Tony Willis

Have a look at the demo programs CPUplot.py and DataDemo.py in the subdirectory qwt/tests. They could provably be adapted to do what you want.

Anybody figure this one out? I think the problem is that astropy precessed positions seem to be incorrect. I compared the output of astropy, skyfield and CASA measures (see the...

You raise some of the issues I've thought about myself. Why does AZ/El agree pretty well with all three systems, while astrypy apparent RA/DEC is so out of wack? I...

It looks like J2000 and ICRS only differ by a few milli-arcseconds in positions at most whereas my astropy apparent positions are off by many arcsec so I don't think...

@bmerry - thanks for this. :-) I'd never heard of CIRS before. You are correct re astropy EFRA calculations - that's why astropy returns a correct Az/El with ICRS coordinates....

@bmerry As I recall you are correct in that casacore (still) uses AZEL as the default specification for the derivation of Azel from a latitude and longitude. I have no...

This issue has also cropped up in https://github.com/ska-sa/meqtrees/issues/877 where there is a plot of the difference between geodetic and geocentric elevation as a function of observer latitude.