relative fluxes

[Alberto Micol]

Hi Randy,

I meant the format like for:

http://www.ucm.es/info/Astrof/fgkmsl/hd185395_hb_5.fit

(thanks Petr! very good collection of examples!)

where the primary header unit shows something like:

NAXIS = 1
NAXIS1 = 1024
CRPIX1 = 1
CRVAL1 = 4500 /[angstrom]
CDELT1 = 2.5 /[angstrom]

and the spectrum is stored in a 1d array of linear wavelengths.


Though is clear that additional VO metadata would be needed, that could
done at the level of the VOTABLE, leaving the FITS unchanged.

Thanks,
Alberto


> On 29 Jun 2009, at 16:17, Randy Thompson wrote:
>
> Alberto Micol wrote:
> I can report that ESO stores spectra in 1D image format.
>
> It would indeed be nice to know which other data providers use the 1D 
> FITS IMAGE format
> for their 1D spectra in their archives...
>
> Hi Alberto,
>   I've seen the term 1-D FITS used a lot lately, but have never seen a 
> definition. Does it refer to
> a file with an array of fluxes stored as a primary array and (linear) 
> wavelengths defined with keywords
> (e.g., WUPPE)? Does it include data where an array of wavelengths are 
> stored in one file and an
> array of fluxes in another (e.g., FOS, GHRS)?  Does it includes files 
> where arrays of flux, wavelength,
> error estimates, and sigmas are all merged together into one 
> non-homogeneous primary array  (e.g., HUT)?
> I think you may be grouping a family of file formats under the title 
> "1-D FITS".
>   We have archived files within MAST in all these formats and more, 
> and is the reason we are
> creating VO-compatible versions. The conversion of the data itself was 
> not difficult using existing IDL
> routines. The difficulty is usually in calculating the metadata 
> necessary to allow data from one mission
> to be compared with that of another;  something that needs to be 
> provided with any file format.
>
> Randy

-- 
Alberto Micol
Telephone: +49 89 32006 261
Fax:       +49 89 32006 898
Virtual Observatory Standards Group Lead
Virtual Observatory Project Office
Data Management and Operations Division
European Southern Observatory