IUE Ultraviolet Spectral Atlas of Standard Stars

Computer Sciences Corporation

Catalogues

This page gives some basic information associated with the 476 standard stars, including the HD number, star name, spectral type and luminous class, reference key number for spectral_type and the luminous_class, RA (Right Ascension) and Dec (Delination), V magnitue, remarks, B-V, and E(B-V).

For each star, an UV spectra page can be accessed through the HD number or the star name in the atlas page. The spectra page provides the informaton of the IUE observations and the outputs of the IUE data processing. The outputs include spectral plots and the w_f tables for each observation. A weighted combined spectrum is made for each camera, if two or more observations are available for the object or the mxlo is a double (large and small) aperture image.

Columns Description

Cloumn	Units	Explanations
HD		HD number
Name		name of the star
Sp_Type		spectral type
Ref		key to data source for spectral type
RA	hh:mm:ss	right ascension (1950.0)
DEC	dd:mm:ss	declination (1950.0)
V	mag	V magnitude
Remarks		remarks on duplicity / variability
B-V	mag	B-V colour index
E(B-V)	mag	color excess on B-V

Reference Sources of Spectral Type

The spectral type in this page is assembled from various sources. The column Ref indicates the key number to the data source for the spectral type. Those reference sources are listed in Table 2.

Key Number	Peference Source
1	Morgan and Keenan 1973
2	Johnson and Morgan 1953
3	Walborn 1982
4	Walborn 1973
5	Walborn 1972
6	Lesh 1968
7	Lesh 1972
8	Garrison, Hiltner and Schild 1977
9	Morgan, Code and Whitford 1955
10	Cowley, Clwley, Jaschek and Jaschek 1969
11	Keenan and Pitts 1980
12	Keenan and Pitts 1981
13	Jaschek 1980
14	Buscombe 1984
15	Hoffleit 1982
16	O'Connell 1973

Star Coordiates: RA & DEC

The RA and DEC are retrieved from the SAO (Smithsonian Astrophysical Observatory) Star Catalog

Photometric Data

The source of the photometric data are taken from the Catalogue of Mean UBV Data on Stars, an on-line catalog from J.-C. Mermilliod and M. Mermilliod, 1998. In the column Remarks, following the notation of the UBV catalog, an "A" indicates that the star has a close neighbor and that the V magnitude is only for the brighter component. On the other hand, an "AB" indicates that the V magnitude is the combined brightness of the both components. The column E(B-V) is observed B-V (in column 9) minus the intrinsic B-V from FitzGerald (1970). The E(B-V) values assume that the intrinsic B-V's for higher luminosity O stars are the same as main sequence stars of the same spectral type. The computations of E(B-V) for spectral types and luminosity classes, which have no intrinsic B-V in FitzGerald, used interpolated values of B-V.

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UV Spectra

This section presents the Graphics and Flux Tables of the UV spectra of the IUE Standard Stars, the outputs of the data processing from the IUE NEWSIPS MXLO data. The star information, appeared on the page top, is transferred from the Atlas Page.

For each observation, the output of the data processing includes a pair of spectral graphics (a gif file and a ps file) and a w_f (wavelength_flux) text table. Users can access these files by pointing to any of the (gif), (ps) or (w_f) files.

Description of the MXLO Image Log

• Image : camera(LWR/LWP/SWP) plus image sequence number
  * (gif) - graphics of mxlo spectrum in GIF format
  * (ps) - graphics of mxlo spectrum in PostScript format
  * (ps) - graphics style (color, line style, and marker)

  MXLO Data	Large Aperture Spectra	Small Aperture Spectra
  Spectra	Black Solid Line	Violet Dashed Line
  Bad Data Points	Red Cross	Blue Asterisk

• (w_f) - mxlo wavelength_flux table in ASCII text format
  * w : wavelength
  * fL : flux of large aperture image
  * qL : DQF for large aperture image
  * fS : flux of small aperture image

• Ap : aperture (Large/Small)

• N : number/T
  * number - the number of exposure along the major axis of the large aperture
  * T - trail mode observation

• Exp : exposure time in seconds

• E/C/B : DN (Data Number) level of E/C/B, comment by Resident Astronomer of the IUE observatory
  * E - maximum Emission
  * C - maximum Continuum
  * B - mean Background

Combined Image

• Single Aperture Exprosure & Double Aperture Exprosure
  * Single Aperture Exprosure : A weighted combined spectrum is given for each camera, if two or more Large aperture images are available. The weighting factor is the total exposure time.
  * Double Aperture Exprosure :

• Description of the Combined Image Log
  * (gif) - combined spectrum in GIF format
  * (ps) - combined spectrum in PostScript format
  * (w_f) - combined wavelength_flux table in ASCII text format

  Table Column	Single Aperture Spectra	Double Aperture Spectra
  wavelength	w	w
  flux (of combined spectra)	fcomb	fLSc
  DQF (of combined spectra)	qcomb	qLSc

Notes

• The ps graphics have the same wavelength range and scale as those in The IUE Ultraviolet Spectral Atlases, published in the NASA NEWLETTER No.22, 1983 and No.43, 1993. Users may browse and/or print the ps file from Netscape Navigator directly.

• Users may use GSview as a PostScript files viewer under
  * OS/2
  * MS-Windows 3.1/Win32s
  * MS-Windows 95/98
  * MS-Windows NT for
  * IBM WebExplorer
  * NCSA Mosaic
  * Netscape Navigator
  * Internet Explorer

• For the double aperture spectra, a scaled image for small aperture image is overploted onto the large aperture spectrum. Users must keep in mind, the small-aperture fluxes are known in a relative sense but not in an absolute one, and the absolute fluxes for small-aperture data are significantly less reliable than those of large-aperture data.

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