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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 <Rev. Mex. Astron. Astrof. 4, 3 (1978)> =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:
FileName Lrecl Records Explanations
ReadMe 80 . This file stars.dat 60 54 List of the stars atlas.dat 74 55296 The Atlas (54 spectra)
Byte-by-byte Description of file: stars.dat
Bytes Format Units Label Explanations
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.
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.
Byte-by-byte Description of file: atlas.dat
Bytes Format Units Label Explanations
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)
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))

(End) Francois Ochsenbein [CDS] 28-Oct-1993, revised 02-Mar-1998
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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