- photometry of 16 new standards, eight of which are fainter than 14.0 mag. To provide red standards and still avoid stars with numerous spectral lines, a highly reddened O5 star and two substantially reddened (but bright) O5 stars are included. The observations were all referenced to either BD+28 4211 or Feige 34. For four stars in common, comparison with the data from Stone indicates that the calibration of the standard stars is good to about 0.03 mag. The internal accuracy of the data for the individual stars is substantially higher. The measurements are on the Hayes-Latham system. Table 1 describes the stars. It is identical to Table 1 in the source reference except that V has been omitted. The number of observations per star ranges from 3 to 29, but not all observations were made under photometric conditions. Only one observation of Feige 110 was made under photometric conditions. For PG 0205+134, PG 0310+149, PG 0939+262, PG 1121+145, and PG 1545+035, only two measurements were made under photometric conditions. The magnitudes for HZ44 show a large scatter within the 29 measurements. Fig. 1, also from the source reference, provides finding fields for all stars except for the two brightest. File Summary:
FileName Lrecl Records Explanations
ReadMe 80 . This file table1.dat 88 25 List of stars with spectrophotometry sp01.dat 16 2556 Spectrum of PG 0205+134 sp02.dat 16 2718 Spectrum of PG 0216+032 sp03.dat 16 2556 Spectrum of PG 0310+149 sp04.dat 16 2729 Spectrum of HZ 14 sp05.dat 16 2730 Spectrum of G 191B2B sp06.dat 16 2525 Spectrum of Hiltner 600 sp07.dat 16 2526 Spectrum of PG 0823+546 sp08.dat 16 3054 Spectrum of PG 0846+249 sp09.dat 16 2515 Spectrum of PG 0934+554 sp10.dat 16 3053 Spectrum of PG 0939+262 sp11.dat 16 3461 Spectrum of Feige 34 sp12.dat 16 2931 Spectrum of PG 1121+145 sp13.dat 16 2516 Spectrum of GD 140 sp14.dat 16 2533 Spectrum of EG 81 sp15.dat 16 2533 Spectrum of Feige 66 sp16.dat 16 2533 Spectrum of Feige 67 sp17.dat 16 3345 Spectrum of HZ 44 sp18.dat 16 1863 Spectrum of PG 1545+035 sp19.dat 16 2433 Spectrum of PG 1708+602 sp20.dat 16 2433 Spectrum of HD 192281 sp21.dat 16 2434 Spectrum of Cyg OB2 No.9 sp22.dat 16 2434 Spectrum of Wolf 1346 sp23.dat 16 3209 Spectrum of BD +28 4211 sp24.dat 16 2433 Spectrum of HD 217086 sp25.dat 16 2419 Spectrum of Feige 110 spectra 105 4468 *All spectra in a single file
Note on spectra: This file contains all 25 spectra as a single file. The information for each star begins with a header record. This record contains, in order, the star name, the number of data points, the wavelength of the first data pixel (in angstroms), and the wavelength per pixel. These header records are the only ones for which the first byte is not blank. The star name starts in byte 1 in the header; the remaining information follows in order with one or more blanks between each type of information but the format is otherwise not uniform. The remaining records before the next header record contain the data. Each magnitude has its decimal point in every seventh byte, starting with byte 4.
Byte-by-byte Description of file: table1.dat
Bytes Format Units Label Explanations
1- 8 A8 --- File Name of the file which contains the spectrophotometry 11- 22 A12 --- Star Name of the star 24- 25 I2 h RAh Right Ascension 1950 (hours) 27- 28 I2 min RAm Right Ascension 1950 (minutes) 30- 33 F4.1 s RAs Right Ascension 1950 (seconds) 35 A1 --- DE- Declination 1950 (sign) 36- 37 I2 deg DEd Declination 1950 (degrees) 39- 40 I2 arcmin DEm Declination 1950 (minutes) 42- 43 I2 arcsec DEs Declination 1950 (seconds) 46- 49 A4 --- SpType Spectral type 52- 56 F5.2 mag m5666 Magnitude (1) 58- 62 F5.2 mag B-V ? colour 65- 88 A24 --- Notes Notes concerning the star
Note (1): All magnitudes are m_5556 except for PG 0934+554 for which V is given. For PG 0205+134, PG 0216+032, PG 0310+149, PG 0939+262, and PG 1708+602, the g-v indices of Green, Schmidt, and Liebert have been substituted for B-V.
Byte-by-byte Description of file: sp*.dat
Bytes Format Units Label Explanations
1- 9 F9.4 0.1nm Lambda Wavelength (Angstroems) 11- 16 F6.3 mag m(Lambda) ?=0.00 Magnitude on the Hayes-Latham system
Acknowledgments: We thank Dr. Massey for forwarding to us the Spectrophotometric Data in easily machine-readable form and for the accompanying reprint. References: Green, R.F., Schmidt, M., and Liebert, J. 1986, ApJS, 61, 305 Hayes, D.S. and Latham, D. W. 1975, ApJ, 197, 593 Oke, J.B. 1974, ApJS, 27, 21 Stone, R.P.S. 1977, ApJ, 193, 135 Whiteoak, J.B. 1966, ApJ, 144, 305 Historical Notes: * September 1991 at ADC: The Spectrophotometric Standards catalog was received from Dr. Massey in August 1987 in 25 machine-readable files, one for each star. These files have been concatenated into a single file. The documentation was written by Nancy G. Roman, Doc. No. NSSDC/WDC-A-R&S 91-09 Files on the "Selected Astronomical Catalogs" Vol. 1 CD-ROM, directory /spectro/spstd * 11-Sep-1995: documentation standardized; individual files have been recreated to allow standard conversions into FITS of each spectrum.
(End) Francois Ochsenbein [CDS] 11-Sep-1995
The document above follows the rules of the Standard Description for Astronomical Catalogues.From this documentation it is possible to generate f77 program to load files into arrays or line by line

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