[fitsbits] [mhvk at astro.utoronto.ca: Question about FITS format for logarithmic units]

[Peter Weilbacher]

Hi Marten,

On Wed, 11 Dec 2013, Marten van Kerkwijk wrote:

> Anyway, while the above discussion is very interesting,

I had understood the discussion so far such that you shouldn't do what
you are planning to do in the way that you want to do it. I wouldn't
brush the points that were raised aside as easily.

But since are are determined to do it anyway, I can at least try to
address this one:

> (1) How would I indicate a dimensionless but logarithmic quantity such
>     as dex? If I understood the standard correctly, log(surface gravity)
>     might have the unit "log(cm/s2)", but how about a dimensionless one
>     (like metallicity).  Would it be "log()", or, by analogy with
>     magnitude, just "log"?

If something has no unit that the unit could be viewer to be unity.
Hence I would say use log(1). Leaving the argument empty would otherwise
probably break parsers.

   Peter.
-- 
Dr. Peter Weilbacher                http://www.aip.de/People/PWeilbacher
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