Dimensionless units

[Ivo Busko]

Igor Chilingarian wrote:
<snip>
> During last AVO demo such synthetic spectra were shown on the same plot with
> spectrophotometrical data, and the question about it was raised.
> Actually, to compare directly synthetic spectra (for galaxies) with observed
> data, one should assume some mass and distance for this "theoretical
> object".

If you're talking about Specview, to coplot both sets of data
together, Specview requires that they share the same units. To 
that end, Specview assumes that theoretical fluxes are "unitless", 
and thus allows its input values to be modified by a user-chosen, 
arbitrary multiplicative factor to convert them to the observational
flux units. Since one is interested in just matching the shapes (or 
minimize chi-sq if one wants to go quantitative), there is no need 
to know distances or sizes or anything like that. 

-Ivo

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