[fitsbits] FITS changes

[Rob Seaman]

On Aug 6, 2007, at 6:24 AM, Kevin Thomas wrote:

> We need a "Don't Make Me Think" policy with the FITS format.

More standards might benefit from users and programmers having to think.

> As a programmer, even after reading the documentation on the FITS  
> format, I still struggle with the header portion of the file. How  
> does one know how many 2880 byte chunks preceed the image data????

if (keyword == END) then data follows (but not necessarily image data)

In general, think in terms of 80 character Hollerith card images.   
Historical perspective is always of benefit - e.g., the global  
comprehension of logarithms has plummeted since the demise of the  
slide rule.

> Like the ARF files we use currently at my work (defense) the format  
> is overly complex and poorly thought out.

Rather, its complexity is proportionate to the task - and much  
thought and consensus-building (and evolutionary pressure) have gone  
into the design choices.

I don't know what ARF is, since google and other web resources are of  
little help:

	http://www.arf.net (top hit) or
	http://en.wikipedia.org/wiki/ARF (disambiguation, e.g., "Armenian  
Revolutionary Federation")

On the other hand, google FITS:

	http://fits.gsfc.nasa.gov (top hit) and
	http://en.wikipedia.org/wiki/FITS

from which we find, for instance, that "FITS is the most commonly  
used digital file format in astronomy."  Rare indeed must be  
standards with the overwhelming market penetration of FITS.  One also  
doubts that the ARF specification is published in the refereed  
literature:

	http://adsabs.harvard.edu/abs/1981A%26AS...44..363W

On Aug 6, 2007, at 9:44 PM, Steve Allen wrote:

> There weren't any other questions in the original post, so it's  
> hard to provide any other answers other than to note that FITS was  
> designed when 32 k was a lot of directly addressable memory, and  
> everything else was found by running the tape back and forth until  
> the item in question was either found or not.

More standards could benefit from a similar dose of self-restraint in  
minimizing resource requirements.  One might have cause, for  
instance, to be skeptical that many emerging XML-based standards will  
still be in wide use a quarter century hence.  (Although one trusts  
VOEvent will be one of the shining exceptions :-)

Personally, I'm quite confident that FITS will still be with us in 2032.

Rob Seaman
NOAO
------

A classic is classic not because it conforms to certain structural  
rules, or FITS certain definitions (of which its author had quite  
probably never heard). It is classic because of a certain eternal and  
irrepressible freshness.  - Edith Wharton

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