[fitsbits] 64-bit integer comments

[Mike Nolan]

> It certainly seems easy enough to add the support, but "because we can"
> does not really feel like a good enough reason by itself. The only 
> possibility of use that I have seen is William's mention of "only
> moderately contrived examples", which does not quite match my standard.
> If it's available somebody will use it for no good reason, and then
> every generic reader around will be pushed towards supporting it
> against their will.
> 
> Unless somebody comes up with a project that will fly within 5 years
> and that needs 64 bits of dynamics in images, what's wrong with just
> waiting until some actual need occurs?


I'd like to present an alternate point of view that may or may not be
of interest. I have convinced my observatory that some form of FITS
should be well supported. Is it in fact the native format for the
current spectrometer. My reason is data archiving: We have tons of old
data in formats that can no longer be read. This worked because FITS
already supported a format that would work: binary tables with data in
the heap. Unfortunately, not many astronomical packages can usefully
read binary tables (specifically arrays), but everybody does like the
fact that fv immediately gives them something they can look at. And I
like to tell them that fv will let them look at it 20 years from now
too.

I guess that my point is that if you wait for the need, it will come
and go before you can use it. If the solution is clear and much of the
software implements it anyway, it's time to do it; particularly when
there are a few decisions to make (e.g. signed or not) that can be
worked around either way, but not if half choose one and half the
other.