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Dear Sir/Madam,I am going to make my observation images with WCS information. I have download reference images with WCS from The STScI Digitized Sky Survey (SDSS) website. However when I open it with IRAF command [b:22eba5a1ce]disp[/b:22eba5a1ce] or directly open it from ds9 window, I cannot see the WCS information. Why? I am confirmed that the images from SDSS are with WCS. But why I cannot see it? Could someone help me for this tiny problem?Thanks for your help!!hymong

For loading images using DS9 directly, ds9 opens the image and reads the header and so will make use of the WCS to display RA/Dec coords. I tried a DSS image and confirmed that this worked, at least with the version of DS9 I have.For IRAF display however, what gets sent to the DS9 as part of the display WCS is the name of the file being displayed and not the actual FITS wcs keywords. DS9 doesn't then use this information to open the image itself the way it would for a standalone image load and so you don't see the WCS readout. This is normal and something that DS9 needs to change to have it work properly.-Mike

Thanks for your kindly and detail explanation on the difference while using loading images with DS9 and IRAF display. But I still don't know why I encountered the problem yet on my system. I have re-installed DS9 to the latest version 5.1. And it seems work well. Sorry to bother you!! And thanks for your prompt reply!!hymong

Will there be or is there already a protocoll which also transfers wcs information from iraf to ds9?
I thought I read something but I can't rememeber
Thanks in advance
Wolfgang

It's not a question of a protocol being available: The current IIS protocol used for display has a 'set wcs' function that includes a full path to the image being displayed, the intent being the server can open this image itself to access pixel and header information (such as XImtool does when sent the image name, or DS9 does when loading an image standalone). DS9 never does anything with this name, but even if every byte of the image were transferred over the display protocol, it is still up to the DS9 developers to do something with that information. The remainder of the 'wcs' sent in a display call consists of a linear mapping of the pixels to the frame buffer and the z1/z2 values to approximate the display value. Access to real pixels and FITS WCS keywords requires the image to be opened.Cheers,
-Mike