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III/116 Spectrophotometric Standards (Massey+ 1988)
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Spectrophotometric Standards
Massey P., Strobel K., Barnes J.V., Anderson E.
<Astrophys. J. 328, 315 (1988)>
=1988ApJ...328..315M
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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:
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FileName Lrecl Records Explanations
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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.dat 105 4468 *All spectra in a single file
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Note on spectra.dat:
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
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Bytes Format Units Label Explanations
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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
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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
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Bytes Format Units Label Explanations
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1- 9 F9.4 0.1nm Lambda Wavelength (Angatroems)
11- 16 F6.3 mag m(Lambda) Magnitude on the Hayes-Latham system
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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.
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(End) Francois Ochsenbein [CDS] 11-Sep-1995