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11.2 Standard Star Spectra

  The IUEDAC has on line a set of representative low dispersion standard star spectra of spectral types O-M and luminosity classes V-Ia from the IUE Standard Star Atlas (1983, NASA IUE Newsletter, 22). The spectra are stored as both IUESIPS MELO files and NEWSIPS MXLO files, and may be extracted and reduced using the same software as used for your program spectra. When running IUESPEC or READMX, you must include the disk and account name (or an equivalent logical assignment) for these spectra. For example, to run IUESPEC on SWP 11224 from the standard star atlas, type:

IUESPEC,!iuer.stds+'SWP11224LLG',H,W,F,E

where ``!iuer.stds'' will supply the path information needed to find the standard star spectra.

The standard stars are stored in a directory on IUE, rather than in a formal database. However, there is a Log of information pertinent to the data which is in database format; there is a menu procedure similar to SEARCH to look at it:

STDSTARS,RESET,list,fmtfile=fmtfile 

RESET Search parameters will be returned, and can be re-used, via RESET. You may enter 0 if you are not interested in saving these.
list List of entry numbers for the standard star log database. It may be used with the lower-level database routines. If you are interested in using these routines, contact a staff member or consult the file dbexpert.txt in the !iuer.inf directory.
fmtfile You may create (within STDSTARS) a file telling the program how to format the output. This file can be saved for later use.

The IUESIPS standard star data files have been set up so that they already contain the exposure time, THDA value, etc. The user may run IUESPEC on them without knowing that information. To create a vector of file names of standard stars:

STDSFILE,FILE,type,cam,im,ap,obj,hd,exp,srch=srch,/newsips 

FILE Output list of file names matching the criteria you entered.
type Spectral type to search for, e.g., "b3". If it is a variable, it will be reset to match those items actually found and will have the same dimensions as FILE. If you do not wish to constrain the search by spectral type, enter a null string.
cam Camera(s) to look for. The allowed cameras are LWP, LWR, and SWP. Either those names or their numbers (1, 2, and 3, respectively) may be entered. If it is a variable, it will be reset to match the cameras for those entries actually found and will have the same dimensions as FILE. If you do not wish to constrain the search by camera, enter 0.
im Image sequence number(s) to search for. If a variable, it will be reset to match those entries actually found and will have the same dimensions as FILE. If you do not wish to restrain the search by image sequence number, enter 0.
ap Aperture to look for (L or S). If it is a variable, it will be reset to match the apertures of the items actually found and will have the same dimensions as FILE. If you do not wish to constrain the search by aperture, enter a null string.
obj Object names of items found. Strictly an output parameter, it will have the same dimensions as FILE.
hd HD numbers of items found. Strictly an output parameter, it will have the same dimensions as FILE.
exp Exposure times of items found. Strictly an output parameter, it will have the same dimensions as FILE.
srch Normally, STDSFILE will use the values of the type, cam, im, and ap parameters to construct a search string for use by the lower level database procedure IDBFIND. If you know how to use the database routines, you can enter a search string via SRCH. If you do, type, cam, im, and ap will be strictly output parameters with the same dimensions as FILE.
newsips If specified, newsips (rather than IUESIPS) files will be searched.

An alternative to using IUESPEC to read IUESIPS files is RDSTDS. RDSTDS will read the data, apply sensitivity corrections as appropriate (see Section 5.4), and optionally, patch, plot, and/or convert the results to an ASCII file:

RDSTDS,FNAME,h,w,f,q,/patch,/plot,afile=afile, $
type=type,aper=aper
 

FNAME File name or names (e.g., from STDSFILE) to read.
h,w,f,q The usual vectors from IUESPEC. If more than one file was read, these will pertain to the LAST file read.
patch If set, the data will have points with negative quality flags patched before the sensitivity correction is applied.
plot If set, the data will be plotted after the sensitivity correction is applied.
afile If set, wavelengths and fluxes will be written to an ASCII file readable with ASC_READ. Default file name is imaget.TXT; afile may be set to a different extension, or to a complete file name.
type If set, STDSFILE will be called to generate a list of standard star files for the desired spectral type. FNAME will be reset to this list.
aper Specifies the type of aperture ('L' for large, or 'S' for small) to be extracted. Used when type keyword is specified, or when newsips files are specified with fname. Default = 'L'.

Note that NEWSIPS files can also be converted to ASCII files using the program FTOA.

You may generate your own list of file names; they do not have to be standard star files. The sensitivity degradation procedures RBSENSCOR or LWPCORFLUX will be called. Do not elect to correct for the degradation if IUESPEC asks!


next up previous contents
Next: 12 AUXILARY CATALOGS Up: 11 COMPARISON SPECTRA Previous: 11.1.2 ``Old'' Kurucz Models

2/9/1998