[daip] Number of digits for positions.

[R. Craig Walker]

I keep running into problems with inadequate number of digits in displays
of positions from AIPS.  It's been getting better, but progress is still
needed.  I have a resolution of 200 microarcseconds and a cell size of 35
microarcseconds.  This message was triggered by MFPRT which shows the
positions to 10 microarcseconds.  While that is better than my positional
accuracy, it is only just barely better and will introduce an undesired
granularity.  Another case is IMHEAD, which gives positions to 1 mas in
Dec and 15 mas in RA.  LISTR gives positions to a milliarcsecond.  PRTAB
on the SU table gives RA and Dec to 1.E-5 degrees, about 36 mas.  JMFIT
actually has plenty of digits in output from the program.  But I'm not
sure how to recover that if it wasn't saved at run time.  Some programs
like CNTR do show plenty of digits.

One suggestion for images, anyway, would be to try to display enough
digits to extract positions to at least 1/1000 of a cell size.

This is a low priority, but long festering, issue.

Cheers,

Craig







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    R. Craig Walker            Array Operations Center
    cwalker at nrao.edu           National Radio Astronomy Observatory
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