The SDSS (Sloan Digital Sky Survey) ImgCutout webservice should return jpeg images for a given field that is defined by the parameters. The service can be tested here: http://skyservice.pha.jhu.edu/DR12/ImgCutout/ImgCutout.asmx?op=GetJpeg

A simple (and working) get query is given here: http://skyservice.pha.jhu.edu/DR12/ImgCutout/getjpeg.aspx?ra=132.749&dec=11.656&scale=0.79224%20%20%20&width=400&height=400&opt=

If you enter the same information (the parameters) in the form of the first link and click on invoke you will get a black image only. You can test the base64 encoded result here: http://www.askapache.com/online-tools/base64-image-converter/

Description of how to reproduce my findings:

  1. Go to http://skyservice.pha.jhu.edu/DR12/ImgCutout/ImgCutout.asmx?op=GetJpeg
  2. Fill parameter 'ra_' with '132.749'
  3. Fill parameter 'dec_' with '11.656'
  4. Fill parameter 'scale_' with '0.79224'
  5. Fill parameter 'width_' with '400'
  6. Fill parameter 'height_' with '400'
  7. Press 'Invoke' button
  8. Convert the content in the <base64Binary> tag from base64 to a jpeg

Following this steps I always get a black image.

Now the question:

Do I require an additional parameter (non empty string) for either imgtype_ or imageField_ in order to not get the correct image? What are this parameters good for anyway?

(Is there a better place this question? It would be nice if there was a tag for SDSS)

  • $\begingroup$ Well the image is not black when I try it .... $\endgroup$
    – Mike W
    Jan 4, 2017 at 14:26
  • $\begingroup$ I tried again and still get a black image. Did you follow the same steps as I now described in more detail (see my recent edit). $\endgroup$ Jan 5, 2017 at 12:54


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