III/44 Atlas of Stellar Spectra (Johnson 1977-1978)
An Atlas of Stellar Spectra
Johnson H.L.
<Rev. Mex. Astron. Astrof. 2, 71 (1977)>
=1977RMxAA...2...71J 1977RMxAA...2...71J
<Rev. Mex. Astron. Astrof. 4, 3 (1978)>
=1978RMxAA...4....3J 1978RMxAA...4....3J
ADC_Keywords: Spectrophotometry
Description:
There are exactly 8192 spectral elements (points) in each spectrum,
regularly spaced in terms of frequency. The first point corresponds to
spectral frequency 0, while point number 8193 (not included) corresponds
to the laser frequency. The 632.8nm laser frequency was doubled,
producing an effective laser wavelength of about 316.4nm.
Tentatively, it may be assumed that the exact laser wavelength is
316.43nm.
The spectra have been normalized so that the bluest stars are
approximately level from 480 to 1000nm. The spectra are linear
in intensity with zero intensity at tabulated zero. It was not
possible to make satisfactory atmospheric extinction corrections
throughout all of the atmospheric bands; at places where corrections
could not be made, the spectra were set (exactly) to zero.
Some of these spectra have been published already (H.L. Johnson,
Rev. Mex. Astron. Astrof. 2, 71, 1977); the remainder will be
published soon (Rev. Mex. Astron. Astrofis., 4, 3). These published
spectral plots contain in graphical form the information needed to
evaluate the signal-to-noise ratios of the spectra on this tape.
(From Harold L. Johnson, Dec. 13, 1977)
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
stars.dat 60 54 List of the stars
atlas.dat 74 55296 The Atlas (54 spectra)
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Byte-by-byte Description of file: stars.dat
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Bytes Format Units Label Explanations
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1- 2 I2 h RAh ? Right Ascension J2000 (hours) (1)
4- 5 I2 min RAm ? Right Ascension J2000 (minutes) (1)
7- 10 F4.1 s RAs ? Right Ascension J2000 (seconds) (1)
12 A1 --- DE- ? Declination J2000 (sign) (1)
13- 14 I2 deg DEd ? Declination J2000 (degrees) (1)
16- 17 I2 arcmin DEm ? Declination J2000 (minutes) (1)
19- 20 I2 arcsec DEs ? Declination J2000 (seconds) (1)
24- 33 A10 --- Name Name of the star
39- 42 I4 yr Obs.Y ? Observation date, year (2)
44- 46 A3 "month" Obs.M ? Observation date, month (2)
48- 49 I2 d Obs.D ? Observation date, day (2)
51- 52 I2 h Obs.h ? Observation date, hour (2)
53 A1 --- --- [:]
54- 55 I2 min Obs.m ? Observation date, minute (2)
58- 60 I3 --- Nobs Number of observations.
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Note (1): the star position has been added at CDS (no position for Uranus)
Note (2): The exact date is not specified when the spectrum is a mean
of several observations.
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Byte-by-byte Description of file: atlas.dat
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Bytes Format Units Label Explanations
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1- 10 A10 --- Name Name of the star
11- 74 8I8 --- I 8 spectral fluxes per frquency; there are
1024 lines per star. There are
therefore 8192 points per spectrum (1)
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Note (1): with the values assumed in the Description, the values of
the wavenumbers, expressed in cm-1, are given by
SIGMA(I) = 3.8577 * (I-1)
and wavelength, in Angstroems, by
WAVELEN(I) = 1.E8/(3.8577 * (I-1))
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(End) Francois Ochsenbein [CDS] 28-Oct-1993, revised 02-Mar-1998