[AstroPy] A question about contour maps

Wolfgang Kerzendorf wkerzendorf@googlemail....
Mon Nov 7 09:26:37 CST 2011


Hi Jean-Baptiste,

So I figure you do not want to plot points at each location of the points specified in your ASCII table? I think APLPy works with pixel coordinates internally and just overplots a wcs grid. You can convert these points with wcstools xy2sky (It also works with pywcs, but for some projections there's something off) to pixel coordinates and then use histogram2d to make a 2d density array. Finally, you use contour to plot it over your aplply plot. I don't know of any easier way for now. May Thomas knows more.

Cheers
    Wolfgang
On 2011-11-07, at 9:58 AM, Jean-Baptiste Marquette wrote:

> Dear AstroPy people,
> 
> I have an ASCII table with RA/DEC coordinates and the values of a given parameter at those positions. I would like to plot a contour map of this parameter on an image with RA/DEC coordinates. I was able create a blank image using pyfits. I guess I could use the APLpy FITSFigure.show_contour method if my data were organized as a FITS file.
> How to export from ASCII to FITS?
> 
> Thanks for your help,
> Jean-Baptiste Marquette
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