[AstroPy] AstroPy Digest, Vol 161, Issue 5

[Mihai Cara]

Because you mentioned "pixel size in arcsec", I assume you are interested in creating images with valid WCS object. In that case, follow instructions in https://docs.astropy.org/en/stable/wcs/index.html#building-a-wcs-structure-programmatically to create a WCS object ("w") and to create a FITS HDU object. The only difference from the example is in the last statement. Instead of

hdu = fits.PrimaryHDU(header=header)

assuming "data" is the numpy array with your data and "slice" is the slice number (0-indexed), you should do:

hdu = fits.PrimaryHDU(data=data[:, :, slice], header=header)

Then write this HDU to a file:

hdu.writeto('slice_name.fits')

Mihai


On 2/13/20, 12:02 PM, "astropy-bounces+mihail.cara=gmail.com at python.org on behalf of astropy-request at python.org" <astropy-bounces+mihail.cara=gmail.com at python.org on behalf of astropy-request at python.org> wrote:

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    Today's Topics:
    
       1. Re: Making fits images with given angular size and pixel
          resolution (Mohammad Shameoni Niaei)
    
    
    ----------------------------------------------------------------------
    
    Message: 1
    Date: Thu, 13 Feb 2020 08:33:48 +0300
    From: Mohammad Shameoni Niaei <m.shemuni at gmail.com>
    To: Astronomical Python mailing list <astropy at python.org>
    Subject: Re: [AstroPy] Making fits images with given angular size and
    	pixel resolution
    Message-ID:
    	<CAAXud8MOvYQgS2CwNKQ9cBZXvbLqHthN_O08H=zzwwx6+v2U4w at mail.gmail.com>
    Content-Type: text/plain; charset="utf-8"
    
    You're looking for "writeto" method. Here a simple script:
    
    from astropy.io import fits as fts
    >
    > dest = "/Output/file"
    >
    > fits_file = "/Input/file"
    >
    > hdu = fts.open(fits_file, "readonly")
    >
    > header = hdu[0].header
    > data = hdu[0].data
    >
    > #
    > #Do something to data
    > #
    >
    > fts.writeto(dest, data, header=header)
    >
    
    On Wed, Feb 12, 2020 at 5:50 PM AISHRILA MAZUMDER <aishri0208 at gmail.com>
    wrote:
    
    > Hello,
    >
    > I have a numpy 3D array of size (200,200,300). The third axis is the
    > redshift (frequency) axis, and the first two axes are coordinates in Mpc.
    > Now I have converted the Mpc values to angular separation using
    > cosmological calculations, and I have determined the pixel size in arcsec.
    > I want to know if its possible to make a fits image out of this 3D array
    > using the pixel size and angular size in Astropy. I could not find any
    > method of doing this hence I am writing this email.  The image (which is a
    > single slice along z axis) should look like image.png attached with this
    > email.
    >
    > Thank you in advance,
    >
    > best regards,
    > Aishrila Mazumder
    >
    > _______________________________________________
    > AstroPy mailing list
    > AstroPy at python.org
    > https://mail.python.org/mailman/listinfo/astropy
    >
    
    
    -- 
    Mohammad SHAMEONI NIAEI
    Astronomer / Software Specialist
    Astrofizik Ara?t?rma ve Uygulama Merkezi (ATASAM),
    Yakutiye, ERZURUM/T?RK?YE
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