[AstroPy] fits coordinate system keyword
Paul Kuin
npkuin at gmail.com
Mon Oct 5 17:47:11 EDT 2015
That is so. You're absolutely right! I'm so sorry! I did not catch that
one.
That is probably an error that sneeked into the FITS headers from Swift.
Perhaps its a Heasarc thing, but somehow I think its a bug.
Thank you all for helping with this.
Paul
On Mon, Oct 5, 2015 at 10:17 PM, Thomas Robitaille <
thomas.robitaille at gmail.com> wrote:
> I think there is a misunderstanding:
>
> RADECSYS is not valid
>
> RADESYS is valid
>
> (note the extra C). We are not debating that RADESYS is valid - it is -
> but the warning concerns the common mis-spelling of RADE*C*SYS. Does
> this make sense?
>
> Cheers,
> Tom
>
> Paul Kuin wrote:
> > In the WCS II standard paper ( M. R. Calabretta and E. W. Greisen:
> > Representations of celestial coordinates in FITS
> > http://www.aanda.org/articles/aa/pdf/2002/45/aah3860.pdf) on page 1079
> > the is a table defining some variables used. In particular 'a' is
> > alternate version code 'blank or [A-Z]. In table 2 on page 1082, the
> > definition is RADESYSa, meaning that valid versions are either RADESYS,
> > RADESYSA, RADESYSB, ... , RADESYSZ.
> >
> > So it always was defined as a valid. Similar, EQUINOXa/. I've seen that
> > mostly used as just EQUINOX. If the header has just one WCS block, or a
> > preferred one, that is useful to have.
> >
> > Let's see what Bill Pence says. Maybe there were some changes after all.
> >
> >
> >
> > On Mon, Oct 5, 2015 at 8:34 PM, Thomas Robitaille
> > <thomas.robitaille at gmail.com <mailto:thomas.robitaille at gmail.com>>
> wrote:
> >
> > Hi Paul,
> >
> > Just out of curiosity, was RADECSYS ever a keyword in the FITS
> standard,
> > as opposed to RADESYS? (which is the currently valid keyword). If
> so, in
> > what version of the standard?
> >
> > Cheers,
> > Tom
> >
> > Paul Kuin wrote:
> > > Actually, one of the basic tenets of FITS is to be completely
> backward
> > > compatible, so any keyword that was valid in the past is valid
> now. So
> > > that warning is also inaccurate. If it was standard, it still is,
> and
> > > ever will be.
> > >
> > >
> > >
> > > On Mon, Oct 5, 2015 at 5:25 PM, Erik Bray <embray at stsci.edu
> > <mailto:embray at stsci.edu>
> > > <mailto:embray at stsci.edu <mailto:embray at stsci.edu>>> wrote:
> > >
> > > On 10/05/2015 12:17 PM, Paul Kuin wrote:
> > >
> > >
> > >
> > > I am getting very annoyed of the warning that keeps
> popping up
> > >
> > > WARNING: FITSFixedWarning: RADECSYS= 'FK5' / default
> > > RADECSYS is non-standard, use RADESYSa. [astropy.wcs.wcs]
> > >
> > > I'm not sure when the FITS standard changed, but MOST
> legacy
> > > fits files (I use)
> > > will have the RADECSYS keyword. It works, and I do not see
> why
> > > someone felt the
> > > need to keep this warning being popped up all the time.
> > >
> > >
> > > Probably as a warning to remind authors of new files that they
> > > shouldn't be using that keyword. I don't know that it
> necessarily
> > > needs to be displayed every time reading in a WCS except maybe
> to
> > > head off cases of ambiguity. But I don't know this particular
> > issue
> > > well enough to be sure if the warning is appropriate in all
> > cases or
> > > not.
> > >
> > > I think that by default it should be off.
> > >
> > > Since you all probably think it should be there, I would
> > like to
> > > know how to
> > > turn it off ? any suggestion on how to do that?
> > >
> > >
> > > http://docs.astropy.org/en/stable/warnings.html
> > >
> > >
> > > Erik
> > >
> > > _______________________________________________
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> > <mailto:AstroPy at scipy.org <mailto:AstroPy at scipy.org>>
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> > >
> > >
> > >
> > >
> > > --
> > >
> > > * * * * * * * * http://www.mssl.ucl.ac.uk/~npmk/ * * * *
> > > Dr. N.P.M. Kuin (n.kuin at ucl.ac.uk <mailto:n.kuin at ucl.ac.uk>
> > <mailto:n.kuin at ucl.ac.uk <mailto:n.kuin at ucl.ac.uk>>)
> > > phone +44-(0)1483 (prefix) -204927 (work)
> > > mobile +44(0)7806985366 <tel:%2B44%280%297806985366> skype ID:
> npkuin
> > > Mullard Space Science Laboratory – University College London –
> > > Holmbury St Mary – Dorking – Surrey RH5 6NT– U.K.
> > >
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> >
> >
> >
> >
> > --
> >
> > * * * * * * * * http://www.mssl.ucl.ac.uk/~npmk/ * * * *
> > Dr. N.P.M. Kuin (n.kuin at ucl.ac.uk <mailto:n.kuin at ucl.ac.uk>)
> > phone +44-(0)1483 (prefix) -204927 (work)
> > mobile +44(0)7806985366 skype ID: npkuin
> > Mullard Space Science Laboratory – University College London –
> > Holmbury St Mary – Dorking – Surrey RH5 6NT– U.K.
> >
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--
* * * * * * * * http://www.mssl.ucl.ac.uk/~npmk/ * * * *
Dr. N.P.M. Kuin (n.kuin at ucl.ac.uk)
phone +44-(0)1483 (prefix) -204927 (work)
mobile +44(0)7806985366 skype ID: npkuin
Mullard Space Science Laboratory – University College London –
Holmbury St Mary – Dorking – Surrey RH5 6NT– U.K.
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